Descartes, Spinoza, Malebranche, and Leibniz

God Remains Constant

4.8. The Three Substances: Attributes and Modes

Descartes defines substance as that which does not need anything other than itself to exist. The only being that subsists by itself is God, res infinite. Other beings require creation and preservation by God. While God is the only substance in the truest sense, by analogy, we may also consider created beings who only need God's concurrence to exist as substances. This distinguishes two created substances: the ego or thinking substance (res cogitans) and extended substance or bodies (res extensa). We have clear and distinct ideas of them: they are autonomous or independent. We know substances by their attributes. Descartes also speaks of modes, which are variable modifications of the substance and need it to exist. Figure and movement are modes of extended substance, and imagination and feeling are modes of thinking substance.

4.9. The Man

Man is a composite of two substances: the thinking substance and the extended substance. As the understanding has a clear and distinct idea of each, it is clear that these are two different, independent substances, and that the soul can exist without the body; the body's death is not the soul's death. This anthropological dualism has important consequences: firstly, the assertion of the soul's immortality, and secondly, the affirmation of human freedom. The soul is excluded from the mechanism and necessity typical of bodies (extended substance). Man is free, but freedom is not identified with indifference. On the contrary, the less free will is, the more indifferent it is to choose between one thing and another. However, it is free when, having the understanding of clear and distinct ideas about good or truth, the will is inclined towards it and chooses it. Moreover, the choice proposed by the understanding expresses the central idea of Descartes' ethics.

Other Rationalist Ideas

5.1. Baruch Spinoza (1632-1677)

Spinoza understands substance as that which exists by itself and does not need the concept of another thing to be formed. Such conditions can only be fulfilled by God: He is the only substance that exists and is identified with Nature: monism and pantheism. The attributes of God are what the intellect perceives as constituting the substance: they are infinite, but we know only two: res extensa and res cogitans, which are no longer two substances but two manifestations of it. Modes are variations of the substance, so they cannot be conceived without it. Therefore, all beings that exist are nothing but varieties of divinity. Man is a composite of two modes of the attributes of the divine substance: only from this comes the drive. The soul is only an idea of the body and disappears when the body dies; it is not immortal. The problem of mind-body interaction, and others that could generate Cartesian dualism, cease to exist with Spinoza. There is only one substance, God, the source of everything, and that is displayed in the things that exist, which are his modes.

5.2. Nicolas Malebranche

Malebranche is the greatest representative of occasionalism in the 17th century. The only being with real causal efficacy is God; creatures are but occasions that God uses in order to fulfill his designs. There is no necessary causal relationship from one body to another or from one spirit to another. From this perspective, the problem of mind-matter interaction among creatures is nullified: God is the only being with causal efficacy. He also defends the ontological view that man knows all things in God. Since the object of knowledge are ideas, not things, and those entities are well above those things, they are not produced by them. And since only God, as the creator of all, has in mind the archetypes of things, and since God is present in the soul of man, we view the ideas in God. Here, the Augustinian theory of illumination is mixed with the Cartesian view of God as creator and guarantor of truth.

5.3. G. Wilhelm Leibniz

He tried to overcome the empiricism of Locke. Empiricism had endorsed, in a peculiar way, the old aphorism that "nothing is in the intellect that was not previously in the senses"; to that, Leibniz...