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 My previous encounter with Andreas Rüdiger and his rather outdated book on physics, with a quaint notion of air, aether and spirit as the fundamental elements, didn't make me expect much.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.