Problems for Aristotelianism

Last time, we saw how medieval thinkers, such as Thomas Aquinas, thought of bodies in terms of matter and form. This model of analysis, in terms of matter and form, dominated the medieval university since roughly 1200 onward. But in the 17th century, it came under attack from thinkers such as Rene Descartes and Robert Boyle. And that raises two questions. First, why did it come under attack? And second, what did Boyle and Descartes put in its place? It’s to these questions that we’ll turn in this video. As for the first question, the main target of the early modern critique of scholastic natural philosophy was the notion of substantial form.

As we saw last time, the substantial form of a body was a principle that made it the kind of body that it was, and which made it move and behave in certain ways. Thus, water was water in this account as a result of its substantial form. And it was as a result of the substantial form that water would boil when heated and cool down again after the source of heat was removed. But simple as this may sound, Descartes found it hard to see what these substantial forms could possibly be. Indeed, even many scholastics had admitted that, all by themselves, substantial forms could not be seen or otherwise observed.

In the 16th century, the Spanish Jesuit Francisco Suarez tried to shed light on this situation by comparing substantial forms to human souls. Just as a human body has a soul that steers it from the inside, he argued, other materials, too, have a substantial form that, as it were, guides their behaviour and motions from within. But according to Descartes this only made the notion of substantial form more problematic than it already was, because if substantial forms were indeed like souls, then this only went to show that the scholastics conceived of nature in a far too anthropomorphic way by putting soul-like principles even in inanimate materials, such as water.

According to Descartes, the ingredients of all bodies are minute particles of matter, or corpuscles. These corpuscles lack any kind of an engine and all by themselves are purely passive. They only move as a result of collision with another particle, and the way in which that move is determined by a few simple laws of motion. As a result of this law-guided motion, some particles will stick together and form stable complex structures. These stable complex structures are the bodies that we see around us. This idea is known as corpuscularianism. And in Descartes, it combined with another idea, according to which the physical properties of bodies are the result of the inner configuration of their particles.

Thus, a body looks the way it does because of the way in which its particles are arranged, and it moves and behaves the way it does because of the mechanical interaction between its particles. This idea is known as mechanism. This combination of corpuscularianism and mechanism, as it were, exorcised the soul-like forms of the scholastics. The formation of bodies was the result of the law-guided motion of particles. And thus in the case of clocks and watches, the behaviour and motion of bodies was the result of the mechanical interaction between their material parts.

Formulations of this mechanical worldview can be found not only in Descartes, but also by people like the chemist Robert Boyle and the other early members of the so-called Royal Society for the Improvement of Natural Knowledge, which was founded in 1660. In the eyes of many people, this combination of corpuscularianism and mechanism provided a much more intelligible, and certainly less anthropomorphic, kind of nature than scholastic Aristoteliansm had. Even so, the new model also came with problems of its own. And it is to some of these problems that we’ll turn in the next video.