Christian Wolff: Natural right 7 (1747)

In his penultimate book on natural right, Wolff has finally progressed further from the consideration of different varieties of contracts – or at least this seems to be so, since the topic of this book is societies or communities of different sorts. Actually, when the reader begins the first chapter, it is quickly clear that societies are, for Wolff, just another kind of contract (or at least implicit or quasi contract), which is constituted for the sake of achieving some end by combining the forces of those who enter the contract.

The society, Wolff explains, then consists of certain members, which can be individual persons or other societies. Due to the contract they have made (explicitly or implicitly) when entering the society, they are all obligated to do whatever they can to achieve the goal of the society. In addition, the members are also obligated to assist other members in their efforts for the society. Depending on the contract, they may have some further individual obligations. If a member does not fulfill these obligations, Wolff insists, other members have a right to compel them to do so. They should also not allow anyone outside or within society to do anything that would harm the society and prevent it from reaching its goal.

If nothing else is agreed, Wolff thinks, the society will be equal in the sense that all members have the same right and the same obligations, and if certain undertakings of the society must happen in a certain order, there is no order of priority who should do what first. Of course, he adds, the members might have agreed to an unequal society, where some people can have more rights or more obligations than others and where there can be precedence in how things are done. In fact, Wolff suggests, such agreed upon differences in rights and obligations will transmit to people who replace members of an unequal society.

What a society should do for the sake of its goal, in Wolff’s opinion, should be determined by the common consent of its members. Indeed, he suggests, when the society is founded, the members should agree upon the general rules or laws followed by its members: anyone admitted later to the society is then understood to have tacitly promised that they will follow the laws of the society. These laws can later be modified and even cancelled and new laws can also be made. The health of the society depends on members acting in accordance with them, Wolff thinks and suggests that a society has a right to enact penalties for all transgressions of its laws and to offer rewards for people observing them – what these penalties and rewards are, should be decided by the members of the society.

In addition to general laws, society may face individual cases, where a suitable course of action must be decided. Wolff emphasises that in such an event, every member should have a right to declare their opinion on what should be done. This right is fulfilled with voting. If the votes are unanimous, a decision has been clearly made. If not, unless the laws of the society say otherwise and demand a unanimous vote, the majority vote determines the decision. Wolff thinks that to determine the majority vote, one person has a single vote, although he does admit the possibility that votes of those who contribute more to the society deserve more weight.

Wolff considers in great lengths the problem of even votes. A simplest solution, he states, is to leave things as they would have been without the vote (he calls this calculus of Minerva). Of course, this is not always a viable option, so other solutions must be found. Wolff’s next suggestion is to follow the alternative which had least opposition (although he doesn’t explicitly say it, this suggestion appears to demand a use of negative votes). If this brings no solution, in some cases a lot can be used, but if this cannot be done, Wolff suggests using the laws of probability to determine what would be the safest alternative that would most likely do less harm than others. Finally, he notes, the laws of the society may also determine a person who has a right to give the decisive vote in case votes go otherwise even.

Whatever the result of the vote, Wolff explains, it is a legitimate decision, as long as the voting was done according to the laws and customs for voting in the society. Thus, no member has any right to oppose such decisions. Then again, Wolff thinks, dissenting voters cannot be blamed later, if something bad results from the decision made.

Who is then to decide what matters put to vote? Wolff suggests that a right to bring questions to public consultation and to make decisions based on the results of voting should be conferred to some official. If some member of the society wishes to propose some question for public consultation, they should present this wish to the official. If the official refuses to bring the question forward, the proposer has a right to ask the whole society to vote on whether to put the question on public consultation.

Wolff thinks that since individuals cannot achieve all their ends, nature itself obliges us to contract societies: no one is permitted to live a solitary life, to live for oneself alone and not for others. He even speaks of the natural society, which nature institutes without distinction among all humans, the end of which is mutual assistance in perfecting oneself. This natural society is an equal society, Wolff explains, so that all humans have, according to it, the same rights and obligations – indeed, these are the rights and obligations determined by natural right.

A society, Wolff suggests, won’t be licit, if the goal of the society is illicit. This does not mean, he adds, that a society with a licit goal is automatically licit, since it may use illicit means for its goal. One, but not only example of an illicit society is such that is unjust in the sense that its goal is contrary to the rights of someone. An illicit society creates no obligations and it has no members, but is just a collection of criminals and thugs.

Wolff suggests treating societies as persons. This means that just like individual humans, societies have duties toward themselves. Thus, every society is bound to perfect itself and to avoid things that make it less perfect. A society is also obligated to preserve itself and to defend against anyone trying to damage it.

Taking societies as persons leads Wolff to insist that all societies are naturally free, living in a state of nature in regard to one another. Hence, they should be permitted to determine their own actions, as long as they do nothing to contravene the rights of other individuals and societies.

The duties of societies toward themselves impose certain obligations to the members of the societies. Indeed, it is the members who should perfect the society, that is, they should increase the capacities of themselves and their associates to better achieve the end of the society. Of course, the capacities of individuals have their limits. Thus, Wolff explains, although an individual can be part of many societies and contribute to many ends, if their capacities are not enough for this, they are not allowed to enter multiple societies.

A society may be temporary, Wolff explains, if it is meant to exist only for a certain time or if its goal is something that can be achieved only once, or it can be meant to exist for all perpetuity. Even a perpetual society may be destroyed, for example, if the members decide so or if all of them die – or at least so many that it is impossible to achieve the end of the society.

Wolff thinks that a person can leave the society, only if this does not hurt other members – thus, he instructs the leaving person to take care that someone ready to put the same effort into the society takes their place. Then again, there are cases where even this is not required, for instance, when the society is doing something harmful or when the member has lost their powers so much that they cannot contribute to its affairs. Wolff also notes that the society can also remove some members from the society, for example, if they refuse to provide to the society what they are obligated to provide or if they refuse to listen to the opinions of other members about common affairs.

According to Wolff, society rules its members concerning actions that further the end of the society, and indeed, he thinks, the concept of ruling has no meaning outside societies. Wolff notes that a society can retain the power to rule its members within itself or it can transfer this power to an individual or individuals (even to such that are not members of the society). The conditions of this transfer – e.g. if the transfer is temporary or for life, if all power is transferred or only some part of it etc. – is to be decided by the society. Indeed, Wolff explains, they determine the fundamental laws of the society (in case of states, we would probably call it a constitution). If the ruler then demands something against these fundamental laws from the members of the society, they need not obey this.

Before moving on to discuss particular societies, Wolff makes the remark that societies can have obligations toward individual human beings and toward other societies and they can also receive rights from either. Thus, societies can enter into contracts, and if they do, they are obligated to honour these contracts and can be blamed, if they do not do so.

Crusius, Christian August: Road to certainty and reliability – Interpretation

The final chapter of the logic of Crusius deals with interpretation or the search for the correct sense of some signs of thought – usually words in a text – that is, the attempt to determine what thoughts these signs or words express. He notes that this sense has two meanings. Firstly, the grammatical sense of words means for Crucius the sum of the meanings these words can have in a language. He notes that words can have many primary meanings, that is, they can refer to various objects, and furthermore, they can also have secondary meanings which express not what the words primarily refer to, but certain attitudes of our mind in regard to designated topics.

The second meaning, Crusius adds, is the logical sense of the words, which tells us what these words mean at a certain place and in a certain context, and notes that to get to this logical meaning, we first have to check the primary and secondary grammatical meanings of the words. In addition to grammatical and logical sense, Crusius speaks also of a mediate sense of the words, which includes correct consequences of the primary meanings, but only under the condition that the speaker has intended to imply these consequences. Furthermore, he mentions a symbolic sense of words, where certain topics are used for the purpose of designating and prefiguring other topics.

Crusius divides interpretation of text in two kinds, the first of which is grammatical interpretation, where obscure words are made distinct through other words that more easily convey some concrete ideas – he points out that translation can be regarded as grammatical interpretation from one language to another. The second kind Crusius then calls, quite expectedly, a logical interpretation, where the meaning of the words is determined through justifications found in the text itself or elsewhere.

Crusius further divides logical interpretation into common and scholarly forms. By common logical interpretation he means interpretation that uses only a natural sensation of true and false perceived in a concrete idea without knowing the idea distinctly. Then again, in scholarly logical interpretation the justifications of the interpretation are known distinctly. Crusius adds two degrees of perfection to scholarly logical interpretation: we can either know the justifications distinctly according to their content, or we may be capable of justifying them according to their form and ability to prove things from them with the rules of logic.

Crusius takes as his starting point the fact we usually understand a lot, if not most of the texts we read without interpretation, if texts are just written straightforwardly and not ambiguously. Interpretation, he then adds, is required only for obscure passages. Then again, Crusius notes that we should observe why many passages in a text are distinct without interpretation and analyse concrete ideas about them. Such distinct passages, he thinks, form a secure ground for interpreting the whole text.

Crusius counts three essential grounds, on which to base the interpretation of the words of a text or a speech. Firstly, he says, we should observe the author and their characteristics: for instance, what capacities they have, in what context they have lived, what is the time and the occasion where they have spoken or written and what kind of sciences, religion, habits and customs they have had. Secondly, Crusius continues, we should observe the means the author has used or the characteristics of the language, in which they have written or spoken, both of the particular languages used and of the human language in general. Finally, he concludes, we should determine the purpose of the speaker, both in whole speeches and texts and in their individual passages. In addition to these essential grounds, Crusius points out, we should also observe contingent means of expression, such as the tones, gestures and hand movements. Besides all of these, he finishes the discussion, we should most importantly consider the text or speech itself and compare its words and passages to one another, in order to find out any harmonies within it.

Interpretation is no demonstration, Crusius notices, but uses the method of probability, because words are arbitrary signs and internal conditions of humans can be known only through probabilities. Interpretation can be hypothetically demonstrative, he admits, if we assume that presupposed circumstances and statements of the author should not contradict one another. Furthermore, Crusius remarks, interpretation can have moral certainty that is effectively as good as demonstration, and just as we know from his study of probabilities, moral certainty can be generated from mere cognitive reasons, but also from additional grounds given by obligations. Still, he concludes, all interpretations must be justified logically as sharply as possible, that is, we must prove that the interpretation has at least objective probability or otherwise it is doubtful or false.

Where to then start the search for the sense of the text? Crusius notes that we should firstly reject any opinions that would make all interpretation uncertain and doubtful, because otherwise the whole notion of interpreting would become impossible and language would be useless: besides it would be against our own purposes – we ourselves want to use language – and against the divine wish to reveal themselves to humanity through linguistic means. If this preliminary has been fulfilled, Crusius continues, we should determine what is familiar and proceed from that to what is unfamiliar. Furthermore, he adds, because we must understand the words from the standpoint of the author, we should try to find out their circumstances and place ourselves into their perspective. In addition, Crusius notes, since we have a natural disposition and capacity for imitation, we should consider good examples of correct and well-made interpretations.

Crusius outlines four most general presumptions of probability in interpretation. Firstly, as long as we have no reason to suppose that a person is a fool, rash or incapable and their words can be interpreted in a reasonable fashion, or at least they cannot be proven to be indecipherable, we should not presume them to contradict themselves. Secondly, we should presume everyone to speak distinctly and with understanding and to avoid obscurity and ambiguity – still, this does not mean that they would also determine their words carefully. Thirdly, we should presume that the author says what their purpose demands, and finally, we should presume that everyone speaks and writes according to their state of mind (for instance, that their emotions can be seen in what they say and write).

Crusius proceeds to some particular rules for determining the meaning of the words. Firstly, he notes, we should not dismiss at start what has been proven to be their character, but we should accept what indubitably follows from this character. Then again, what does not conflict with this character should not be taken as a problem to be solved, although it isn’t a necessary consequence of this character. Furthermore, we should try to experience as much as possible about the external and the internal circumstances of the author to get a correct idea of their character and to find the right perspective, from which they consider things, although we need not know all the details of their life. Finally, because unfamiliar is to be explained from familiar, we should read the text to be interpreted a couple times through.

Considering the language of a text, Crusius notes that if the text is not a riddle, its words should be presumed to have a unified meaning, although this meaning can be a whole consisting of many grammatical meanings: especially if there have been more authors than one, he points out, the words could have multiple meanings. Furthermore, if we just know the language used well, Crusius continues, we should find out all the grammatical possibilities of interpreting words – that is, possible definitions of words that do not go against the nature of the language used – and all the exegetical possibilities – that is, possible definitions that in addition to grammatical ground do not contradict any other grounds of interpretation. If then we have a string of words, the combination of which is both a grammatical and exegetical possibility, we should primarily assume that the words form a unified meaning, although Crusius admits that is not always the only or even the best interpretation. Then again, he adds, if some peculiar phrase seems just a weirdness of the language used, we should assume that it is so.

Crusius instructs the reader to follow primarily the most usual sense of the words, unless there are some weighty reasons to do otherwise: if we do decide to follow another interpretation, we should show that the other reading is possible and prove that it is better in this particular case. If the author has used signs of opposition, he continues, we must suggest their words to have such a sense that recreates this opposition. In general, Crusius adds, we should presume that different words refer to different concepts, unless there are weighty reasons to do otherwise. He admits that this last principle has many exceptions. A person speaking with emotion often repeats the same issue in different words, because they can only think of this one thing. Furthermore, if a person wants to gain the attention of the listener or the reader, they often state something obscurely and then say the same thing in clearer terms. In addition, a person wanting to say something with unrestricted generality often uses many equivalent expressions for the same thing, because they want to drown their opponents with their words. Finally, Crusius concludes, if an author is a genius with words, they often show their skill by inventing new expressions for the same things.

Crusius suggests that we should not assume that a word in a text is used with all its possible meanings, although we should also not ignore any meaning that makes sense in the context of the text. If a sentence of an author should be determined by another sentence of theirs, he continues, we should choose a sentence naturally fit for this task. Furthermore, if the subject of a sentence is in doubt, we should assume that it is the one that is in itself a subject.

Crusius goes through some means for finding affections, and in general, the state of mind of the speaker. Firstly, he says, we should study the general theory of will and its changes, together with their natural and arbitrary signs. Secondly, we should find as much information about the individual circumstances of the speaker as possible, and finally, we should observe all circumstances about the nature of the topic, whether they are present in the text or elsewhere. Similarly, Crusius adds, is to be evaluated the emphasis of the words in a text, where by emphasis he means an expression of a certain intensity of the movements of the mind, caused by the perceived magnitude and importance of the issues.

Crusius mentions three ways how we can determine the purpose of the author, the easiest being if they say it themselves and we should just observe it. The second possibility is that we determine the purpose from the nature of the topic, insofar as we can assume the author to be a reasonable person. Finally, we might be able to determine the purpose from the consideration of the text as a hypothesis and then confirm it by comparing it with the circumstances of the text (text should be the means for the assumed purpose). The final method, Crusius notes, is the most usual one, but he adds that the circumstances need not cohere with the suggested purpose necessarily, but their coherence can also be only probable or possible, because although the circumstances do not prove the truth of the purpose, they at least can help to clear out some difficulties. In the latter case, he adds, the knowledge of the possibility of coherence is either determined and perfect, if we see distinctly why and how circumstances can agree with the presupposed purpose, or undetermined, if we just see no conflict between the circumstances and the assumed purpose.

Considering contingent means for expressing thoughts, like tones and gestures, Crusius notes that we should observe whether what we assume to be a sign actually is a sign or whether it is common to many things and whether it is a certain, probable or merely possible sign. If, he adds, we do not ourselves immediately observe these signs or have historical documents telling us about them, but we just assume them for the sake of completeness or as subsidiary hypotheses, they must be particularly proven or they must be confirmed through the proof of the main hypothesis or we should not assume them to be true, but add them merely as possible determinations for the sake of distinctness or for justification of reasonableness of the text against objections and accusations.

When considering the text itself, Crusius notes, we should observe partly the connection of a passage to what precedes and what follows it, partly the parallel passages. Considering the preceding and the following, he thinks, is our main source of interpretation, because it is not just the nearest and the easiest means, but its use is also required by all other methods, because through it we avoid the danger of putting our own opinions to the mouth of the author. As further rules Crusius suggests that if we compare the preceding and the following to explain a text correctly, we should not assume ambiguous phenomena to prove anything, we should not fabricate connections from careless subordination of a part of the text to the abstracted purpose, and we should not assume a connection with a more distant idea, when we have a nearer idea to connect it with.

By parallel passages Crusius means passages that have something similar in them, whether similar linguistic expressions used or discussion of similar things. He notes that parallel passages are of great use in interpretation, because they help to determine the more obscure passages from the author’s own explanation – it is difficult to err, if the author explains something in many places. Crusius notes that parallel passages can be used positively, to determine the sense of words, or negatively, to determine what is not meant. Sometimes they can be used to prove the possibility, sometimes probability and sometimes certainty of interpretation.

The main rule of Crusius for parallel passages is, again, to explain more obscure from more distinct. He adds the more detailed rule that parallel passages of verbal expression can in themselves prove only the real possibility of a definition, but in deciding between several meanings, parallel passages can decide which is most probable. If we have two parallel passages, Crusius notes, one of which describes more circumstances and more determinations, we should not take them as equivalent, just because of their parallelism. If the parallel passages are from the same author, they prove usually more than if they were from different writers, but if we use a parallel passage from another writer, we must be able to presume a sufficient similarity between them, since otherwise the parallel passages can prove only logical possibilities. Generally, Crusius insists, the closer a justification for interpretation is found, the more reliable it is.

When we are trying to determining the grammatical meaning of words, Crusius tells the reader, we can rely on the common use of language, on etymology and on such words or languages that have affinity with the given. The first method to be tried, he thinks, should always be the common use of language. We should first search for the meaning and the application of the words, where it can be known with moral certainty, from such people who know the language. With the help of these familiar words, we should then determine the more doubtful and obscure words from the context. Crusius underlines that the certainty of the interpretation does not lie with the masters of language or dictionaries, which also contradict one another. Instead, such sources must be compared with one another and we must see how words are used in different contexts, following the rules of probability.

If we are forced to use etymological means, Crusius continues, we must check how reliable these etymologies are. Even if they are reliable, he notes, this proves only that the interpretation is possible and the proof relies on an analogy with other words, the meaning of which can be assumed from the use of language. Etymology can prove probabilities only in cases where counter examples are rare, and usually a real possibility is proven only through many examples. Finally, affinity of certain words or languages can only prove such a possibility of meaning under the condition that the earlier means are not available and the context also suggests the assumed possible meaning.

To determine the logical meaning of the words in certain context, Crusius notes, we should first note that a grammatical ambiguity does not necessarily make the words obscure and ambiguous in this context, because experience shows that we can use ambiguous words and make ourselves understood. Means for finding the sense of the words in a context are, he counts, opposition of concepts (what a concept is opposed to or at least what it is distinguished from), subordination of concepts or ascribing predicates and relation to it, parallel passages and special additional means. Crusius also suggests two possible methods for deciding the meaning in the context. Firstly, we can infer the meaning from the just mentioned oppositions and connections, or secondly, we can assume a possible interpretation and see if it fits with the text. Latter method is to be used, Crusius thinks, if there are not many predicates and opposites to be found in the text and the word is used by the writer only a few times – if it concerns matter of common life and the meaning of a word can be assumed to be certain and it makes sense in a context, the explanation is morally certain

Searching for the sense and connection of propositions, Crusius thinks, we should observe what can be assumed as more familiar: subject or predicate, conclusion or premisses, parts or whole propositions. If every explanation of a text leaves some prominent difficulties, he notes, we must take care that they don’t have just subjective probability. All in all, Crusius thinks, probabilities of interpretation are easily very high, since there are often harmonies to be found and the meaning of many words has moral certainty. Thus, he says, it would be absurd to assume that we wouldn’t understand an ordinary letter from a friend, and even more obscure documents contain some distinct elements.

Crusius, Christian August: Road to certainty and reliability – Historical probability

From the general method of all research, Crusius moves on to the specific method of history. He thinks it evident that proofs in history can only use the method of probability: the links between the things in the world are so multifarious that we cannot discover the events from causes or causes from events through demonstration, and even where we could find the causes of some effects according to their essence, we could not find all circumstances of their existence. Furthermore, Crusius adds, the events of history are usually determined by the choices of free persons, while the method of demonstration can investigate only deterministic causes. Thus, he finds enough reasons to define a special historical probability, by which he means probability that helps us to distinguish justified accounts of the past from fabrications. Crusius believes that in innumerable examples of human life we have occasions of historical probability and that it often even changes into moral certainty. This means, he concludes, that we should be able to find ways to justify historical probability.

Crusius suggests several ultimate grounds of historical probability, starting with the assumption that especially fabrications, untruths and affectations reveal themselves quite easily, since it is not easy to create internally consistent stories, because fictional tales often clearly conflict with the known events of the real world and because our natural desire for truth makes it not easy for us to be fooled by deceptions. Indeed, he suggests that because of this natural desire for truth, people find credulity and deception shameful things and are therefore usually inclined to tell only such stories that they have judged to be true due to believable justifications. Thus, Crusius concludes, we should not presume that a historical account is groundless, as long as we know no particular causes that would weaken or even expressly refute the general presumption.

Of course, Crusius adds, this presumption has different degrees, depending on who is giving the account, and is especially strong in regard to public records. He notes that each person usually acts according to their status, for instance, a person who has been deceitful before is not to be trusted. Furthermore, Crusius continues, the easier it is to believe something to be possible or the more internal probability something has, the stronger is its trustworthiness. Here the particular method of historical probability points back to the general theory of probabilities: probability increases greatly, the more we have justifications and the more harmonious they are with one another. Even mere cognitive justifications might be enough for moral certainty, but links to purposes and obligations increases its strength, but no method of probability can be used further than its own justification allows, that is, when it is not weakened or even expressly refuted by opposed inferences.

Crusius notes that there are two things to evaluate with the historical justifications: firstly, the materials used as data for historical proofs, and secondly, their relation toward the suggested historical truth, the signs and grounds of which they should be. He points out that historical data can be of many types: not just history books and records, testimonies and accounts, but also memorials, coins, pictures, inscriptions, artifacts and even internal characteristics of the suggested events, that is, whether they are in themselves probable. Crusius states that first is to be investigated how certain the data are, sometimes through immediate sensations, sometimes through demonstrative grounds, but mostly through other probabilities.

Crusius reminds the reader that although we would have answered the question of the certainty of the data, we still wouldn’t have decided what the data can prove. This power of proof lies partly, he continues, in the existence and characteristic of testimonials of witnesses and in the characteristic of the things witnesses have told. Starting from the latter, Crusius explains that we should observe the possibility and the probability of things even before looking at the testimonials. Thus, he argues, we should consider the degree of possibility of the described event: for instance, are there many examples of similar things and are there clear causes that could have caused the thing at the context of that time. Furthermore, Crusius thinks, we should observe whether the suggested event has internal probability: whether it agrees with known physical and cultural circumstances or whether it contradicts them, whether the existence of such things is probable from general reasons etc. He also encourages to find any physical evidence corroborating what is told.

In addition to such internal characteristics of events, Crusius recognises testimonials as the other main source of historical proofs, whether they be testimonials of the experiences of the witnesses themselves or of someone else. He notes that we should observe whether the witness could have given a true testimonial. If they are speaking of something they have themselves supposedly experienced, do they have the required powers of sensation and attention, how much they could have actually sensed, what kind of obstacles their sensations might have had and how much time and attention the thing has required? On the other hand, Crusius adds, if we are speaking of something not directly experienced, but only inferred from something supposedly experienced by the witness (e.g. whether someone was angry), we must observe whether the witness has enough power of reasoning to do such inferences. Finally, he concludes, if the witness hasn’t personally encountered the thing they tell, the probability of their testimonials depends on the methods they have used to ascertin the truth of these tales and their capacities to use these methods.

Furthermore, Crusius continues, we should observe whether witnesses have wanted to tell the truth, that is, we should observe if for some reason it is easy to assume that they do not speak truth or whether some particular circumstances of the witnesses, such as their character, prevent this assumption. He also suggests considering whether witnesses could have deceived us, and if so, whether the deceptions have been done purposefully or due to witnesses themselves being deceived by others.

An important topic of investigation, according to Crusius, is whether testimonials agree with other testimonials – for instance, whether what the witness says here agrees with what they say elsewhere and with what other writers and historical records suggest. Even if a testimonial appears to be in contradiction with other testimonials, this seeming contradiction might be solved in other ways. If a testimonial cannot, for some reason, be compared with others, the events might still be remarkably probable for other reasons.

Crucius suggests some further rules to help in assessing historical probability of an account. Firstly, he notes, events that happen seldom or are in conflict with the natural characteristics of the causes in the world are internally improbable, thus, they require stronger historical justifications in order to become credible. Furthermore, Crusius points out, all justifications of historical probability can confirm each other reciprocally, that is, earlier events can confirm their consequences and consequences can confirm past events that caused them – we just have to know which of the two are more reliable and use them to justify the others. He also suggests that at least when dealing with events that could have been experiences, memorials of famous people provide stronger evidence for them than memorials of unknown people, while physical evidence, like coins, are generally more credible evidence than memorials.

Every testimonial has, Crusius reminds us, historical credibility, due to the presumption that people mostly speak truth, but this natural credibility can be weakened or even completely refuted by the circumstances or it can also be strengthened. Thus, historians should try to have as much information about the historical context, in order to better evaluate individual testimonies. Usually, Crusius notes, having several witnesses saying the same thing makes the account more credible, but if all the witnesses have heard the tale from the same source, their combined credibility is as great as the credibility of this source – unless, he adds, the witnesses have had more evidence, on which to base their belief in the original source. In any case, Crusius concludes, the character of the witnesses can weigh even more than their numbers.

Sometimes the credibility of testimonials is low, Crusius thinks. If a witness has not immediately experienced something, but merely makes a judgement that things have happened so and we cannot say what their judgement is based on, their testimony is as good as nothing. Also, if it seems quite possible that a witness could have erred or is speaking partially, they are to be deemed unreliable. Then again, Crusius states, if the witness gives an unforced account of a remarkably long, but still coherent series of events, this suggests that the tale is credible. Further indications of credibility, he suggests, are modest acknowledgements the witness makes of their own ignorance and sudden revelations of things the witness should have been quiet about (although the latter can also be, Crucius admits, a sign of a naive or a rash person).

Crusius warns that we should not confuse credibility of a single event and credibility of a historian in general. The latter can give credence to the former, but it is not the only possible justification for an event; besides, before becoming a credible historian, a person has usually established credibility of many historical events. Crusius also reminds the reader that they should distinguish between immediate and mediate witnesses. Immediate witnesses have themselves experienced something and then the question is, whether their experience has been complete enough and whether they have reported it faithfully. A mediate witness, on the other hand, has relied on the accounts of others, public records and other sources, and then the question is more about the credibility of these primary sources and about the ability of the mediate witness to use them without making things up on their own. Usually, Crusius thinks, immediate witnesses are to be preferred over mediate witnesses, although sometimes the immediate witnesses might not have had the opportunity to observe the event from all angles (for instance, a single soldier might understand less about the ongoings of a war than a researcher who has studied its course for a long time). Similarly, he points out, historians living closer to the time of an event are usually more reliable than later historians, but geographical distance, lack of understanding of the context (e.g. when a person of an upper class writes of the ongoings of the lower class) or partiality can weigh the balance on the side of the later historian.

Crusius thinks that historians relying on proofs lose their credibility, if we observe them using unwarranted sources or contradicting themselves. Then again, he states, mere unfortunate speculations about reasons of events do not destroy their credibility, if they just clearly distinguish these speculations from established historical events. If we are reading a work of an unreliable historian, Crusius continues, we should believe only such things, which seem in itself possible or probable or which are confirmed by other witnesses or justifications. He is also of the opinion that a single unfounded treatise should not make us suspect the historian in general, just like a single error should not make us suspect the whole treatise.

Crusius warns not to take a lack of mention of an event by historians as evidence of the event not happening. If we want to do so, he explains, we should show that there are no understandable reasons for their silence, such as a fear of state officials or religious beliefs, or we should show that being silent on a major event would contradict the character of the writers. Then again, much stronger evidence against the truth of some event than mere absence of mention, Crusius thinks, is provided by an account of a historian explicitly contradicting the supposed historical event.

This leads us to the question what to do, when historians give conflicting accounts. Crusius suggests that in these cases we must observe the individual circumstances of the writers: for instance, whether they count the time differently or whether they speak only of similar events. Sometimes nothing more is needed than clearer definitions of words, he assures the reader. Whatever we suggest for explaining the seeming conflict, Crusius underlines, we have to consider whether we want to show that the suggestion is true – then we need to prove it – or whether we just try to justify the credibility of the historians – then it is enough that our suggestion is a real possibility. Crusius concludes by insisting that a conflict of historians requiring explanation does not necessarily weaken the credibility of their accounts and a good explanation might even strengthen their credibility.

Crusius concludes the chapter with the question whether the length of time that has passed from the event takes away from its credibility. His answer is essentially negative: the existence of triumvirate in Rome is as believable now as it was during the age of Charlemagne. True, he admits, we might have less justifications to believe an event to be true, especially if we find new evidence to refute earlier accounts. Then again, the credibility might, on the contrary, also increase through new evidence, he notes, so that what was earlier just a widely spread rumor, might in the new circumstances become credible history.

Crusius, Christian August: Road to certainty and reliability – Research and teaching

Like the logic textbooks of the time often did, the final few chapters of the work of Crusius treat the question how to apply everything previously said to the practices of scholarly work. Crusius speaks more precisely of meditation, by which he means a process of extending our knowledge further from some fundamental thoughts. In addition, he considers also the related problematic of how to transmit the internal meditation to others in a scholarly treatise, which requires accommodating the results of meditation to their needs. Crusius also ponders the practices of disputation, but has not that much new and interesting to say about the topic, so we’ll ignore it.

Quite traditionally, Crusius distinguishes two different types of meditation: analysis, where we try to make our knowledge of the fundamental thoughts more distinct, complete and certain, and synthesis, where we progress from fundamental thoughts to other truths that are not its part nor grounds, but are merely inferred from it. He notes that both actual meditation and scholarly treatises use both methods and that sometimes even individual pages in treatises can have many occasions of both methods.

In the synthetical method, Crusius thinks, the fundamental thoughts studied must always be concepts, but the analytical method can also have as its object words, the meaning of which is sought out. Thus, he argues, the analytical method is divided into analysis of things or concepts and analysis of words or terms. Starting with the analysis of concepts, Crusius divides it again into analysis of parts, which sets out distinctly all the parts and internal determinations of the fundamental thoughts, and analysis of reasons, which looks for proofs for the fundamental thoughts and evaluates proofs suggested by others. The difference of the latter from the synthetical method, he explains, is that we are usually convinced of the proof of the fundamental thoughts and we just want to make this conviction more secure.

Crusius divides the analysis of parts again into merely resolving analysis, which sets apart distinctly just what is already in the fundamental thought, and determining analysis, which adds further determinations to what is still indeterminate in the fundamental thought. He calls the latter also mixed analysis, because it often has to use also the synthetical method, although for an analytical purpose. This determining or mixed analysis, Crusius explains, adds either determinations that belong to the object all the time and thus are part of its essence or determinations that belong to the object disjunctively through divisions.

Crusius notes that the methods of analysis of parts and analysis of reasons can also be combined. This combined method is especially used, he explains, with problems, where we start from given data and progress to the grounds, on which the data depends, and generate from the characteristic or quantity of the grounds the required characteristic or quantity. In this method, Crucius points out, the first move toward grounds is analysis of reasons, while using the grounds to make the previously unknown determination distinct is determining analysis. He points out that this method is especially used in mathematics, under the name of algebraic method, when we are asked for a magnitude of something and we determine it through other magnitudes, on which the first one depends.

Analysis of words or texts Crusius divides into three types. Firstly, it may be about interpreting a text, it may be about outlining the order or disposition of the text or it may be about evaluating the worth of the text. The interpretation is something Crusius will return to in the final chapter of the book, so he in this point merely divides disposition of text into natural disposition, which follows the goal of the author, and artificial disposition, which follows any convenient general concept, and divides evaluation of the text into evaluation of the writing style and into evaluation of the thoughts in it.

Crusius lists three kinds of synthetical method, which he names after the sciences prominently using them. First of them is the geometric or mathematical method, which takes as its starting point the concept of a possible essence. The second, then, is the physical or experimental method, which starts from propositions involving physical existence. The final one is the moral method, which begins with propositions involving moral existence. Crusius notes that the physical and the moral method together can be called the philosophical method.

Crusius goes through the different types of synthetical method in more detail, starting with the mathematical or geometrical method, where the possible essence it begins with is such that the existence of which is not yet posited or at least not yet considered. This method then proceeds to find out more about the relations and consequences of the essence and discusses problems following from these. Crusius notes that the specialty of the geometrical method is that it does not prove its definitions, but just postulates them as possible. Thus, he argues, propositions shown by it have only a hypothetical reality, which is enough for pure mathematics. Then again, Crusius points out, the geometrical method is used elsewhere, for instance, in studying the relations of possible essences.

The physical method, Crusius continues, starts from experiences or real propositions deduced from experiences – he notes that all existences must in the end be justified from experiences. The method then proceeds to other propositions involving physical existence or real possibilities. In other words, Crusius explains, the physical method moves from effects and properties of things, known by experience, to their causes, further effects and relations. The method is used, naturally, in physics and also in medicine, which Crusius takes to be a special subspecies of physics. He notes that this method is used also elsewhere, for instance, in revealed theology, where the Bible takes the place of experiences.

Moral method, finally, proceeds from fundamental thoughts to the purposes of things or from posited purposes to other purposes, whether these purposes concern human happiness or moral laws. In case of moral laws, Crusius thinks that we know them sometimes through sensation – when we are speaking of written or announced laws – and if we are speaking of natural laws, we can know them by deducing from experience, although he warns the reader not to confuse inferences from what makes us happy for a proof of moral law. Crusius also points out that studies of moral existence or possibility should not be confused with studies of efficient causes and means that make certain conditions of mind possible or actual, because the latter demand the physical method. Then again, he adds, most moral topics also require these physical investigations.

Crusius states that the synthetical method cannot be applied before the fundamental thoughts are distinct and known to be real or at least possible, which presupposes that we know definitions, experiences and other propositions. Definitions in particular, he says, should at least be resolved into axioms, and if this is not enough, determining analysis is required. Thus, Crusius argues, both analysis and synthesis are required in meditation, but synthesis presupposes analysis. Furthermore, he continues, each thing must be studied according to its nature. For instance, existence must be studied analytically and especially through determining analysis or synthetically with physical or moral method or often by both means, while study of essence requires mathematical method or analysis.

Crusius also gives some general guidelines on how to go about in meditation of things. A central concept here is the theme of meditation, by which he means its main or objective purpose. The theme is either simple – a concept, a proposition or a problem – or composed of many simple themes. If the theme is something arbitrarily made by humans, Crusius says, we should check whether it is useful to investigate it. With naturally generated things this check is not required, he thinks, because knowledge of such things enriches the sciences and influences many truths.

In order that meditation will be useful, Crusius explains, we should already have some capacities for meditation, which requires a diligent and thorough study of logic. In addition, he notes, meditation requires materials, which are supplied by preliminary knowledge that helps to form concrete ideas, both on the general structure of all sciences and particularly on sciences close to the theme investigated. Crusius also instructs the reader to learn about history, because historical knowledge can provide experiences and understanding on causes of many possibilities.

After gathering this preliminary knowledge, Crusius explains, the meditation starts by directing attention to the fundamental thoughts and trying to think them lively and ever more perfectly. This means, he adds, reflecting on and analysing examples that fit the concrete ideas, together with the opposites of these examples and the predicates that are ascribed to the examples through the concrete ideas. In addition, we should recollect what we have heard and read about the topic and perhaps collect more experiences about it. When all of this is done, Crusius suggests, we should draw an outline of the meditation to guide our imagination, by determining the main points in the theme, to which meditation should be directed.

Once we have fixed the purpose of meditation, Crusius insists, we should make a special theme about the requirements of the method. This means, firstly, he explains, planning a good order for the meditation or the treatise made through it. The general rule, Crusius says, is to start with that without which the following cannot be understood, at least not as conveniently. This does not mean, he clarifies, that nature would determine the place for each thought so precisely that they could not change their places, because there’s much arbitrary in the order of meditation and scholarly treatises.

Something peculiar to treatises, in opposition to meditation, Crusius suggests, is that although in meditation scholars should be ready to reduce everything to first grounds of all sciences, it would be too difficult to do that for every proposition and often superfluous in the eyes of the reader. Still, he adds, we should not assume as familiar what is doubtful and we should try to find justifications even for familiar truths, especially if this is a key to finding desired truths, or to shying away from difficulties.

Crusius suggests that the working of themes is easier, when their main points are classified and ordered under a few titles – he calls this classification by the Aristotelian term topics. I shall skip this part of the chapter, because it consists mostly of titles of the treatise to be made.

Crusius, Christian August: Road to certainty and reliability – Proving

After propositions, Crusius naturally progresses in his applied logic to proving, where a proposition (the conclusion) is held to be true because of its relation to other propositions assumed to be true (the premisses). This relation, he explains, is formed by a chain of deductions, and while the premisses could be called the matter of the proof, the deductive chains are similarly its form. Crusius points out that there is a clear hierarchy what can be proven from different kinds of propositions: thus, a nominal proposition about mere words cannot be used to derive ideal conclusions about possibilities, let alone real conclusions about the existence of things, while ideal propositions cannot be used to back up real conclusions. He also notes that proofs can have different purposes: sometimes we just want to see what follows from assuming some premisses as true – this could be called a hypothetical proof – while at other times we truly want to establish the truth of the conclusion – this is then an absolute proof.

Crusius goes through several ways to classify proofs, starting with whether the proofs use only the proposition of contradiction or whether they rely also on the two other fundamental propositions. Furthermore, he adds, proofs can be divided according to whether the method used is the demonstration or the method of probability. The first kind – demonstrative proofs – can then be combined with the classification of the first sentence, so that we gain the concepts of geometrical demonstration, which uses only the highest fundamental proposition, and disciplinary demonstration, which takes advantage also of the two other fundamental propositions.

Crusius also divides proofs in a priori, a posteriori and mixed proofs. Of these, he explains, a priori proof establishes not just that the conclusion is true, but also why it is true. A priori proof can also be what Crusius calls a hypothetical a priori proof, which tries to develop a conclusion implicitly contained in some premisses, or an absolute a priori proof, where the conclusion is intrinsically connected, but not implicitly connected with the premisses. The names of these subtypes is explained by hypothetical a priori proof being also hypothetical in the sense of merely explicating the premisses, while the absolute proof should establish truths through the mere fundamental propositions and axioms immediately dependent on them, such as those involving causal powers of things.

A posteriori proof, then, means for Crusius a proof which establishes only the truth of the conclusion without explaining it. As is to be expected, he includes all proofs dependent on experience in this class, but somewhat surprisingly also the so-called proofs ad absurdum, where a conclusion is derived by showing that the supposition of its falsity leads to absurd conclusions (of course, the latter do not explain why something is the case).

Crusius includes also a third kind of or mixed proof, which should be in some sense a priori and in another a posteriori. His paradigmatic example of such a proof is those found in geometry, where objects according to some defined concepts are postulated to exist and then the existence or characteristic of some objects is established. Such proofs are first and foremost a posteriori, since they do not really explain the conclusion – that’s why Crusius calls them mixed a posteriori proofs – but the method is still a priori in the sense that the justifying ground of the proof is comprehended from the mere idea of the proposition to be proved.

All proofs should prove the truth of their conclusions, Crusius says, but not all of them establish the necessity of the conclusion. A priori proofs, he states, always do this, but the degree of necessity depends on the necessity of their grounds: thus, Crusius notes, if we want to prove the existence of something absolutely necessary, it must be proven a priori from the properties of God. When it comes to other kinds of proof, he states, deductions ad absurdum and mixed proofs prove the necessity of their conclusions, while proofs from experiences prove only the truth of their conclusions.

Observing the purpose of proofs, Crusius notes that they either prove something from the standpoint of truth and try to establish some conclusion as true, or then they prove from the standpoint of humans, that is, indicate what a person must admit, if they accept something as true. Another point of division concerns the question whether the proof uses only the tools of understanding or whether it aims to justify some course of action and is thus dependent also on moral issues.

With these divisions out of the way. Crusius goes on to explicate some rules on how proving is to be effected. Thus, he says, we should begin with the preliminaries of making all the concepts distinct and analysing the required conclusion. If we want to prove the existence of something, Crusius underlines, we have to base the proof ultimately on experience, which is our only criterion of existence. This does not mean that we can use only a posteriori proofs for this, since we can also use an a priori proof to justify the existence of something from the existence of something else, for instance, through causal connections.

Proofs are based on premisses, but should the premisses then in turn be justified? Crusius notes that all true scholars are committed to linking all conclusions that we want to proof with the highest grounds of all thinking. Yet, he admits, in individual scholarly treatises such long chains of proof are cumbersome and we should, in case of proofs aimed for convincing certain persons, not go further than what our opponents consider acceptable, and in case of proofs aimed for establishing some truth, not go further than to certain postulates that require no further proof and to lemmas from other sciences.

With such basic rules established, Crusius moves on to discuss fallacies, which he quickly admits is a topic, the various types of which need not be learned – and although he then proceeds to list various types of fallacies, this listing shows almost nothing of interest, so we can skip it over. What is more interesting is the notion of colliding or conflicting proofs, which Crusius has inherited from Hoffman and which bears striking resemblance with the so-called antinomies of Kant. In effect, Crusius defines colliding proofs as a case where we have various proofs that seem trustworthy by their form and matter and have the necessary signs for truth, but these proofs also lead to conclusions that cannot all be true at the same time. The colliding proofs are not fallacies as such, because proofs with similar properties are reliable in some contexts, but not just in this particular case.

The first question is, Crusius notes, how colliding proofs are possible: how can a proof have all the signs of being true, without being so always? One problem here is, Crusius explains, that something cannot be both true and false at the same time. His answer is to distinguish objective from subjective truth: objectively considered, nothing can be both true and false at the same time, but what is objectively false can still be subjectively true, that is, have signs of truth, but only in a restricted sense. Another problem is that colliding proofs seem to refute our capacity to know what is true, if we cannot rely on signs of truth. Crusius points out that these signs of truth do work, but with restrictions.

What then are the particular reasons for the appearance of colliding proofs? One special reason Crusius picks out are the latter two of his fundamental principles and all propositions based on them, which are reliable within their limits, but lack the completely universal validity of the law of contradiction. Thus, he explains in more detail, although these principles hold of finite things, they might have exceptions with infinite, which is not just different from finite things by some quantitative degree, but by its essence. Furthermore, Crusius adds, even if these principles hold of things in the known parts of the world, we do not know whether things are different in other parts of this world or at least in another possible world. Crusius concludes by assuring the reader that God must have had a good reason for making these principles work only within these restrictions, and any errors are just an unavoidable side effect. Besides, he adds, the collisions are a clear criterion, by which we know we have overreached the limits of our knowledge.

Crusius adds that not all collisions indicate fundamental restrictions of our knowledge, but some of them are generated by following principles that are not yet fully determined, so that we are not aware of all restrictions for their application. This happens, he suggests, when we are dealing with complex cases, where it is too hard to think all details at once and we have to just take the most usual details and abstract a universal rule from them, for instance, when in moral questions we cannot evaluate all factors, but have to assume a universal rule to decide at least something. Furthermore, Crusius notes, we might also just not have ever dealt earlier with cases where the restrictions of these principles become obvious: he gives as an example the development of Christian philosophy, where tenets of the religion have required the introduction of new restrictions to old principles followed universally by pre-Christian philosophers. Finally, Crusius points out the particular case of causal deduction, where we might still lack the full knowledge of some object and its influence, so that we are forced to be satisfied with what we have experienced and presume that things will follow the same course in the future.

Moving on to the collisions themselves, Crusius notes that they can involve formal principles used as signs for possibility, existence or connection of things. Such formal collisions happen especially in metaphysics, he adds, and they are the closest to the later Kantian antinomies. Crusius reminds the reader that these collisions always involve something more than just the law of contradiction, which allows no exceptions. Thus, the colliding proofs use principles that show something to be incomprehensible for us, although this incomprehensibility might just reveal the restrictions of the human mind. Crusius especially emphasises the force of obligation to decide, which of two seemingly equal proofs is to be accepted: for instance, he suggests, although the notion of freedom involves much that goes beyond our comprehension, we should accept it, because only freedom can explain the existence of divine law and moral guilt.

Crusius also thinks that the law of sufficient cause can never contradict the law of contradiction and proofs based on the first law are thus to be preferred over other proofs. For example, he explains, although the notion of creation of the world seems incomprehensible to us, we must accept it, because the world is such that it requires some ultimate causes.The final case of formal collision Crusius investigates involves using an otherwise reliable principle that in a particular context would force us to remove certain features of a thing, without which it could not be thought. For instance, he exemplifies, if we assume that a thing A can be divided infinitely, an actual infinite division would mean removing such intrinsic features of A, like its extension.

Just like some collisions involve just formal principles, Crusius explains, other collisions concern only the material propositions used in the proofs. Such collisions, he notes, occur when investigating efficient causes, especially in questions of morality. Crusius goes to great lengths to establish how to solve such moral dilemmas. To put it short, it all hinges on first analysing what justification each of the colliding proofs is based on and then finding out some principles of higher kind, on which to test the justifications of each proof. Even with this method, Crusius admits, moral collisions are often left undecided, because no satisfactory higher ground can be found.

Crusius, Christian August: Road to certainty and reliability – Analysing obscure propositions

Having investigated how to define and divide concepts, Crusius turns next to the question what applied logic has to say about propositions. He notes that most perfections and imperfections that propositions could have do not require specific rules, since they would concern the whole logic. The only topics left to consider in this regard, Crusius says, are rules for avoiding obscurity in propositions and rules for analysing propositions into their constituent propositions.

Starting with obscurities in propositions, Crusius notes the most prominent reasons why a proposition is obscure. These reasons include ambiguity of words and concepts belonging to two different genera. Crusius exemplifies the latter with one of his pet peeves: when we speak of grounds of something, we might be talking of causes or of existential grounds.

A specific case of obscurity Crusius mentions involves words indicating some quantity, like great or best. Such words create obscurities, he explains, if we do not have any clear measure to which to compare them (thus, if I say that this is the best world, this is still obscure, since we do not know on what scale this goodness is measured on). Even more obscure the case becomes, if instead of one quantity we have several and we do not know what it is we are talking about (for instance, if someone is said to have good memory, it is unclear whether e.g. they are quick to memorise things or whether they retain for a long time what they have memorised).

Moving on to the second topic or logical analysis or exposition of propositions, Crusius means by this showing what other propositions are thought at the same time when a certain proposition is thought distinctly. He notices at once that logical analysis does not mean going through all propositions that can be deduced from the proposition-to-be-analysed, if they cannot be thought with this original proposition. This does not mean that the propositions found through analysis need to be explicitly observable in the analysed proposition, Crusius adds: for example, although it is not evident from the form of the proposition, all real definitions include an implicit statement that the subject of the proposition exists or is at least possible. Similarly imperatives include also implicit propositions about the will of the speaker and often even indications of moral necessity.

Crusius, Christian August: Road to certainty and reliability – Divisions

After definitions, Crusius moves on to divisions, in which a more extensive logical concept (genus) is separated into narrower logical concepts contained in it (species and in rare cases even individuals) adequately, in other words, in such a manner that all individuals of the genus belong to one and only one of the divided species. Crusius is clear to distinguish division from mere distinction of concepts in general, which could be applied also to concepts that are not logical (say, when distinguishing cause from effect). He also points out the obvious fact that the divided concept is more undetermined and the narrower concepts go through all the possible determinations that could be attached to the divided concept.

Just like definitions, Crusius divides divisions into nominal and real kinds. By nominal division, he means an account of different meanings an ambiguous word has. In addition to this definition, nominal divisions are not of that much interest to Crusius, who deals more with real divisions, where species or individuals contained in an abstract concept are separated from one another. Crusius notes that real divisions come with four important elements: firstly, we have divided and undetermined general concept, secondly, the narrower concepts, into which the general concept is divided or determined, thirdly, the difference between the different members of the division or the narrower concepts, and finally, the point of division in the undetermined concept, to which the narrower concepts or separated species relate as further determinations. Crusius states that this point of division can be an existential or causal abstraction, and in the former case, an external or internal abstraction.

Crusius points out many reasons why we need to make divisions, first of them being that division brings abstract concepts closer to practical applications. Furthermore, he adds, if we did not have a clear idea of a hierarchy of a general concept dividing into many species, we would have to make do with mere individuals, with no idea of their commonalities, thus being deprived of many important truths. Yet, the main use Crusius envisions for divisions lies in their application in disjunctive deductions.

Crusius goes through the most prominent classifications of real divisions. Thus, real divisions are either divisions of logical oppositions or divisions of real oppositions and also either divisions of contraries or divisions of contradictories. Furthermore, Crusius notes that if we compare divisions applied to the same general concept, these alternative divisions can be subordinated – one division applies the other division and then divides its members further – or coordinated, that is, made according to completely different schema.

Besides these classifications, Crusius hands out some rules, such that the point of division should optimally be essential to the divided general concept and that in choosing from different alternative divisions, we should consider what is the most useful of them. Finally, he shares some methods for finding divisions, such as following experiences of differences or going through possible determinations and causal connections of the general concept to be divided.

Crusius, Christian August: Road to certainty and reliability – Definitions

If in the previous chapter Crusius dealt with the application of sensations and experience, he now turns his attention toward abstract ideas, which due to their non-concreteness are prone to confusion and might even not correspond to anything existent. Thus, he argues, abstract concepts should always be defined. By definition Crusius means a method of making objects of an abstract concept distinguishable from other objects. Definition needs therefore not reveal the fundamental essence of a thing. Still, it is something more than mere description, which just collects some distinctly abstracted predicates of a thing, which still are not sufficient to distinguish the thing from others, except perhaps in some limited context.

Crusius goes on to indicate some basic rules about definitions. Definition, he says, should contain only concepts that belong to the defined object always and are thus logically essential to it. This means that the concepts contained in a definition are either genera or propria, which in case of definitions are usually called specific differences. Furthermore, Crusius continues, these logically essential concepts can be either essential as such to the object defined or just natural, which then have to be used sparingly and always with the appropriate restriction that they belong to the object regularly and are lacking only in extraordinary cases. Some of the logically essential concepts, he adds, are essential to the object in themselves, but others only when we suppose the existence of the world.

Parts of a definition, Crusius explains, must be more distinct than the defined object, in other words, obscure concepts should not be defined by other obscure concepts. Especially metaphors and circular definitions should be avoided. Even so, he admits, the parts of the definition need not be fully distinct, just more distinct than the object defined. Crusius adds also that a definition must be adequate in the sense that it contains all the same individuals as the defined concept and nothing more.

Crusius divides definitions according to their purpose: the purpose of a nominal definition is to explain what a word means through an abstract idea separated into its constituents, while the purpose of real definition is to transform an obscure or at least concrete concept into an abstractly distinct and adequate concept. A clear consequence of these explanations is that the same definition can be nominal and real, depending on its purpose.

Starting with nominal definitions, Crusius notes that they should be used to define something possible, because it would be of no use to have a word that refers to something that could not be thought. Indeed, he adds, nominal definitions should in general be useful, which implies that they should not give occasion to error and confusion and should conform as much as possible to ordinary language Crusius emphasises also that nominal definitions can be used only to deduce nominal conclusions, how a word can or must be used.

Crusius divides real definitions into ideal definitions, which define only something possible that need not exist, and real definitions in the strict sense, which transform a concrete idea of an existing thing into an abstract and adequate idea. Beginning with ideal definitions, he notes that they are not to be confused with nominal definitions, which define only a name of something. Still, they are also not yet real definitions in the strict sense, because they cannot be used to deduce what really is or is not, but only hypothetical conclusions: what must be affirmed or denied when we presuppose the existence of objects corresponding to this concept. Of course, if we show that there exists something agreeing with the ideal definition, we have made it a real definition. Crusius also notes that in pure mathematics ideal definitions are always real definitions, since this discipline investigates abstract possible magnitudes with their properties and relations.

Real definitions in the strict sense, finally, are divided by Crusius into fundamental or first concepts and deduced or further definitions. By a first concept he means a definition that we can know without presupposing a proof from another definition. Crusius emphasises that a first concept is thus first only for us and need not be a natural ground for all other properties of a thing. Indeed, he adds, there could well be many first concepts, depending on what characteristics is our starting point for abstractions.

It depends on the thing in question where we should find their first concepts, Crusius explains. With physical, non-artificial entities (e.g. natural bodies and souls), the crucial question, according to him, is whether they are sensuous or not: with the former, the sensations provide us enough first concepts, while with the latter, we must just begin with the most undetermined idea. With artificial entities, the first concept is provided by their method of generation, and if they particularly are mechanical entities, the first concept is given by their immediate purpose and the structure required for this purpose. With moral entities (e.g. obligations and rights), Crusius notes, their first concept is defined by their purpose. Finally, he concludes, God and their activities can be defined only by symbolical concepts, indicating negatively what they are not, or pointing positively to their effects and to very indeterminate abstractions common to all things.

An important point for Crusius is that we should always demonstrate that a first concept does really refer to objects beyond our thought (if we couldn’t do that, it wouldn’t be a real definition, but only nominal or ideal). He does explain that in some cases we might not be speaking of physical, but of moral existence, in other words, that something should be the case (this is evidently what we should prove of moral entities). In any case, the proof can happen a posteriori from experience or a priori from connections between concepts or grounds.

The final type of real definition – that of further or deduced definitions – includes, Crusius says, many useless explanations that really add nothing to the first concept and even confuse what is meant with them. He delineates two useful kinds of deduced definitions, namely explanations of the essence of things, which serve to uncover the fundamental nature of the thing defined, and characteristic definitions, which help to distinguish individuals belonging to the defined class from others.

Starting with the explanations of the essence of things, Crusius notes that they might provide the physical ground – fundamental forces that constitute the defined thing – or the moral ground – explanation why the defined thing should or is allowed to exist (the traditional explanation why God allows the existence of sin is of this kind). In searching for these explanations, he adds, we might either start from a sensuously given first concept and then move to the grounds explaining these sensuous properties, or then we can start from an undetermined first concept of a non-sensuous or a moral thing and determine it in more detail.

Ending his discussion with characteristic definitions, Crusius explains that they are required, whenever the first concepts do not give us enough criteria for deciding how to apply these concepts. Examples of such characteristic definitions are criteria for deciding when something is true or false, criteria for deciding when some law applies, or criteria for recognising the existence of non-sensuous entities from their effects.

Crusius, Christian August: Road to certainty and reliability – Experience

Crusius sets out as the aim of the practical part of his logic to show how to apply the capacities of understanding for knowing the truth. In order to do this, he explains, we must investigate, on the one hand, sensations or experiences, and on the other hand, judicious use of abstract ideas (memory and ingenuity, he thinks, require no rules). Starting from experience, Crusius notes that the word can refer to two things: to a certain kind of proposition and to an act of experiencing. He mostly deals with the propositions of experience, having only few things to say about the act of experiencing, and I will also focus on the former.

As a proposition, Crusius continues, experience means an immediately sensed connection of subject and predicate. Depending on the kind of sensation, the experience can then be either external or internal. Crusius underlines that internal experience should not be confused with axioms or immediate propositions. We are conscious of all propositions through internal sensation, he explains, but only such propositions are axioms, where we immediately sense an essential connection between the subject and the predicate, so that when the predicate is denied, the concept of subject must also disappear. On the other hand, a mere internal experience is a proposition where the subject and the predicate are internally sensed as existentially connected.

Although it would be natural to assume that in all experiences both the subject and the predicate would have to be sensuous, that is, ideas generated through sensation, without the aid of any abstraction, Crusius notes that we can sense also a mere existential connection of such objects that are thought through abstract ideas. Thus, he divides experiences into common and reflecting experience, based on whether the subject and the predicate of the experience are sensuous or abstract.

Crusius states that the certainty of the propositions of experience are shown by his earlier demonstrations about the certainty of our sensations. Of course, he adds, it is still a possibility that what we think is a proposition of experience contains something else, for instance, imaginations and even outright impossibilities, connected to obscure and incomplete sensations. Thus, Crusius concludes, we need some rules to decide when we have a true proposition of experience in front of us. Thus, while experience teaches us that in certain circumstances certain representations are generated in us, a proposition stating that something existing is connected with these representations is already dependent on further deduction. Other clear instances of propositions that cannot be propositions of experience, according to Crusius, are negative propositions (experience can only tell that we do not sense something), causal propositions (experience can only show connections between representations) and universal propositions (abstractions cannot be sensed as abstractions).

Crusius continues by noting that, according to experience, we do not sense simple substances nor their fundamental forces. This means, he explains, that we cannot sense the fundamental essence of anything, since things are divided into abstractions, simple substances and complex substances, out of which we can sense only the last one, and even in their case we cannot sense how they consist of simple substances, which we would have to do, in order to sense their essence. Many of seeming propositions of experience, Crusius concludes, are then only mixed experiences, that is, they require something added to sensations through proofs.

Crusius, Christian August: Road to certainty and reliability – Corrupted understanding

We have reached a milestone in the logic of Crusius, since we are now about to turn to its practical part, where the question is not so much about the structure of the capacities and activities of human understanding, but of the proper way to use them. The first topic to be covered in this practical part, Crusius says, is that of the diseases of understanding, that is, not just temporary errors, but constant conditions hindering the understanding from its proper purpose of knowing what is true.

Crusius thinks it evident from experience that human understanding can have diseases in the sense just mentioned. Furthermore, he identifies three causes for these diseases. Firstly, because understanding is subservient to the will, the will can through a repeated bad use of understanding create harmful habitual dispositions. Secondly, Crusius continues, the body restricts the activities of thinking, and if it repeatedly makes thinking difficult, it can create constant bad qualities in understanding. Finally, the human soul is conceived through external causes, which can create many innate imperfections in understanding.

Despite admitting the possibility of human understanding becoming diseased or corrupted, Crusius denies vehemently that such a disease could affect its essence. After all, he argues, God created the essence of understanding, so that it must be good. This is no contradiction, Crusius assures the reader, since it is as true as eyes being by their essence the vehicle for seeing, but sometimes having maladies that impair the vision. Thus, Crusius concludes, the diseases of understanding can concern only its grade or relations to other things.

Crusius divides diseases of understanding into two classes: physical weakness of the fundamental forces of understanding, and faulty state of understanding in relation to its use. Starting from the first option, Crusius divides weakness of the force of understanding into absolute and relative weakness. Of the two kinds, absolute weakness is measured by the inability of the understanding (or one of its capacities) to fulfill its purpose. Relative weakness, on the other hand, describes a situation where two capacities of the understanding – usually what Crusius calls lower and higher faculties – reverse their customary roles, so that a lower faculty escapes the regulation given by the higher faculty of understanding.

Crusius divides the second class of diseases of understanding – those pertaining to the state of understanding in relation to its use – into further kinds. Firstly, there are all the faults pertaining to attention, such as the lack of external or internal attention, purposeless attention or attention for worthless causes – Crusius underlines that a conscious ignorance of things should not be included in this group, and indeed, is a fault only if what is ignored is something useful or something that we are obligated to know. Secondly, there is the incapacity to think many things at the same time, whether because one cannot represent many ideas at once or because one cannot make many abstractions at once. Thirdly, there’s the inability to continue mediation for a long period in a row. In the fourth place, Crusius mentions doubt and lack of constancy in assent, but also the opposite failures of carefree assent and stubborn adherence to an assent once given. Finally, there’s the too great dependency of the understanding on the heightened activities of will.

All the described diseases of understanding, Crusius thinks, have detrimental effects: they make our observations faulty and concepts obscure, they make us confuse objects with one another and imaginations with sensations, they hinder us from concluding our thoughts, and top it all, the more they affect us, the more habitual they become. No wonder then that Crusius gives a long list of means for curing these diseases, most of which are easy to comprehend, such as practicing continuous thinking. As a main cure Crusius recommends virtuous disciplining of understanding. He notices a potential circle – understanding cannot be improved without virtue, but virtue cannot be improved without understanding – but thinks this circle is not fatal, because even a small step towards better in one leads also to improvements in the other.

In addition to morality and virtue, Crusius connects his account also with religion, pointing out that even the Bible recognises the corruption of the human understanding and the beneficial effects of morality on it. He is also quick to emphasise that the Bible does not condemn reason and understanding as essentially faulty. Even further, Crusius suggests that the fear of error should make us eager to search for divine providence, especially in matters involving our own happiness. Still, he underlines, curing the corruption of understanding can never be forced upon anyone, but always requires internal activity of the person in question.

Crusius, Christian August: Road to certainty and reliability – Certainty and assent

Crusius defines certainty as a condition where a thinker has no more any fear that the opposite of something that they posit of an issue would hold. Such certainty can be true, so that what the thinker posits as true is true and is also held to be true due to such reasons that can be signs of truth. Then again, Crusius adds, certainty can also be just seeming, so that either the propositions posited are not true or that the reasons why we are certain of them are not valid – or even that neither holds. Crusius also distinguishes objective certainty – existence of a thing, insofar as we regard it as something that can be known certainly – from subjective certainty, that is, certain knowledge that an understanding person has of such a thing.

Crusius aims to find the answer to the question how it is possible that we can become certain of anything. He thinks that God knows all things by the infinite perfection of the divine essence, while it is still a conundrum how humans find subjective certainty and how such subjective certainty can be true. Crusius starts to resolve this conundrum by first noting that in some circumstances we are forced to take some propositions as certain. This compulsion is generated either immediately – he mentions as examples experiences and highest fundamental propositions of reason and immediately obvious axioms – or mediately through a perceived connection of a proposition with immediately certain propositions. The mediating connection, Crusius reminds us, can happen through demonstration or through infinite probability, that is, a state where each new evidence appears to inevitably point to a certain direction.

The certainty of both the immediately certain propositions and of the methods of demonstration and probability, Crusius argues, are ultimately based on the three fundamental propositions – or even on the highest fundamental proposition of contradiction. The proposition of contradiction is then, for Crusius, the form of all human knowledge, while its matter is provided by sensations of the objects of knowledge. Moving downwards from this pinnacle of human certainty, Crusius divides certainty into demonstrative certainty, based on the method of demonstration, and moral certainty, based on the method of probability. Demonstrative certainty divides further into geometric certainty, based merely on the proposition of contradiction, and disciplinary certainty, based also on the two other fundamental propositions: while demonstrative certainty is based on a principle allowing no exceptions, the principles of disciplinary certainty have their restrictions that we have seen earlier.

Crusius notes the sceptical worry that the just described certainty might be only a delusion. Yet, he points out, sceptics themselves must unavoidably think of certain things as true – they sense that they doubt things, and because doubt is a form of thinking, they sense themselves thinking, and they are aware of thinking certain issues. From this sensation of their own thinking, Crusius continues, they can abstract the three fundamental propositions of reason and they must find them and anything derived from them necessarily compelling. Now, a sceptic might answer that they do admit their own existence and perhaps even the proposition of contradiction, but they still doubt all the other fundamental propositions and sensations. Crusius accuses such a sceptic of partiality: the feeling of compulsion is the same in all these cases, so why prefer some over others?

Crusius also has some pragmatic arguments against scepticism. Since sceptics really do not want to admit the certainty of the methods of deciding what is true, he argues, they must act foolishly in their practical affairs – or more likely, they just forget their scepticism and use the methods to decide what is good for them. Similarly, Crusius sees sceptics as necessarily denying the validity of all legal and moral obligations and religion. Indeed, Crusius accuses, scepticism is often motivated by a godless fear of what their own conscience dictates, if it is not just a sign of laziness.

What the consideration of scepticism has shown, Crusius states, is that our certainty is ultimately based, on the one hand, on the physical inclination of our understanding to accept certain things as true, and on the other hand, on the obligation to prudently do what is good for oneself and thus to find out what truly is good. Both these routes, he suggests, point toward God as the original source of all truth: because God has created us in a certain manner, we are compelled and obligated to recognise something as true. Human knowledge, Crusius says, is just an image of divine understanding and is true insofar as it is similar to divine knowledge.

Crusius returns to the concepts of the form and the matter of human knowledge. We have seen, he states, that all the formal principles of human knowledge are certain, since its highest principle and all methods based on it are certain. Similarly, Crusius adds, its material principles, or experiences provided by our senses and axioms abstracted from these experiences, should also be certain. This is evidently clear of the axioms, he posits, because they are immediately based on the highest propositions, but the question of the certainty of sensations must be dealt with separately.

Crusius defines sensation as a condition of understanding where we are immediately forced to think something as existing and present. He divides it into external sensation, where we sense something outside our soul, and internal sensation, where we sense something within our soul. If the sensations are to be true, Crusius argues, we must, firstly, be able to distinguish sensations from other thoughts with certainty, secondly, it must be certain that if we sense, an object of sensation exists, and finally, it must be certain that what we sense of an object actually describes it. (An observant reader might notice that as is often the case in this book, Crusius is following his teacher, Hoffmann.)

Starting with the first problem, Crusius notes that a sensation is distinguished by a feeling of being compelled to admit the existence of something, and insofar as there is such a compulsion, it is certain that we sense. If the sensation is lively enough, the compulsion is so perfect that it is impossible to deny that we sense, while even a lesser grade of liveliness might make us morally certain, if it is backed up by other sensations and reflection of already known truths. Crusius admits that we sometimes confuse other mental states with sensations, such as vivid imaginations, dreams and hallucinations during illnesses. Still, he ensures the reader, all these states can be distinguished from true sensations, if they are just made distinct enough.

The next question is whether sensations have objects beyond the sensations themselves. In the case of internal sensations, Crusius thinks that they compel us so greatly and immediately that we cannot doubt that such a state of mind exists in our soul. He mentions that idealists doubt the existence of the objects of external sensations and accept as certain only the existence of either spirits in general or merely of their own spirit. Crusius relies again on the argument of partiality: why should we accept the existence of ourselves, but not of anything beyond ourselves, if the feeling of compulsion occurs with both internal and external sensations? He adds the pragmatic argument that an idealist is a fool if he argues with someone they don’t believe to exist.

All the arguments thus far presented for the existence of external objects do not rely on the existence of God, Crusius notes and adds that the case is even clearer if we do accept God. After all, if God has given us external sensations, they must be able to reveal something in correct circumstances. Indeed, Crusius adds, the existence of matter adds to the perfection of the world and thus reflects the perfection of its creator. He also finds here a weapon against the Leibnizian hypothesis of the pre-established harmony, since this hypothesis makes the creation of the material world seem useless, denying any possible interaction between what is sensed and the person sensing. Crusius even suggests that we can thus assume the action of some external object as a condition of external sensations.

The final question about the sensations is how much of what we sense actually pertains to the objects of the sensation. Crusius admits that even if sensations were true, what we sense need not always characterise the objects sensed, for instance, green colour might not be something in grass. Then again, he points out, when we say that something is green, we merely mean that it looks green. Thus, it doesn’t affect the truth of senses that things seem different in different circumstances, because circumstances affect the interaction of the object sensed and the sensory organs. According to Crusius, we can only say that the objects in certain circumstances are the causes of certain representations and that in the same circumstances they generate the same representations and thus corresponding sensations. He does also admit that especially visual sensations provide us with intuitive knowledge about issues pertaining to the sensed objects, namely, in case of their figure and motion.

Crusius notes that we still have to consider the topic of assent, that is, we are not to merely discuss when we should take something as true and certain, but also when we do and can take something as true and certain. Assent, he explains, is not a matter of understanding, but is also dependent on our will. True, Crusius admits, it is not completely in our own power to decide what to assent to, since forceful enough reasons compel us to assent (he also points out that assent cannot be forced by external causes, but can only be compelled by reasons). Still, assent is also dependent on will in the sense that it decides where and in what measure we exert our understanding. Thus, we can hinder assenting to a truth through insufficient consideration of the grounds of knowledge. We can even generate an unreasonable assent by confusing inadequate with adequate grounds or by relying on very small probabilities due to our desires and decisions.

This concludes the theoretical part of the logic of Crusius. Next time, we shall begin tackling the practical part.

Crusius, Christian August: Road to certainty and reliability – Probability

Until now, Crusius has dealt with demonstrations, where, he says, all alternatives are refuted as unthinkable, until only one remains. Now we are about to start the study of the method of probability, where a proposition is held to be more true than false or even fully certain, but alternatives or opposites can still be thought of. Crusius divides probability into three species: verisimilitude or what is more clearly possible and more to be assumed true than its opposite, reliability or what deserves to be taken as true in such a measure that one could act on it without further consideration, and moral certainty or what we consider to be undeniably certain, even though we can think of its opposite.

Crusius notes that reasons for taking something as probable can be cognitive in the sense of concerning just the characteristics of propositions and their relations toward other propositions, while some reasons concern also the connections of things with purposes. Starting with the merely cognitive reasons, Crusius considers the matter of probability, from which probable propositions are made, that is, logical possibilities or propositions that cannot be demonstrated true or false – he adds that actually even demonstrated propositions can be considered logical possibilities, if we ignore their demonstrations.

Crusius divides logical possibilities into perfect logical possibilities, where we understand how the predicate can be true of the subject, and imperfect logical possibilities, where we cannot understand this, but observe no contradiction in combining the predicate with the subject. Perfect logical possibilities have two levels, depending on whether we understand the possible connection of the subject and the predicate through an observation of an actual example or through mediation of other ideas. Crusius also distinguishes true logical possibilities from apparent or verbal possibilities, where at first sight the proposition seems to be irrefutable through demonstration, although further investigations show otherwise. Furthermore, he distinguishes logical possibility of propositions from metaphysical possibility of a thing that can be thought of, but might not exist.

How probable propositions can then come out of logical possibilities? Crusius notes that if we cannot prove a proposition, we are inclined to doubt its truth and even deny it. Then again, if the opposite of this proposition assumes even more without any proof, this makes us more inclined to reject the opposite. Then the original proposition is deemed probable. The fundamental essence of probability, Crusius says, is thus that a logical possibility assumes less without demonstration than its opposite. In other words, all probability is generated from the improbability of the opposite.

Crusius notes that sometimes the reason for assuming the probability of a proposition lies only in the subjective circumstances of the individual thinker: then we are dealing with subjective probability. Then again, the reason might also lie in the nature of things and the universal essence of reason and then we are dealing with objective probability. Thus, Crusius argues, subjective probability often vanishes with a more thorough investigation, for instance, when we find new alternatives we have not investigated, while an objective probability must remain constantly probable.

Crusius divides probability also to common and learned probability, depending on whether one only indistinctly feels the reasons for taking a proposition as probable or knows them distinctly. Furthermore, the learned probability has, he says, two different levels, depending on whether we can give the reasons of the probability only according to matter or whether we can evaluate it also according to form, that is, whether we can recognise the logical signs of probable and take them even to the highest grade of probability. By these logical signs of probable, Crusius appears to refer to rules, by which to determine whether something is probable. Just like with rules of deduction, I shall mostly just list them, using the six categories Crusius classifies them into.

Rules belonging to consideration of multifaceted possibility

1) The basic rule of this category: something that can occur in many different manners is more probable than something that can occur in less manners (e.g. because there are more ways to lose than to win a tournament, it is probable that our team will lose it)

2) If one of many possible alternatives must be true, the probability of one alternative is less, the greater the number of other possibilities (e.g. the more there are teams in a tournament, the less probable the win of our team is)

Crusius notes that both 1) and 2) work as stated, only if there are no other reasons that will change the scales between the alternatives, for instance, when a number of attempts is multiplied (e.g. if our team takes part in several tournaments, the probability it will win at least one of them increases).

Rule of consideration of chance coincidence of possibilities

3) A proposition that assumes the co-occurence of many possibilities by chance is improbable. Crusius notes that this rule does not work, if the proposition speaks of deliberately arranged coincidences. Furthermore, he admits that chance sometimes imitates foresight, if the number of attempts increases indefinitely.

Rules belonging to the consideration of more real possibility

4) The basic rule of this category: the more real possibility is probable. By a possibility being more real than another Crusius means that more of the causes and circumstances required for the existence of the possibility are already known to exist and can be presumed as existing. These causes and circumstances can also include signs of things, such as their effects, and partly even our thoughts of them, so that we can know at least their possibility through our understanding of them, and the more distinctly we understand the issues in question, the greater their possibility, which leads to further rules.

5) If we distinctly understand the way in which a predicate belongs to a subject in a possible proposition, the proposition is more probable than if we do understand this (e.g. a mechanical explanation of a physical phenomenon is more probable than an explanation through unknown forces).

6) If we already know an example where the possible proposition is actualised, but the same is not true of any of its alternatives, this proposition is more probable (e.g. if we know how a phrase is to be interpreted in one passage, it is probable that it will be interpreted in a similar manner in another passage).

7) The more we already know of the parts of what is assumed in a proposition or of the existence of their cause, the more probable this proposition is (e.g. if we can explain a phenomenon through known causes like air and salt, it is probable that no hidden causes are required to explain it).

8) If we know of only one alternative possibility and if it is improbable that we would have missed a possibility, then this possibility is probable. Crusius underlines that this rule leads to objective probability, only if we have so much experience of the issue or so much practice for this type of thinking that we can presuppose that it would be too great of a coincidence that only a single possibility would occur to us (thus, if we are not doctors, we should not say that the only cause of sickness we can come up with is the probable one).

9) If two things seem to be similar or dissimilar and it is improbable that we should find no reasons to suppose otherwise, their apparent similarity or dissimilarity is probably true.

Rules belonging to the expectation of similar cases or analogy

10) The basic rule of this category: what has been constantly encountered is also probable in all other and future cases, insofar as it is probably based on a common essence or a constant external cause. Crusius notes that the restriction of the conditional clause to probabilities is important, because otherwise we would be dealing with a demonstration. Furthermore, he adds, the rule is also based on another probability, that is, that we have experienced enough examples to draw the probable conclusion. Finally, Crusius notes, the conclusion cannot be made without the assumption of common essence or constant external cause (e.g. although I would have won all the poker games thus far, there is no guarantee that I will win the next one, since winning poker games is not part of my essence nor guaranteed by some constant cause).

11) If we have encountered something often, it is probable that we will encounter it many times in the future, as long as we cannot state any reason why it would be at least as possible that it would happen otherwise in other cases. Crusius notes that this probability is at least subjective, but it can be also objective, if there are good reasons to assume that it would be highly improbable that we would have experienced only examples justifying the probability.

12) What we have most often encountered in earlier examples is to be expected more than its alternative in any individual case.

13) What we have perceived to occur in one exemplary case occurs probably at least most times also in other cases of the same kind, insofar as it is probable that the similar cases have similar sufficient causes. Crusius notes again that if the conditioning clause would not be probable, we would be dealing with a demonstration. Furthermore, he points out that this rule presupposes the use of two other rules: we must use rule 8) to conclude that the sufficient cause we have envisioned is probably the only possible explanation, and we must use rule 9) to conclude that the cases are probably similar.

Rule or the consideration of conflict with known causes

14) What conflicts with existing sufficient causes is improbable.

Rules belonging to the correspondence with phenomena or circumstances

15) If a possible proposition corresponds with already known phenomena better than its alternatives, it is thereby probable. Crusius defines phenomena as something that is already otherwise known demonstratively or probably and that has a possible causal connection with what is assumed in a possible proposition, which is then called a hypothesis. Crusius divides phenomena into two kinds: mere phenomena that just possibly corresponds with the hypothesis and harmonious phenomena that agree also with one another and must therefore be derived from a single hypothesis.

16) Hypothesis based on two harmonic phenomena is more probable than alternative hypotheses based merely on a number of mere phenomena.

17) If we must count the phenomena backing the hypothesis up, we must divide the phenomena into smaller phenomena that can exist without other phenomena (thus, phenomena that are intrinsically linked to one another must be thought as a single phenomenon).

18) When counting harmonic phenomena, the correspondence of the phenomena creates a new phenomenon backing up the hypothesis (in other words, adding another harmonic phenomenon to a known phenomenon already raises the sum of the phenomena into three, because we have a) the original phenomenon, b) the new phenomenon and c) the correspondence between the phenomena).

Crusius points out that not all phenomena are of equal strength, because some of them may have internal weaknesses that cancel their power to prove things. He identifies three possibilities that can create weaknesses: the matter of a phenomenon might be uncertain, the possible causal connection between the hypothesis and the phenomenon might be uncertain, and the phenomenon might concur as well with other possible hypotheses.  Hypotheses, Crusius continues, can also have their weaknesses or difficulties, if they conflict with actual circumstances. In order to avoid difficulties, he explains, we can sometimes add subsidiary hypotheses. Such an addition makes the hypothesis a more complex possibility and thus sometimes also more difficult to prove.

Having gone through the various rules for deciding that something is probable, Crusius notes that they can be applied either to individual or to universal propositions: in the latter case, the probable proposition is called a presumption. Thus, Crusius divides all probabilities into presumption probabilities, which are proven by subsumption to a presumption that has been proved earlier, simple correspondence probabilities, which are known through a correspondence with the phenomena, and mixed cases involving both kinds of proofs.

An important type of presumptions are logical presumptions, which are the most general types of presumptions related to the first five of the six rules of probability:

1. presumption or rarity (we presume improbable what happens only in rare cases),
2. presumption of miraculous chance (we presume improbable what involves a chance coincidence of many possibilities)
3. presumption of more real possibility (we presume probable what is most real) and its subtypes, presumption of sufficient cause (we presume that an effect will follow an unhindered sufficient cause), presumption of unapparent cause (in issues we are experts, we presume improbable what has no causes) and presumption of deficient power in given cause (we presume improbable what the well-known given causes have no power to produce)
4. presumption of analogy of perpetual and frequent (we presume probable what we have encountered perpetually or frequently) and the presumption of uncommon, divided into presumption of fully uncommon (we presume improbable what we have never witnessed) and the presumption of rare (we presume improbable what we have rarely witnessed), and 
5. presumption of repugnant or unnatural (we presume improbable what is opposed to existent and sufficient causes).

Crusius still goes through methods for deciding what to choose when different rules of probability contradict one another – in essence, these methods rely ultimately on the very notion of probability. I shall already move on to the next subject, that is, the additional weight of non-cognitive issues or purposes and goals in deciding what is probable. Crusius notes that this new weight might be derived either from obligations involving prudence (do this if you want to achieve that) or from obligations of moral law (do this in order to follow the will of your ruler). In the first case, he explains, it might be prudent for us to act according to what is probable, while in the second case, we might be obligated to act according to what is probable. This is especially true when the probability is what Crusius calls infinitely large, when we can be certain that any future evidence will just reveal examples justifying its probability.

Crusius suggests that God specifically intended the humans to have only probable knowledge of certain key truths. Firstly, he explains, this is due to essential limitations of human nature, but secondly, God also wanted us to fulfil the duty of trusting God with less than perfect knowledge of the things. Indeed, Crusius thinks, even our belief in the veracity of demonstrations is often based on probability, especially if the demonstrations are very complex: we might have made an error following the demonstration once, but it is improbable that we have gone through its details many times and always found it convincing. In fact, he concludes, we often find probable arguments more convincing than demonstrations, since a single fault in our line of reasoning will make demonstration faulty, while probable arguments depend on an accumulation of many facts speaking for the intended conclusion, so that even if one supposed fact is revealed to be faulty, the whole argument does not stand on it alone.