Descartes, Leibniz and Spinoza on Substance
Descartes, Spinoza and Leibniz are the three philosophers that stand out among their contemporaries in the seventeenth century as the greatest rationalists. While constructing their philosophical systems, each of them sought to incorporate philosophical and theological foundations to explain the existence and the essence of substance as regards, mental, physical and moral universe. In discussing their philosophy in relation to substance, the three philosophers are known in their philosophical systems as Leibnizian pluralism, Spinozan monism and Cartesian dualism.
Descartes’ Account on Substance: Cartesian Duality
Descartes’ philosophical system on substance was extremely influential on the subsequent 17 century philosophers who developed their own accounts in reference to his philosophy. While defining substance, Descartes has rendered two accounts. In the “Third meditation”, he defined substance in terms of independence. He observed that there were two kinds of substances: the Substance and the created substance. In this regard, the former refers to the subject that is “infinite, eternal, immutable, independent, supremely intelligent, supremely powerful, creator of all things” – God. The latter refers to an entity that is a “limited being, without infinite formal reality whose existence only depends on the active powers of God”. However, to speak strictly philosophically, there can only be one substance- the Substance or God. In this case, God is the only substance which does not depend on the existence of other beings, as He is a superior body, “which contains the reality of all creatures in higher forms (eminently)”. In some cases Descartes tends to ignore the differences between God and the creation. He adopts the traditional way of defining a substance by claiming that a substance is any subject that bears modes in itself, but is not a mode of any subject. In this regards, attributes that a substance constitutes will reveal its nature and essence, and they will \dictate its properties. However, Descartes notes that thoughts/ rational minds and extension/matter are the kinds of attributes that characterizes an individual. By matter he meant that a substance could have volume by depicting depth, breadth and length. By thoughts he meant that a substance could have rational minds. For his philosophy, an embodied man will fit in his system by the fact he has mind and the body. Further he noted that God was the only one who was subjectively independent. Although he created other substances they are subjectively dependent and causally from God. Therefore, at the end Descartes seems committed to his dualism by concluding that there are two kinds of substances: thinking substances (God and souls) and material substances (physical bodies).
Spinoza’s Account on Substance- Spinozan Monism
It is important to note that at the time when Spinoza was constructing his philosophical system, Descartes’ work had been read widely. In fact, in his definition of the substance he follows the Descartes paradigm of selfhood; he defines substance as an entity that understands itself or is conceived through itself. For Spinoza however, he thinks that there can only be one unique substance that bears particular attributes. He has also reiterated that the substance is indivisible. Therefore for Spinoza’s philosophical construct, only one substance exists: God as one thinking substance, material or extended substance, and one who has all other attributes, or if any. Therefore from his viewpoint, all substances are identical and are in unity. Otherwise there exists only one substances- God, who is both material and thinking. He illustrates this point by noting that since God “is the efficient cause (generates all its effects) of all things”, “nothing can exist outside God by which he is determined”. In fact he concludes this point by noting that everything is "caused by," "determined by," or "necessarily follows from" God, or, God is the cause of both the essence and existence of things.
Leibniz’s Account on Substance- Leibnizan Pluralism
Leibniz views were influenced by philosophies of both Descartes and Spinoza. Like Descartes, Leibniz puts it that God is the only substance which is absolutely perfect and independent. He also notes that substances have to consist of attributes and modes. He infers that substances are unities and are active in that apart from being efficacious they were ultimately created for their own actions. However, he believes that their efficacious actions cannot extend to other substances- “Monads cannot act on each other causally they can be aligned with each other”. Leibniz notes that simple substances or monads are minds and souls. In this regard, since substances cannot be divided into parts, there are no extended substances and all substance, God included, are the same. However, Leibniz agrees that although God is a substance, he is necessary for the creation of other substances. His commitment to defend his pluralist idealism comes in the La Monadologie when he states that monads which are ultimately spiritual in essence are immortal and posses internal differences that can only be determined spiritually. These monads are many and they are represented by centers of forces in the universe.
Agreements among the Three Accounts
The three accounts accept the notion that God is the creator and can be the destroyer of other subjects. Moreover, they all accept that atoms, since they do not have minds or souls cannot be substances. The three explain substance in terms of matter and mind. In all cases the philosophers seem to be working towards describing substances as ultimate subjects. They are all confirming God’s infinite and independent existence; other subjects that seem to have finite existence are dependent on Him. Nonetheless, they agree that a substance must bear certain properties or modes that differentiate it from others.
Comparing and Contrasting Descartes and Spinoza
As already noted Spinoza’s thoughts were heavily influenced with Cartesian philosophies. Just like Descartes, he defines substance on the perspective of selfhood. They also agree that God exist and he is a substance who is independent and finite. According to them, too, God has infinite causal capabilities on created subjects.
However, divergence between them results when Spinoza rejects the Cartesian duality of substances into infinite and finite thinking substances. For Spinoza, there is only one thinking substance, which is God or nature and is causal to what Descartes refers to as finite substances. Further he rejects the Descartes’ division of substances into thinking substances and extended/ material substances. For Spinoza, there is one type of substance – the infinite substance or put it simply as Substance. In all of Spinoza’s argument, it is notable that although there is only one substance, it is neither mind nor the body. Further, despite agreeing with Descartes that Substance has an essence in which it can be conceived, he asserts that it is an infinite essence. In this regard, it can be conceived of as material/extended or as thinking. However, theologically in their thinking, as Descartes identified God with Christianity, Spinoza identified Him with natural world in which all human beings live.
Comparing and Contrasting Descartes and Leibniz
It is important to note that historically, Leibniz constructed his philosophical systems on Monadology after he had read works of both Descartes and Spinoza. Like Descartes, Leibniz contented that the only subject that can absolutely be independent and perfect is God. Secondly he agrees with him that a substance must bear certain properties or modes. In this regard therefore he writes that when several modes are attributed to a certain subject without being attributed to any other, then it will be called a substance. He also contents that God is the only infinite substance that creates and determines the course of the universe. However, taking into account that both men were Christians, it is possible that they would have been influenced by the allusion of the omnipresent and perfect existence of a Christian God. Unlike Spinoza’s account, their demonstrations of substance seem very much Theo-centric. This case is nevertheless very different for some of the contemporary philosophers who do not believe in the existence of God, and hence in his regard as a substance.
At the point of deviation, although the two men agree that God is an infinite substance, and conserves the finite world, they disagree on what fundamentally constitutes the world. While Descartes notes that there are only two kinds of substances, thinking and material/ extended substances, Leibniz notes that there are no extended substances. Leibniz illustrates that created or extended substances are much like thinking substances. Committed to differ with Descartes with his duality, he notes that substances are simple and are just minds and souls. While Spinoza and Descartes have rendered their accounts putting into consideration matter and mind, Leibniz has introduced force which will ultimately determine where a substance is located. According to him, a substance is every centre of force in the universe. They are these centers of forces that he calls monads. The monads or substances are immortal and they are only determined by their spiritual character(s).
Comparing and Contrasting Spinoza and Leibniz
