Some readers might remember that I was rather charmed by Lange's habit of beginning the philosophy of history from biblical times. Well, the same trick does not work as well the second time, hence, I was somewhat dissapointed by the author's insistence that true physics could be found in Genesis and that the further development of philosophy mostly ruined this fabulous start.
The similarity is not accidental, because the obscure author of Physica divina, Andreas Rüdiger, belonged to the same loose circle of philosophers as Lange. Both Rüdiger and Lange were Thomasians, named by their affiliation to Christian Thomasius, first-ever philosopher to write in German. And like Lange, Rüdiger also spent a great deal of his time for criticising Wolff's philosophy, as we shall see in the future.
As the title indicates so well, Rüdiger's book is aimed against both superstition and atheism: superstition divinises the natural world and atheism gets rid of the divine altogether, and the task is to stick with God, but not confuse him with the natural world. True, the book also contains nowadays rather quaint sounding physical theories, which concern all the questions of contemporary natural science – the nature of space, time and motion, movements of planets and stars, basic elements and their combinations, meteorological phenomena, magnetism, plants and animals. But Rüdiger is not satisfied with expounding his own theories, but he also criticises theories of earlier philosophers and shows how his own ideas can help to refute both two extremes.
Most of Rüdiger's enemies are easy to guess: Aristotle and atomists. But the inclusion of Descartes as one of the enemies is somewhat surprising, considering Lange's appreciation of the French philosopher. Yet, Rüdiger's view on Descartes reveals that he understood the implications of Cartesian and generally the modern natural science. In a Cartesian world view, the material things move each other mechanically, through push and pull. The nearest explanation of an event involving material things is another event with other material things. No God is therefore needed, because the eternal movement of matter is enough for explaining the continuance of the movement of matter, and Cartesian physics opens in this way a door to atheism.
Rüdiger's views on Descartes bear a striking resemblance to Jacobi's idea of all modern, mechanistic philosophy leading to atheism, but even more interesting is Rüdiger's idea why Descartes had to fail. The main mistake Descartes made, Rüdiger suggests, is the overt mathematization of physics. Mathematics is a science of possibilities, Rüdiger states. This might be a quip against Wolff, who had stated that philosophy is the science of possibilities. For Rüdiger philosophy is instead the science of what there actually is.
Whereas possibilities meant for Wolff mainly the actual capacities for generating things – real definitions – the possibilities of Rüdiger refer mainly to mere nominal definitions, that is, to mere words which might have no actual reference. In mathematics we can just put together descriptions without any consideration as to whether they describe anything that could be actual. Indeed, mathematics, says Rüdiger, is at least partially false: nowadays we might say that mathematics idealises and hence abstracts from certain characteristics of the actual world. Just because mathematics is an idealised picture of the world, it cannot grasp the true physics.
Rüdiger's idea that mathematics and philosophy are two completely separate disciplines is something that the later German philosophers agreed with: for instance, Hegel made fun of philosophers who tried to use mathematical method, although it was completely unsuitable for philosophical purposes. Interestingly, Kant admits the difference of the two disciplines, but for almost completely opposite reasons than Rüdiger. For Kant, philosophy is the discipline that can only analyse the meanings of concepts, but it cannot construct them – that is, philosophy does not have the means to actualise its concepts, while mathematician can draw his figures at least in pure intuition.
Rüdiger also argues that mathematization of philosophy eventually makes Cartesian proofs for the existence of God futile: Descartes starts by assuming the nominal definition of God, which is completely ineffective in stating anything about what there actually is. Rüdiger's criticism is reminiscent of Kant's later comment that concept of God as such does not involve existence, although ontological proof attempts to deduce one from the other. Rüdiger's further comments that Cartesian mistake is repeated by Spinoza who just assumes the definition of substance as something completely independent of anything else – without noting that such definition might not make sense, because we cannot generate anything corresponding to it: a similar criticism against Spinozan definitions is later voiced by Hegel.
I think that this will suffice for Rüdiger's Physica. Even if I found it philosophically valuable to investigate his theories of air and aether as the basic elements, I would still be in a hurry to move beyond mere physics. That's right, next time I shall begin to do some serious philosophy and tackle the first ever German book on metaphysics.