Reduction of physics

At least since Aristotle's Posterior analytics, mathematics has been the model of science, in which everything should be deduced from self-evident axioms and definitions. Indeed, mathematics was quite long considerably more advanced and certain than any other field of research. It is then no wonder that Descartes tried to fit physics and especially mechanics into this model. Even more, he suggested that basic laws of mechanics could be derived from mere geometrical considerations: after all, matter was defined by extension, so the characteristics of the motion of matter should be reducible to the extensional characteristics of matter, such as size and velocity.

What Descartes had failed to take into consideration was that the nature of matter is not exhausted by its extension and that it cannot be identified with mere space. Thus, one had to take into account also the mass of bodies, when considering e.g. how two bodies behaved in a collision. Recognizing this made it a necessity to empirically observe the actual movement of bodies and to look for regularities that could be generalized from these observations. Inconsistently, such studies were still often called mathematical and even a semblance of mathematical deduction was upheld.

Followers of Leibniz in Germany were more aware of the inability to reduce physics to mathematics. Hence, we see Christian Wolff admitting that his cosmological considerations had an empirical basis and that reliable experiences in general must supplement the inabilities of human understanding. In light of the empiricist tendencies of Wolff, it is interesting to see that Bilfinger supposed that it might be possible to derive basic laws of physics apriorically. I do not think Bilfinger is necessarily going against Wolff, but merely explicating the Wolffian position from a different angle: true, in practice we must use empirical method, but in principle we should be able to use deduction.

Bilfinger still doesn't advocate a return to supposedly geometrical demonstrations of Descartes. Instead, he supposes laws of physics should be derived from metaphysics. In other words, Bilfinger doesn't want to state that physical laws would be necessary like laws of logic and mathematics. Instead, they are based ultimately on the decision of God. According to the Wolffian position, God has created the best out of all the possible worlds. Hence, all the laws that the world follows must also be as perfect as they could be – and if we knew what is objectively best, we could know the laws chosen by God.

What Bilfinger's position makes clear is the contingency of physical laws. Specifically, the creator of the laws still holds the power to suspend these laws for a limited period and place. In common parlance such local suspensions of laws are called miracles. In effect, Bilfinger is saying that miracles are possible and that God has power to make them – another defense of Wolff against suggestions of atheism.

So much for physical laws, next time I shall deal with the difference between intuitive and symbolic cognition.

Georg Bernhard Bilfinger: The harmony between human soul and body, altogether pre-established, out of the mind of illustrious Leibniz, hypothetically studied (1723)

It is no wonder if you don't remember Bilfinger, because the first work I read from him was short, immemorable and not very original. Although Bilfinger won't get any points for originality this time either, at least the topic is of a more general interest. Like the name says, De harmonia animi et corporis humani, maxime praestabilita, ex mente illustris Leibnitii, commentatio hypothetica aims to examine the theory of the pre-established harmony. Leibniz himself had spoke of harmony between all substances whatsoever, but Bilfinger here concentrates on the particular case of souls and bodies. Bilfinger follows here the example of Wolff, who had already had some reservations on the full Leibnizian theory of monads.

Bilfinger starts from ths established fact that bodies and souls do work in harmony. When an object is brought in front of my eyes, I experience usually a visual sensation corresponding to the object. Similarly, when I have a volition of moving my hand, the hand in fact moves. Thus, the causal series governing bodies and causal series governing souls reflect themselves partially.

Bilfinger considers quickly the possibility that at least one of the series would consist of necessary processes. For instance, Spinoza thought that the series of both bodily and mental events followed necessarily from the eternal essence of God. Bilfinger disregards this option, because the two series do not seem necessary – I could have walked somewhere else etc.

Bilfinger suggests there are only three possible ways to explain the harmony between the two contingent series. Firstly, there could be true causal influx between the two series – this is the common sense explanation. As Bilfinger notes, the influx theory goes against certain assumption of modern science. Observations appear to show that material objects retain the quantity of their motion, unless they interact with other material objects – they either share some of their quantity of motion with others or receive some quantity from others. Because soul doesn't move, it cannot impart motion to material objects, not even to its own body, and cannot thus make the body do anything.

Descartes' stance on the issue was ambiguous. He did accept the physical fact of the stable quantity of motion, but suggested that the soul might still change the direction of movement of the body or some part of it. By the time of Leibniz, it had become evident that this solution would not do – material objects retained also the direction of their motion, unless the direction was changed by the force of other material objects.

The Cartesian school had then slowly turned towards a new explanation. They suggested that whenever body appeared to do something to soul or vice versa, God on this occasion decided to interfere in the causal chain and connect the movement of the body with the respective change in the soul and the change in soul with the respective movement of body. This occasionalism had the setback that it appeared to break the ideas of modern science even more than causal influx. If occasionalism were right, there would be no true causal regularities, but everything would depend on the will of God, who would be constantly making miracles to sustain his creation.

Leibnizian solution is then that God has preordained souls and bodies to work in harmony, like two clocks that a perfect watchmaker has winded up show always the same time. Bilfinger notes that the thesis of pre-established harmony has justification enough in the fact that all other options fail to meet the standards of modern science. Still, he also notes that the harmony becomes an immediate corollary if we just accept other aspects of Leibnizian metaphysics – if souls are monads representing everything and especially the group of monads that constitutes its body, then the representing soul and represented body necessarily work in harmony.

All the previous is pretty straightforward summarising of Leibniz's thoughts. More original are Bilfinger's attempts to answer objections presented against the theory. A good representative of those objections come from Pierre Bayle, the skeptical encyclopedist. Bayle had accused Leibniz that his theory leads to materialism, because he must assume that bodies can run their own course, without any guidance of souls – my body could be writing these apparently reasonable words without me being aware of it. Bilfinger notes that even such complex phenomena like the movement of the planets can happen without any governing soul. Furthermore, he emphasizes that the world still isn't necessary substance of Spinoza, because it has been created by God. Finally, the independence of material world still wouldn't lead to a denial of souls, because mere material things couldn't represent anything – here Bilfinger is following Wolff.

Bayle had also ridiculed the notion of a causal series of the changes of soul. Bayle compared monads with atoms and assumed that monads would also be governed by similar iron laws. Furthermore, he wondered how sudden changes in the experiences of soul could arise, for instance, how could such complex phenomenon like music suddenly appear in our minds. Bilfinger emphasizes the importance of obscure representations in the life of a soul. These obscure sensations make our experiences so varied and thus differentiate monads from simple, featureless atoms. They also help us to understand sudden changes in our mental life. These changes have built up gradually, but only through unaware representations. Only when a certain threshold had been passed will the symphony start to play in our minds.

Even more interesting are Bilfinger's attempt to answer objections he has heard from his own acquaintances. For instance, Bilfinger has to explain why sickness of the body limits also the capacities of soul. Bilfinger notes that this is just natural – because soul is in harmony with the body, the soul sure must follow what the body does and act confused, when the body is ailing. Furthermore, Bilfinger explains that the sequence of ideas in soul must correspond to some movements in brain, which are capable of producing movements of body that appear rational. In effect, theory of pre-established harmony could be reconciled with the idea of human actions being dependent on brain.

So much for pre-established harmony. Next time we'll begin a summary of Wolffian philosophy.

Andreas Rüdiger: True and false sense (1722)

Books on methodology appear to have been a popular choice for philosophers wanting to make their fortune. We have already seen Wolff's Leibnizian take on the topic and also Lange's more Cartesian version. My previous encounter with Andreas Rüdiger and his rather outdated book on physics, with a quaint notion of air, aether and spirit as the fundamental elements, didn't make me expect much. I was pleasantly surprised to find that Rudiger had some intruiging novelties in store with his approach to methodology.

Although Rüdiger's two books have markedly different topics, they both share common enemies. Rudiger's philosophy is clearly anti-Aristotelian, which wasn't strange at the beginning of 18^th century. What is more, it is also anti-Cartesian. The best indication of this in methodology is Rüdiger's denial of any inherent or inborn ideas. Rüdiger is clearly inspired by Lockean criticism in this respect – different cultures have different ideas, and thus we can expect none of those ideas to be inborn. Hence, all ideas – and ultimately, all forms of cognition – should be such that they can be reduced to sensations: they should be combinations of sensory ideas, abstractions from them etc.

Rüdiger's Lockean leanings form an interesting contrast with the work of Lange, the other thus far met Thomasian. As we have seen, Lange attempted to base a pietist philosophy on the Cartesian fundament of a clear cogito. Rüdiger shies away from all things Cartesian, because Descartes' mechanistic tendencies point almost inevitably towards Spinozan pantheism and perhaps also because it is hard to reconcile Cartesian scientism with a devout religious outlook. English empiricists, on the other hand, were not so clearly scientists, and like Hume would do later for Jacobi, Locke offered Rüdiger a good basis for religious statements.

Rüdiger's Christian tendencies modify Lockean philosophy in an interesting manner. On basis of his physical writings Rüdiger notes that animals in general appear to have inborn ideas – at least they manage to do things instinctually or without any training. Rüdiger concludes then that humans should also by nature have inborn ideas, although experience tells us that they do not. This discrepancy is conveniently explained by the biblical tale of fall: humans were supposed to have inborn ideas, but due to their corrupted state, their connection with these ideas has been sundered.

Another modification of empiricism concerns the clarity of ideas, which in general should on Rüdiger's opinion be based on the connection of the ideas with sensations – the more sensuous content we can give to an idea, the clearer it will be. Such empiricist criterion of clearness is obviously meant to weed out confusing philosophical ideas – if it is not clear, discard it. The only exception is provided by Christian mysteries, such as trinity, because they apparently point out the inevitable finity and imperfection of human cognition – they show boundaries humans at least in the present life cannot break.

The idea of boundaries of human cognition shares some affinities with later Kantian philosophy, and even more similarities with Kant we can see in Rüdiger's ideas on mathematics, which I shall investigate next time.