Substance in Early Modernism: Three Schools of Thought
- Pierce Kozlowski
- Mar 5, 2024
- 9 min read
Updated: Mar 13, 2024
1. Descartes: Substance Dualism
The rationalists of the Early Modern period often tried to reformulate their conceptions of substance in light of new scientific developments. René Descartes undertook that feat by attempting to reformulate the theory of the mind and body, called “substance dualism.” Essentially, Descartes conceived of two primary substances, the first was the mind, and the second was the body. As an aside, Descartes considered God to be a third substance and could be called a “substance triadist,” but for brevity’s sake, the discussion will be abbreviated to account only for his “dualism.”
Descartes’s model of the mind was that it was purely mental and immaterial with no dimensions, so it’s non-spatial and imperceptible (1). It’s also active since it can move itself by its thoughts, but it “can’t be divided” into smaller parts (2). This is the intellectual realm. For Descartes’s model of the body, he says: “whatever has a definite shape and position, and can occupy a region of space . . . it can be perceived by touch, sight, hearing, taste or smell, and can be moved” (3). Descartes agrees with Galileo that the body is “matter and motion,” that it’s extended and spatial, sensibly perceptible, passive compared to the mind, and moveable even though it cannot move itself, contra Aristotle. This is the physical realm. Since the mind and body are so different, they’re distinct substances because they can be conceived separately.
Descartes thought human perceptions occurred in the mind because the intellectual realm was actively perceiving the external world. This interaction between the body and mind is caused by their “union” (4). The body communicates sensory data for the mind (5), with the pinneal gland as the interaction point between the two. The mind then wills and moves the body, with both having opposing characteristics and creating a real dualistic distinction between the intellectual and the physical. The objection to this came from Princess Elisabeth when she asked how an invisible mind can interact with an extended body so as to cause movement, especially when the mind and body are different (6). Descartes reiterated his original point despite conceding the two are often conceived as separate. Elisabeth replied saying the senses only reveal the interaction, not the inner workings, and proposed an extended soul, suggesting Descartes violated his truth principle by forming an uncertain judgment (7).
2. Spinoza: Substance Monism
Holland was known for its tolerance, where Descartes penned his major works. The same was true Baruch Spinoza (1632–1677), who reworked parts of Descartes’s philosophy as a proposal to contentions like those of Princess Elisabeth’s mind-body problem. Spinoza conceived of a single substance rather than two, making him a “substance monist.” Substance in Greek means underlying – for Spinoza, it’s not dependent on anything else, but everything is dependent upon it. Spinoza proceeds deductively. It’s self-caused since substance has no conceptual dependency on anything apart from itself. It necessarily exists since it’s not contingent on any other medium. It’s infinite and eternal since finitude implies dependency, but substance is not dependent. It has an infinite number of properties since every substance is infinite. And lastly, since there cannot be several infinities, there’s only one infinite substance that is altogether eternal, necessary, and independent, whereby everything is an expression of that substance in the form of attributable and modal properties (8). He takes this to imply “substance monism” because there cannot be other substances other than the one, and this is God.
Spinoza’s substance is a stable medium that expresses itself through two categorical properties called “attributes” or “modes.” This is “Dual-Aspect Theory,” where there’s two aspects of the one substance. Attributes are unchanging properties that constitute the essential qualities of the infinite substance, which modes are dependent upon (9). Attributes are the intermediary between substance and modes, and the only known attributes are “thought” and “extension.” The attribute of thought is the intellectual realm of ideas. The attribute of extension is the physical realm of the external world, where Spinoza offers a mechanistic account of creation in an attempt to rid philosophy of applying teleology to extended things, like Descartes. Modes, however, are properties that change over time and constitute the accidental qualities of the infinite substance (10). They are dependent upon (or properties of) attributes, and there are only two known modes called “minds” and “bodies.” Minds relate to the attribute of thought in the intellectual realm; bodies relate to the attribute of extension in the physical realm.
Concerning the mind-body distinction, they are properties of the divine substance. Individuals are modal expressions: their minds depend upon God’s attribute of thought; their body depends upon God’s attribute of extension. Concerning Princess Elisabeth’s mind-body objection, Spinoza does away with Descartes’s position that the mind and body are united. The body seems to perceive sensible data which become perceptions in the mind, and concurrently, the mind seems to control the body – creating a bi-directional interaction. However, the mind and body don’t interact. Rather, they’ve been preprogrammed to appear like they do, implying both realms are isomorphic. Spinoza says, “the order and connection of ideas is the same as the order and connection of things.” And he immediately subjoins: “a mode of extension and the idea of that mode are one and the same, but expressed in two ways” (11). Mental and physical events run parallel to one another without direct interaction. This is “Parallelism,” contrary to Descartes’s interactionism. While there’s a correlational relationship between mind and body, it’s not causal – it’s illusory.
Spinoza also reject’s the Descartes’s libertarian claim that human beings have free will. “In the mind,” he says, “there is no absolute (that is, free) will; rather, the mind is caused to will this or that” (12). Contrary to Hobbes and the Reformers, he’s a soft determinist or “compatibilist.” Spinoza believes human action is mechanistically determined in advance, but maintains that individuals are still morally responsible, and he redefines human freedom to accommodate this. Instead of being absolutely free like God, individuals exercise freedom only when they attain “adequate” knowledge that is clear and distinct (13). Under the attribute of extension, bodies are causally determined; under the attribute of thought, minds are also causally determined, notwithstanding, they enjoy freedom which is rooted in the sole activity of understanding rather than total, spontaneous freedom of the will.
3. Leibniz: Substance Pluralism
Contrary to “dualism” and “monism,” Gottfried Leibniz offered a third possibility. Leibniz contends there’s an infinite number of substances which fall inside two categories – “God” and “monads.” God is the only infinite substance whereas monads are finite ones. Consequently, God is the only non-monad, making everything outside of God a monad. This is called “Substance Pluralism.” For Leibniz, God as substance is omniscient and perfect (14). He clearly and distinctly perceives everything, he’s not constituted of matter, and he’s detached from all bodies (15). Overall, God is he who perceives and causes all that happens inside the universe and is intertwined with it, not simply as an isolated being outside it. Leibniz says, “God is all in all, and is intimately united to all creatures in proportion to how perfect they are.” To this he attaches: “he alone by his influence determines them from outside” (16). Contra Spinoza, Leibniz took pantheism to be a mere metaphor and rejected his non-anthropomorphism, and he rejected Descartes’s abstract conception of God too, since Leibniz thought neither Descartes nor Spinoza accounted for God’s divine justice. Naturally, he emphasized God’s benevolence to better address the problem of evil by reviving the idea of teleology in the material world.
That said, monads are uniquely individual, indivisible, and “simple” entities which are infinite in quantity but finite in quality. Similar to Spinoza’s pantheism, monads are a mirror of God and reality. Leibniz says, “Each substance is like a whole world, and like a mirror of God, or indeed of the whole universe” (17). Each monad is an expression of the entire universe, and contains in itself every event and idea from the past, present, and future. This only occurs from a monad’s own perspective, and many of the ideas it contains are confused and obscure, whereas the ideas of its own perspective are clear and distinct (18). He takes this to mean that all ideas are innate, marking his radical rationalism.
There are both material and immaterial monads. Material monads are infinitely divisible and small, and they’re conscious beings with confused and obscure consciousnesses. Like Conway’s “animism,” Leibniz maintained that all things – even the seemingly inanimate – are conscious. Immaterial monads, are soulful, thinking things, and “windowless” consciousness which can disconnect from bodies and matter (19), and enter a slumberous state where ideas become obscure and confused. These slumberous monads can be awoken by being reincarnated or attached to another material monad which occurs when two biological monads reproduce, with the caveat being that–that person still receives a rational soul that is created and uniquely theirs. Leibniz connects these two concepts by saying that every material monad is synced to an immaterial monad. So for biological monads, they are synced to intellectual monads that have existed since time immemorial, despite having a unique soul.
A famous contention for Leibniz was “occasionalism,” which advocated that God moves back and forth between interacting individuals as their cause. Leibniz found this to be inelegant. Instead, he advocated something identical to Spinoza’s “Parallelism” called the “hypothesis of concomitance,” where God – due to his omniscience – preprogrammed monads in a parallel manner so bodies only appear to interact with one another. Hence, physical events “correspond” to an individual’s idea of them, discarding any notion of a causal interaction between minds and bodies (20). While God’s omniscience yields predetermined programming, Leibniz held the “compatibilist” view that individuals are morally responsible and still retain certain freedom. Understanding this relies on understanding Leibniz’s two principles. First, the “Principle of Non–Contradiction” dictates what’s absolutely necessary, which God and monads must follow since it cannot be otherwise; secondly, the “Principle of Sufficient Reason” dictates what’s contingently necessary, which permits God and monads to do one thing over another since it’s not absolutely necessary (21). Monads are predetermined by absolute necessity since God cannot contradict his omniscience. However, monads still retain a certain free will as a contingent necessity. This affords individual monads to choose their own essence and act according to their nature. This freedom is similar to Spinoza’s compatibilism.
Final Verdict: Conclusion
Leibniz’s theory possessed the greatest strength. First, the explanatory breadth is close between Spinoza and Leibniz. Starting from skepticism, Descartes attempted to solve the mind-body problem via the pinneal gland, while Spinoza and Leibniz rejected skepticism but tackled the same problem via parrallelism. Leibniz, however, also attempted to explain the harmony of the universe, the nature of perception, and to reconcile teleology with mechanisms, potentially giving him an advantage in breadth. Second, the explanatory specificity is, again, close between Spinoza and Leibniz. Descartes tried to explain the mind-body as two substances with the pineal gland as the interaction point while Spinoza embarked on the same assignment, but he included an impressively particular and highly detailed account of God & Nature while rejecting dualism. Leibniz advocates an arguably more complicated account of his monadology, but Spinoza’s specificity and completeness excels, leaving little room for obscurity.
Third, Descartes prevails in simplicity. While Leibniz and Spinoza were attempting to accomplish more, Spinoza’s theory had excessive intricacies on properties which described simple monism. Leibniz, despite being complicated, lacks the complex oddities of Spinoza while his simple monads as foundational building blocks help navigate his ontology. Descartes was commonsensical, presenting his theory with colorful language and vivid analogies while only focusing on the existence and simple nature of the mind and body, giving him an advantage. Lastly, Leibniz was the most conservative. Spinoza’s pantheism, definition of freedom, and cumbersome writing style are as unusual as they are unnatural. Descartes, being the best writer, would be closest had he not made skepticism the litmus test of knowledge – a fundamental disagreement even Leibniz and Spinoza shared, and which is unnatural to most since it’s not a common habit to thoroughly distrust the senses. Leibniz maintained continuity with previous traditions like scholasticism while introducing innovative designs, expressing a balanced approach that uses new ideas atop existing structures. Thus, Leibniz emerges as the strongest overall for these reasons, offering a coherent and comprehensive account of reality.
-By Pierce K. Kozlowski
Footnotes:
René Descartes, “Fourth Meditation,” in Meditations on First Philosophy in Which Are Demonstrated the Existence of God and the Distinction between the Human Soul and Body, ed. and trans. Jonathan Bennet (earlymoderntexts.com, 2007), 17–18, https://www.earlymoderntexts.com/assets/pdfs/descartes1641.pdf.
Descartes, “Sixth Meditation,” 33.
Descartes. “Second Meditation,” 5.
Descartes, 31.
Descartes, 32.
Princess Elisabeth, Letters Written in 1643 to 1664, ed. and trans. Jonathan Bennett (earlymoderntexts.com, 2009), 1, https://www.earlymoderntexts.com/assets/pdfs/descartes1643_1.pdf.
Princess Elisabeth, 7.
Benedict Spinoza, “Part I: God,” in Ethics, ed. and trans. Jonathan Bennett (earlymoderntext.com, 2004), 3–6, https://www.earlymoderntexts.com/assets/pdfs/spinoza1665.pdf.
Spinoza, 1.
Ibid.
Spinoza, “Part II: The Mind,” 25–26.
Spinoza, 44–45.
Spinoza, “Part III: The Origin and Nature of the Affects,” 51.
Gottfried Leibniz, “Sections 1–13,” in Discourse on Metaphysics, ed. and trans. Jonathan Bennett (earlymoderntext.com, 2007), 1, https://www.earlymoderntexts.com/assets/pdfs/leibniz1686d.pdf
Leibniz, The Principles of Philosophy known as Monadology, (earlymoderntext.com, 2004), 10, https://www.earlymoderntexts.com/assets/pdfs/leibniz1714b.pdf
Leibniz, “Sections 24–37,” in Discourse on Metaphysics, 22.
Leibniz, “Sections 1–13,” 5.
Ibid.
Leibniz, The Principles of Philosophy known as Monadology, 2.
Leibniz, 4–5.
Leibniz, 5.
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