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.