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.