Spinoza and Aquinas on the Divine Substance

In this article, two views concerning the nature of the Divine Substance will be explained and compared. First, some key points concerning Benedict (Baruch) Spinoza’s view will be given. After that, the classical view of God will be offered. As the classical view is explained, similarities and differences between the two views will be highlighted.

Benedict (Baruch) Spinoza’s View of Divine Substance

Substance as Self-Sufficient

In his book A Study of Spinoza’s Ethics, Jonathan Bennett outlines five aspects of Spinoza’s thinking that set the stage for his philosophy in general and his view of the Divine Substance in particular. Two of those five aspects will be mentioned here, as they are more pertinent to our discussion of the Divine Substance. The two aspects of his thinking which are relevant to our discussion are his implicit notions of “explanatory rationalism” and “causal rationalism”. Explanatory rationalism refers to the idea that, given a fact, an explanation may be given for that fact. Causal rationalism is an extension of explanatory rationalism. It makes causal relationships strong analogs to logical relationships.

According to Bennett, explanatory rationalism “is the refusal to admit brute facts”. In other words, the explanatory rationalist cannot offer ‘it just is the case’ as an explanation for any given fact. Everything, in principle, must be explainable. Causal rationalism is the refusal to allow a distinction between what is logically necessary and what is causally necessary. The causal rationalist thinks that logical necessity does not merely entail causal necessity; rather, to speak of logical necessity is simply another way of talking about causal necessity. As Bennett states, “When [Spinoza] speaks of ‘the reason or cause why Nature acts’… he thinks he is talking about one relation, not two.”

A serious problem naturally arises from explanatory and causal rationalism. They inevitably lead to an infinite regress of explanations and causes. For example, to explain “F” Spinoza points to “E” as the cause of “F”. However, “E” must be explained as well since everything must have an explanation. In order to explain “E” Spinoza points to “D” as the cause of “E”. Unless Spinoza can offer a stopping point for his explanations, he will inevitably end up in some kind of infinite regress of causes / explanations. Whether this regress is really vicious or not is beyond the scope of this article. The point here is that Spinoza looks to substance as the ultimate explanation / cause of everything.

However, to be consistent, Spinoza needs to answer the following question: How can substance be the ultimate explanatory stopping point given the fact that explanatory rationalism demands an explanation for everything? The answer lies in rationalist’s notion of substance. For the rationalists in general, substance was thought to be that which is causally self-sufficient.

However, to be self-sufficient appears to admit of a brute fact, which violates Spinoza’s underlying form of rationalism. Spinoza resolves this problem with proposition 7 which states, “It pertains to the nature of substance to exist.” Thus, substance can be the cause of itself and the cause of everything else because it is “of the nature” of substance to exist. To Spinoza, this is an explanation for the existence of substance.

God is Substance

Spinoza defines substance as “that which is in itself and is conceived through itself”. Understanding the phrase “in itself” is very important for understanding Spinoza’s view of substance. According to Aristotle, a substance is that aspect of being which undergoes change. It is the enduring thing in which accidents inhere. Accidents do not exist in their own right, but exist only in substances. Upon considering the distinction between substance and accidents, Spinoza wondered how any finite substance could exist in itself since finite substances are always found within something else. Accidents like “pale” and “short” may inhere in a finite “human substance”, but human beings are finite creatures that find themselves in the greater context of the universe. Spinoza suspected that the traditional distinction between substance and accidents in finite things was misguided.

If an accident is an accident because it does not exist in itself but rather it exists in another, then the following question may be asked concerning “finite substances”. Since human beings themselves exist in the universe, why should they not be considered accidents?

Furthermore, if accidents are modifications of a substance, why not think of finite substances as mere modifications of that which really endures change without itself changing: namely, the universe as a whole? Hence Spinoza moves away from Aristotle’s accidents and clings to the view that finite things are modes of a single substance. Given a mechanistic view of the universe, this notion makes sense. If anything deserves the title “substance”, it would be the universe itself because everything in it changes, while it remains the universe.

At this point, it might be tempting to stop here and say that Spinoza simply takes the sum of the modes in the universe and then affixes the label substance on that sum. However, this would be a misrepresentation of his view. In his book The Philosophy of Spinoza, Harry Austryn Wolfson says that Spinoza “[declares] that substance is a whole which exists over and above and beyond the sum of the modes”. If Wolfson is correct, then substance cannot be reduced to the world, nor can substance be identical with it. Thus, the question still stands: What is substance? For Spinoza, God is Substance. In the Ethics, God is defined in the following way: “By God, I understand Being absolutely infinite, that is to say, substance consisting of infinite attributes, each one of which expresses eternal and infinite essence.”

In identifying God as Substance, Spinoza is not necessarily saying that the universe is God or that the universe is an absolutely infinite Being whose essence is expressed in each of its attributes. Rather, God is more than the universe. The universe is in God in the strongest possible sense, but only two of God’s attributes are expressed in the universe. As Genevieve Lloyd argues in her book Spinoza and the Ethics, God is not reducible to the universe because “no one of his attributes can claim exclusive identification with him”.

So in sum, God is substance and substance is not the universe; however, the universe is in God in the strictest possible sense.

God and His Attributes

To this point, substance and modes have been discussed, but there is another ontological category used by Spinoza which was briefly mentioned above. Contained within his definition of God, he makes a claim concerning God’s attributes. He says that God is substance consisting of infinite attributes. But what exactly does Spinoza mean by attribute? Fortunately, he defines the term for his readers; however, his definition requires some explanation to be understood. He defines an attribute as “that which the intellect perceives of substance, as if constituting its essence”. To better grasp what he means by attribute, it will be helpful to briefly revisit the terms substance and modes again.

When speaking of substance Spinoza speaks of a thing. When speaking of modes, Spinoza speaks of modifications made to that thing. Or again, when speaking of a substance, Spinoza is talking about the subject of predication. When he speaks of modes, he is talking about predications made of the subject. For example, if a human being could be a substance, then the different properties of a human would be the modes of that person. The person taken as a basic unit would be the substance and the person’s eye color, hair, height, etc. would be the various modes of that person. In the case of Spinoza, God is Substance and everything we see in the world is a mode of that substance.

Where then are attributes to be found in this ontology? They are to be found at the most fundamental level of our understanding of the world. This is because attributes are the most basic modes of being. All particular modes in the world are reducible to one of two irreducibly basic categories: thought or extension. Every declarative statement we make is either predicating a mode of thought or a mode of extension of a subject. Thus, attributes are those basic non-substantial categories through which finite modes are conceived. Since they are the most basic categories, one attribute may not be conceived through another attribute. An attribute may only be conceived through itself.

As has been stated above, God has an infinite number of attributes, only two of which are known to us. Our intellect perceives God through thought and extension as if each of those distinct attributes constituted the essence of God. At first glance, this appears to be a very odd proposition. If God has an infinite number of attributes, then how can the mind perceived God’s essence through a single attribute? The answer lies in how Spinoza relates attributes in the Divine Substance. According to Spinoza, one should not think of the attributes of God as discrete parts in God. God is not a collection or aggregation of attributes; instead, He is an absolute unity of His attributes. Thus, because of the absolute unity of God’s attributes, to know one attribute is to have knowledge of the essence of God.

Only One Substance

One of the most striking features of Spinoza’s philosophy is his strict monism. He does not hold to a Creator / creature distinction. When Spinoza distinguishes between modes, attributes, and substances he is dividing up the aspects of a single Substance. In other words, he thinks that there are an infinite number of modes, and an infinite number of attributes, but he thinks that all of these belong to a single Being whom he called God. In essence, Spinoza thought that God is all there is. The question we now turn to is this: How does Spinoza prove that God is all there is?

Bennett summarizes Spinoza’s argument in the following way:

1. There must be a substance with every possible attribute;

2. There cannot be two substances with an attribute in common;

There cannot be more than one substance.

Premise 1: Why think that there must be a substance with every possible attribute? This premise stands on Spinoza’s proposition that “It pertains to the nature of substance to exist”. In other words, if something is a substance, then it necessarily exists. Spinoza’s concept of a necessary being entails a being with every possible attribute. For he says, “the more reality or being [a being] has, the more attributes it possesses…”. According to Spinoza, God has the most being and reality and must therefore possess infinite attributes. So there must be at least one substance, namely God, with every possible attribute.

Premise 2: Why think that there cannot be two substances with an attribute in common? There cannot be two substances with an attribute in common because a thing may only differ from another thing by a difference in attribute or a difference in affection. But to differ by either one of these is not to differ substantially since attributes are always attributes of a substance and substances are always prior to their affections. If two distinct attributes are known to the intellect, what grounds would the intellect have for arriving at two substances? Spinoza’s answer is that the intellect would not have grounds to deduce two substances from the existence of two distinct attributes. Therefore, Spinoza demands that there is only one substance with many attributes, not multiple substances with multiple attributes.

Conclusion: Given the fact that there is one substance with every attribute, in order for there to be a second substance it would have to share an attribute with the first substance because the first substance has every possible attribute. However, two substances cannot share an attribute because for a thing to differ substantially it must differ substantially. A thing may only be known to differ substantially through its attributes or its affections. But the intellect does not have grounds for claiming a substantial difference between two things that differ by its attributes or its affections. Therefore, there is one Substance which has infinite attributes.

Everything Happens of Necessity

Another prominent feature of Spinoza’s philosophy is his strict determinism. In the Ethics, Spinoza says, “God is the efficient cause of all things which can fall under the infinite intellect”. For Spinoza this means that anything which the Divine Intellect can conceive will happen necessarily. In 1p29, Spinoza says, “In nature there is nothing contingent, but all things are determined from the necessity of the divine nature to exist and act in a certain manner.” This is the strongest possible form of determinism. There is no contingency in the world at all. According to Spinoza, anyone who calls something “contingent” does so because he has a defective knowledge of the world.

In 1p16c2, Spinoza goes on to say that God causes all things through Himself. God does not depend on anything, and as such He is the first cause of everything in the strongest sense possible. This view is the denial that there is a bidirectional causal order between God and the world. Rather, there is a strict causal direction that flows necessarily from the nature of God to all of God’s Divine actions. In fact, while Spinoza claims that God is “free” (based on 1d7), all he means by this is that God is free to be determined by His own nature rather than determined to act by something outside of Himself. God’s nature necessitates every particular divine act.

This notion is fleshed out in 1p33 where he says, “Things could have been produced by God in no other manner and in no other order than that in which they have been produced.” Spinoza demonstrates this by arguing that if the Divine Nature could produce something other than what is now the case, then there would be two Gods. However, in order for there to be two Gods, one God would have to share an attribute with the other God since both have infinite attributes. But this is absurd because there cannot be two or more substances which share the same attribute. Therefore, since there is only one God with infinite attributes, everything is determined of necessity.

Thomas Aquinas’ View of Divine Substance

God as Self-Sufficient

Like Spinoza, Aquinas held that God is self-sufficient. God does not depend on anything for His Being; rather, every finite thing owes its existence to God. Aquinas and Spinoza disagree, however, concerning whether or not God, as a self-sufficient being, is material or immaterial. Spinoza says that God is material, and Aquinas thinks God is immaterial.

For Aquinas, God cannot be self-sufficient if He is a material being because material beings are composed of matter. To be composed of matter is to be in potency since whatever is in matter is in potency. Since to be material is to be in potency, and since there is no potency in God, it follows that there is no matter in God.

In keeping with God as a self-sufficient being, both Aquinas and Spinoza hold that God’s essence somehow involves existence. When the claims of Aquinas and Spinoza are put side by side, they look very similar. For example:

Spinoza: “The existence of God and His essence are one and the same thing.”

Aquinas: “God’s being is His essence.”

Both, in fact, maintain that God exists necessarily and that God’s essence is identical with his existence. Both also think that, as a necessary being, God must be immutable. However, even though they agree that it is of God’s essence to exist, these thinkers come to very different conclusions about God’s nature and His attributes. These differences, in large part, stem from each thinker’s view of substance.

Aquinas on Substance

Unlike Spinoza, Aquinas distinguished between finite substances and the infinite substance. For Aquinas, man is not a mode or even an accident of a single Substance. On the contrary, a man is an individual finite substance. Moreover, in contrast with the rationalist notions of substance, Aquinas denied that a substance was something which was necessarily selfsufficient.

Instead, substance was understood to refer to a subject that maintains its identity throughout a change. Thus even finite beings could be substances because they changed while retaining an identity.

This difference in their views of substance reflects their individual methods of inquiry. As a rationalist, Spinoza began with accepted definitions of God and substance rather than arriving at them through a lengthy philosophical process. Aquinas, on the other hand, was much more empirically oriented. He started with observations of the world and then moved to his metaphysical conclusions from those observations. Naturally Aquinas knew how he arrived at his definitions of substance and accidents and thus had a fuller understanding of the concepts he employed. His definitions were derived from his observations of change in the world. He, like Aristotle, sought to account for change and identity in those things which he observed. Spinoza and Aquinas also had different understandings of what substance is.

As is noted by Wolfson, Spinoza’s understanding of substance appears to be derived from Descartes’ view of substance rather than from the medieval view. Wolfson appears to be correct in saying this. Unfortunately, the differences between Aquinas and Spinoza are often minimized by contemporary writers. Even Wolfson, who thinks that Spinoza derived his view of substance from Descartes, also said that Spinoza and Descartes started from the “medieval definition of the term”. However, even if they did start with the medieval definition, they did not have the same understanding of what substance is.

This fact becomes obvious when one looks at the results of each thinker’s philosophical system. If Aquinas thought that a substance is, by definition, causally self-sufficient he would not have claimed that finite composite substances exist. He thought that there were finite substances and he believed that those substances were dependent on God for their existence. He says, “Everything which is in any way at all must then derive its being from that whose being has no cause… Everything which is in any mode whatever, therefore is from Him.” Notice Aquinas does not say that everything which is in any mode is in God, as Spinoza says, rather he says everything is from God. Aquinas, who thought that all finite substances were dependent on God for their existence, did not have the same understanding of substance that Spinoza had.

God and His Attributes

As was mentioned above, the two different views of substance led to differences in how each thinker thought of God and His attributes. The most obvious difference between Aquinas and Spinoza concerning God and His attributes is this: Aquinas distinguishes God’s attributes from the world, while Spinoza identifies God’s attributes with the world. Spinoza thought that the world was in God. He made God so strongly immanent, that a distinction between God and the universe was difficult to grasp. Aquinas, on the other hand, viewed God as transcendent. God exists above and beyond the universe. He created the universe out of nothing, so the universe cannot be understood as a part of God. Thus, while both agree that God is an essential unity of His attributes, Spinoza counts thought and extension among the attributes of God while Aquinas does not. For Aquinas, God is not materially extended.

Thus God has His own attributes and the world has its own attributes. God’s attributes do not relate to God or to each other in the same way that beings in the world relate to their attributes. This is because God is a simple being and is not composed of any parts or principles. Ultimately, the distinction between God and the world is based on the real distinction between act and potency. God is pure act, and as such, is an essential unity of His attributes.

However, that unity of attributes does not include anything that is by its nature limited. Since potency is that which limits act, it follows that potencies should not be predicated of God who is pure act. Thus, God is an essential unity of His attributes, but He is really distinct from the world. In fact, God is so distinct from the world that the mind of man cannot conceive of God.

All of man’s concepts are of finite things. God, being infinite, cannot be conceived or even defined. Aquinas says that “God cannot be defined, for every definition is constituted from the genus and the differences.”35 Since God is not in a genus, He cannot be defined. This view of God is in stark contrast to Spinoza’s thinking. Spinoza not only thinks that God can be defined, he also thinks that God can be conceived. In thinking this, Spinoza wrongly takes previous medieval descriptions of God and illicitly turns them into definitions. This move, however, is foreign to any Thomistic doctrine of God. It should be noted that Spinoza’s moving from descriptions of God to a definition of God contributed to his thinking that the world is part of God. He mistakenly thought that God and the world could be spoken of univocally.

God’s Freedom of Will

Finally, in contrast with Spinoza, Aquinas thinks that God has a will. God’s acts are not necessitated by His nature; rather, his acts are in accordance with His nature. Aquinas shows that God has a will by showing that God has an intellect. He says that “from the fact that God is endowed with intellect it follows that He is endowed with will.” However, in some places Aquinas sounds like Spinoza in that he says God wills of necessity. For example, when speaking of God’s willing Himself to be and in speaking of God’s love for Himself it sounds as though Aquinas thinks that God’s will is necessitated by His own essence. And, in fact, Aquinas is saying that. He says, “God of necessity wills Himself to be” and “of necessity God loves Himself”. However, to conclude from this that Aquinas maintains that God wills everything of necessity would be premature.

In the very next question, Aquinas says that God does not will everything of necessity. God wills the good, but in willing Himself necessarily He wills infinite goodness. Hence, God does not need to will anything outside of Himself because He is self-sufficient in every way. He is the principle object of His own will because the will is inclined to the good and God is goodness itself. In creating the world God does not have to create every possible good. All that is required is that creation must participate in His goodness. Since He can order the world to the good in an infinite number of ways, He is not necessitated to create the world in one way or another.

Unlike Spinoza’s God, the Thomistic doctrine allows for free will in creatures as well. Aquinas maintains that God is the cause of all things, including the free choices of men. Additionally, Aquinas thinks that God is not affected in any way by the created order. However, free will is not ruled out on the Thomistic view. Even though God is the cause of everything, His causality is not of the sort that rules out free will. On the contrary, God enables finite creatures to have free will. For Aquinas, God is the primary agent who created secondary agents to act freely according to their finite natures.

Works Consulted

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________. Reality: A Synthesis of Thomistic Thought. St. Louis: B. Herder Book Co.,

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Klubertanz, George P. and Maurice R. Holloway. Being and God: An Introduction to The

Philosophy of Being And to Natural Theology. Eugene, OR: Wipf and Stock Publishers,

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