We could say that Neoplatonists like Proclus and Simplicius with their studies of Plato and Aristotle were the latest possible point at which the use of commentary as a philosophical tool was introduced. During the Middle Ages the success of commentaries was obvious and one could even say that the modern indiscriminate use of references in articles resembles a form of commentary.
We have already seen a philosophical commentary, in which Lange presented a number of passages ripped out of their context from Wolff's writings and then criticized what he thought was meant in those passages. A more faithful reading of Wolff is presented by Andreas Rüdiger, a follower of Christian Thomasius we have met a few times before, in his work Herrn Christian Wolffens Meinung von dem Wesen der Seele und eines Geistes überhaupt: und D. Andreas Rüdigers Gegen-Meinung. Rüdiger gives his reader not just isolated passages, but a whole text of Wolff's rational psychology from the German metaphysics, and leaves his own opinions to a preface and footnotes.
As the name of the work belies, Rüdiger belongs to Wolff's critics, not to his followers. Some of what Rüdiger has to say is clearly based on confusions already dealt by Wolff. For instance, when Rüdiger complains that regarding soul as consisting of a mere force of representing the world would deprive it of all the complexity of its characteristics, such as freedom of its will, we could just point out to Wolff's answer that the force of representation is not meant to be all of what soul is, but only a convenient point from which to deduce all the characteristics of soul.
This does not mean that Rüdiger's criticism is wholly based on confusion. For instance, Rüdiger asks how Wolff can suppose there's an essential difference between souls of humans and of animals, when the difference is based on nothing more than the degree of clarity in their representations. Indeed, he continues, we cannot even say in earnest that animals have less clear experience of things, when their sensory apparatus is sometimes far subtler than ours.
What is probably the most crucial point is the already discussed uneasy synthesis of the notions of the pre-established harmony and the freedom of will. The pre-established harmony is explained by pointing out that even two clocks can show same time without any causal interference, but the problem is how a free agent and a deterministic mechanism could follow the exactly same course of actions. Yes, neither of these series is necessary, but still in one series the later events are determined by the previous events. The problem is exaggerated by Wolff's suggestion that in soul all events are grounded on previous events, just like in the material world: how could one not think of Wolffian soul as a sort of automaton after this?
The problem lies, as Rüdiger points out, in Wolff's notion of ground that combines quite distinct types of relations. Material causes are grounds, but so are human motives (Rüdiger adds animal movements as a group distinct from these two). True, causes and motives do share some characteristics, but they appear to have also crucial differences: cause produces always certain effect necessarily, while motive requires still the will of a person to become reality, that is, while there is not motiveless action, motive does not necessarily lead to action. This distinction is one that Wolff himself noted and he has made it quite clear that he believes in human freedom in choosing what motive to follow. Furthermore, his willingness to distance himself from the pre-established harmony might show a certain skepticism of this theory.
What is remarkable in Rüdiger's book is his willingness to actually suggest an alternative solution to the problem of soul/body-interaction, while earlier critics had just expressed their faith on the possibility of said interaction. Rüdiger notes, firstly, that the matter/soul-distinction can be understood in two separate ways. Firstly, there is the Aristotelian distinction between matter and form, where soul is stated to be one type of form. Aristotelian matter, Rüdiger says, means just substrate (that which is) of a form, which then is the force or activity of the matter (what it does) – thus, form or soul of a living thing consists just of living and its other essential activities. Clearly, such a soul cannot exist without corresponding matter or substrate, and the distinction is more conceptual than ontological.
Still, this does not mean that we could not separate an independent spiritual substance from an independent material substance, and this is what e.g. Descartes did – there is an entity, Descartes said, that is conscious of itself and its own body and various other things, but is still separable from the spatial body. What Rüdiger finds troubling is the identification of spatiality as the distinct characteristic of material substances. Instead, he claims that all created substances must occupy space – and this he thinks is the key to the problem of soul/body-interaction. Soul is not antispatial, but occupies space and even has extension, even if it doesn't act like material substance and exclude other entities from a certain place: thus, a body and a soul can share the same space and also interact with one another, even if this interaction is not like interaction of material substances. What Rüdiger has in mind is then a sort of astral body floating around the crass physical body, and soul is then identified either with this more spiritual body, or in the Aristotelian manner, with its activities.
This seems like a good place to turn to consider Rüdiger's philosophy in general, as the book here will be his last seen in this blog. Of all the philosophers considered thus far, I think I have done least justice to Rüdiger. Partially this has been caused by difficulties in tracking down his works, but most of the blame must be put on my original inability to recognize his independence of the more pietist side of Thomasian legacy, embodied in Lange.
Sure, Rüdiger does have his antiscientist streak, evident best in his vitalistic physics, which cannot but feel quaint nowadays – just look at his theory of soul. Then again, even here Rüdiger is just part of general progression, following Paracelcian influences inherent in German thought and anticipating ideas of Schellingian philosophy of nature. Furthermore, Rüdiger is not speaking from the standpoint of a mystic, but of a practicing doctor, with considerable empirical information.
Still, the most lasting legacy of Rüdiger lies in his methodological considerations on the differences of mathematical and philosophical thinking and on his criticism of Wolffian notion of ground. Both topics were later on picked up by Kant, and the connection is probably not just accidental. Kant has in both cases been influenced by Crucius who had been taught by a person called Hoffman, who was a follower of Rüdiger. I shall see in a couple of years whether Hoffman considered these topics, but for now, I shall leave this school of philosophy and start to consider eloquence.