2.3 The scientific revolution

The first work of René Descartes (1596-1650) was in mathematics and science. He is well known for the ‘Cartesian coordinates’ used in drawing graphs in all kinds of mathematical physics. He formulated theories for how the internal organs of animal bodies operate from natural causes. He took these causes as operating according to a mechanical philosophy, where the sizes and shapes of components of systems are what determine their operation.

Later in his life Descartes wanted to make a new foundation for philosophy, in particular one that kept natural science separate from the human souls responsible for rational thought and hence also separate from religion. His philosophy took the (by now well-known) skeptical approach in order to see what can be known when conventional knowledge is not taken for granted. By means of his ‘Cogito, ergo sum’, he concluded that we have a separate ‘rational soul’ by means of which we can have intellectual logic, thought, and comprehension. He contrasted this soul with the extended objects he had used in his mechanical philosophy. He concluded that there exist two types of substances: rational souls which are constituted by thought and physical objects which are constituted by extension. Rational souls are not extended, and physical objects cannot think rationally. All non-rational processes in humans and animals (reflexes, sensations and feelings) are to be entirely explained by the mechanical operation of extended bodies and their parts. As many have pointed out, however, Descartes did not explain the connection between souls and the natural world.^2.3

Descartes was merely formalizing what had already been believed since even before Aquinas: that there was a natural world of causes and effects and, in addition, a set of human souls of some immaterial nature and capable of rational thought. The fact that Descartes brought this distinction clearly into the open has effectively made him a scapegoat for everyone who has complaints about our understanding of mind and its relation to the body. The name ‘Cartesian dualism’ has become a term of derision.^2.4However, Bolton (1999) points out that when we “attribute the influence of Dualism to Descartes, we are implicitly attributing to him the power of imposing his own peculiar way of thinking on a whole civilization for three centuries together. In reality, this kind of power is so rare that it is usually considered an attribute of the founders of religions, not of philosophers.”

In an attempt to unify what Descartes left separate, Baruch Spinoza (1632-1677) concluded that whatever exists must have the properties of both extension and rationality. Furthermore, it is the single God which exists with this combination of attributes, a God which exists impersonally. All of us apparently separate beings are in reality modes of existence of that One God. This again is explicitly a non-dualist and pantheist view of reality and is hence distinct from theism. However, it is a demonstration of what kind of theory might have to be conceived of in order to be logically and philosophically consistent. Spinoza’s work demonstrates again the importance of considering the nature of God if we are to have any satisfactory account also of the physical world.

Isaac Newton (1643-1727) is famous for having developed mathematical treatments for many natural phenomena, especially concerning mechanics, gravity and optics, and he is seen by many today as the prototypical modern scientist. However, he adhered to a very strict monotheism wherein God had absolute Omnipotence. Since this was not orthodox from the Christian point of view--he did not allow that Jesus could be divine--it was hidden from the public even in his own lifetime. Like Nicodemus, he came to God in secret.^2.5Though many today think of Newton as a deist, he in fact followed theism rather diligently. He took God as sometimes directly active in the world in order, for example, to reward moral behavior. Because Newton hid this theism, this aspect of his thinking had little public influence. This split within Newton between theism and naturalism was sustained by the public perception of him as a natural philosopher (physicist). His reluctance to publicly bridge this gap was a precursor to many later divergences within philosophy and science between theories of theism and of nature.

Gottfried Leibniz (1646-1716), a contemporary of and a competitor to Newton, developed metaphysical ideas that had great influence on early scientific Enlightenment but which were less than a full theism. Leibniz viewed God and nature as operating in parallel, with a perfect God creating the best possible universe that functioned perfectly on its own. He had all of nature consisting of atoms or ‘monads’, each of which had some kind of basic mentality and each of which lasted forever. This is a kind of pan-psychism, but the scientific public preserved only the idea that atoms last forever and do so independently of God. There is no room in Leibniz’s system for God to influence the world, and this was one reason for his arguments against the theism of Clarke and Newton, as will be further discussed in Chapter 30. Leibniz may have wanted to preserve some kind of non-denominational theism in the interests of civil liberty and tolerance, but, because he wrote both God and minds out of causal influence on the world, the long-term effect of this writings was to maintain a ‘two kingdoms’ approach to scientific and religious knowledge. In the end this favored naturalism.