Aquinas’s First Cause Argument, Part 3: Essence and Existence

This is the third post in a series on Aquinas’s Second Way, or the First Cause Argument for the existence of God. In the first post I set forth some preliminary issues which it is important to understand before examining the argument. Of these issues, the most significant two are that Aquinas’s First Cause Argument is entirely different from other first cause arguments, such as the popular Kalam Cosmological Argument. The Kalam is dependent upon the universe having had a beginning; the Second Way is not. Secondly, I noted that the notion of causality itself has been contested by modern philosophers and scientists, and I explained why I would be taking real, objective causality as a given. In the second post I went into more depth about what causation is, especially what is known as “efficient causation” which is what the Second Way is built upon. I then presented the argument, which goes as such:

  1. Our senses observe essentially ordered series of efficient causes
  2. Nothing can be the efficient cause of itself
  3. Therefore, either the series of efficient causes must have a first cause, a circular regress, or an infinite regress
  4. Essentially ordered series cannot have a circular or infinite regress
  5. Therefore, there must be a first cause

In that article I stated that an efficient cause is something that actualizes a potency, and that there are different types of such causation. Examples of types of efficient causes include things beginning to exist, composite beings (beings that are composed of parts), and beings which operate within a system. All of these are examples of needs for efficient causes.

However, the argument only works for essentially ordered series of such efficient causes. In the second post I argued that there are essentially ordered series of the latter two types of efficient causes: composite beings and beings operating within a system. But it would seem, at first, that the argument doesn’t work for objects beginning to exist, because objects beginning to exist seem to just comprise an accidentally ordered series, which might in principle have an infinite regress.

Before I continue, I’d like to mention again the objection from philosopher Peter Millican, and the similar argument by Jeffery Lowder, both cited in the last post, that new things don’t actually begin to exist at all, in the sense of coming into existence out of nothing. Rather, new objects just consist of rearrangements of pre-existing matter. This objection is offered specifically against the Kalam. For our purposes, however, this objection is somewhat irrelevant. To say that something “begins” to exist does not require, on the Aristotelian-Thomistic system, that new matter come into existence. For something to begin to exist is just for the already existing matter to be rearranged in/instantiated with a new form, or essence/nature. On a physical level, the efficient cause of an object beginning to exist is just whatever causes the rearrangement of matter, e.g. an artist chiseling marble into a beautiful statue. But, again, this doesn’t seem to consist of an essentially ordered series. To repeat from previous posts, an essentially ordered causal series is one in which a cause depends upon the continued existence/sustaining power of a prior cause. Playing a piano is an example. The music coming from the piano depends upon the continued sustaining playing of a musician. An accidentally ordered series, on the other hand, is one in which an object only depends upon a single causal act. A painting wouldn’t exist without the single causal act of creation from an artist; but the painting, once created, doesn’t depend upon the continued existence or continued sustaining power of the painter. In essentially ordered series, causes receive/are imparted with their very power/ability to cause from prior causes (the hand playing the piano receives its causal power from the arm, etc). In accidentally ordered series, this is not the case. A child was caused by his parents, but he doesn’t depend upon his parents to exercise his own inherent causal power.

So, again, it would seem that for something to begin to exist is an example of an accidentally ordered series, not an essentially ordered one, and thus that the argument does not work for this instance of efficient causation. But in reality, there’s more to it than that.

Remember that I said that on a physical level, the efficient cause of something beginning to exist could just be thought of as that which causes the rearrangement of already existing matter. I also said that a new arrangement of matter would be instantiated with a new “form” or essence/nature. The real, ultimate efficient cause of something coming into existence is whatever instantiates the matter with its form.

Another way to put it is that the efficient cause of something existing is whatever gives its essence an act of existence. While this is slightly different than a form being instantiated in matter, they are similar concepts.

Philosopher Edward Feser defines what an essence is:

“The essence of a thing is just that which makes it the sort of thing it is…It is also that through which a thing is intelligible or capable of being grasped intellectually” [1].

And elsewhere:

“The essence of a thing is its nature, that whereby it is what it is. It is what we grasp intellectually when we identify a thing’s genus and specific difference” [2].

For Aquinas, there is a distinction between essence, or what a thing is, and existence, or that it is [3]. The essence of a human, for example, is “humanity,” or, as Aristotle defined it, “rational animal.” The essence of, say, a triangle, is to be a geometrical shape with three sides the sum of whose angles measures 180 degrees, etc. We can even think of the essences for mythical creatures, such as a unicorn, whose essence would just be a horse-like-animal that has a single horn protruding from the top of its head. But this raises an interesting question. Why do some essences actually exist and others not? Or, in other words, why do essences actually exist at all? There doesn’t seem to be anything about the essences of objects around us in themselves that cause them to exist and keep them in existence from moment to moment. As such, there are several possible reasons that support Aquinas’s doctrine that essence and existence are distinct:

First, knowing the essence of a being doesn’t tell you whether or not it actually exists. Suppose that some intelligent alien species from a distant galaxy was given a list of descriptions of all the different animals that live on earth, and included in the list were descriptions of mythical creatures such as unicorns, centaurs, phoenixes, dragons etc. Would the alien have any way to tell, just by the descriptions, which animals are real and which are not? Most likely not. After all, there’s nothing about the description of the essence of “a horse-like-animal that has a single horn protruding from the top of its head” that is any less bizarre than that of the actually existing narwhal, or “an aquatic mammal that has a single horn protruding from the top of its head.” There’s just nothing about the essence of beings in itself that tells us whether or not it actually exists. This would seem to support the idea that essence and existence are distinct. As Feser puts it, “if it is possible to understand the essence of a thing without knowing whether it exists, its act of existing (if it has one) must be distinct from its essence, as a metaphysically separate component of the thing” [4].

Secondly, beings that do actually exist in the universe certainly don’t have to exist, as is evidenced by the fact that they come into and go out of existence frequently. Most biologists would not contend that horses or humans or any other species had to evolve the way that it did. And the individuals in all these different species come and go all the time. The same is true for all other different types of beings, from rocks and trees to stars and planets and molecules. If their existence were inherent to their essence, then this would not be the case. If something’s existence were inherent to its essence, it would always have existence, and it would never come into being or go out of being. Thus:

“Whether it’s people or trees, unicorns or elves, their essence is one thing and their existence (or lack thereof) another, and the first doesn’t entail the second. But then, the essence or nature of the thing in the universe can’t be what accounts for their continuing to exist from moment to moment” [5].

Since all the objects around us in the physical universe do not have existence intrinsic to their essences, then there must be something which “conjoined” their essence with the act of existence. We can think of an essence as a potential, and existence as actuality. A unicorn could potentially exist; there’s nothing in such an essence which makes it logically incoherent or metaphysically impossible. But it doesn’t exist; it’s essence hasn’t been actualized. According to Feser:

“a form or essence is only ‘potential’ relative to existence or being. Existence or being is what ‘actualizes’ a form or essence. Now if the essence of a thing and the existence of the thing are distinct in this way–there is nothing in the former that entails the latter–then something needs to put them together if the thing is to be real” [6].

An efficient cause, then, is whatever it is that conjoins a being’s essence with existence. Earlier I said that on a physical level, an efficient cause is whatever causes pre-existing matter to come into a new arrangement. But on a deeper, metaphysical level, whenever we speak of something “coming into existence” we speak of its essence being given an act of existence.

It is also important to note that once something’s essence is joined with an act of existence, the two do not suddenly become identical. They are still distinct metaphysical components, they have just been conjoined together. If something’s essence does not intrinsically contain existence, it can never intrinsically contain it; when the two are joined, the essence is just given existence extrinsically. Feser extrapolates:

“a thing’s essence and act of existing are distinct not just before it exists, but always, even after they are conjoined so as to make the thing real…Hence it is not enough for a thing to be real that its essence and act of existing be conjoined merely at some point in the past; the essence and act of existing must be kept together at every point at which the thing exists. Accordingly, a thing must be caused to exist not once for all, but continuously, here and now as well as at the time it first came into being…it must be conserved in existence from moment to moment” [7].

So the initial cause of your existence is your parents. But your parents do not sustain your existence here and now, from moment to moment. And yet, since you are a being whose essence is distinct from its act of existence, something must here and now be conserving your existence. Aquinas thought that the only thing which could conjoin essence with existence is God, for reasons which we shall examine later. For now, it is not even necessary to concede this. Even if we just think that what is here and now holding together my essence and act of existence is the composite effort of atoms and molecules which make up my body, and the physical forces and fundamental particles which those consist of, etc., even then it becomes evident that we have an essentially ordered causal series which must terminate in a First Cause. Because each of the atoms, molecules, and particles which make up my body and everything else that exists, are also beings whose essences are distinct from their act of existence. Thus the essence of an atom, molecule, or fundamental particle must also be here and now conjoined to an act of existence by some efficient cause. There must be some First Cause which conserves the existence of all other beings whose essences are distinct from the act of existing. And this being must necessarily be a being whose essence and act of existing are not distinct; that is to say, there must exist a being whose essence and existence are identical, a being whose essence intrinsically contains existence, a being whose essence is existence itself. Feser explains:

“the only thing that could possibly stop the regress and explain the entire series would be a being who is, unlike the things that make up the universe, not a compound of essence and existence. That is to say, it would have to be a being whose essence just is existence; or, more precisely, a being to whom the essence/existence distinction doesn’t apply at all, who is pure existence, pure being…not being, strictly speaking, but Being Itself” [8].

Now this argument about the distinction between essence and existence that I have presented in this post is, technically, an entirely separate argument from Aquinas’s Second Way. The Five Ways are found in Aquinas’s massive Summa Theologica, but this argument is found in his On Being and Essence, and is often referred to as “the Existential Proof”. In fact, it works as an argument all on its own, completely separate from the Second Way. Likewise, the Second Way, as I argued in the last post, can succeed independently from the distinction between essence and existence. Some philosophers think the Existential Proof ought to be delivered on its own. Some think that it should be used in one or more of the Five Ways. And some, such as Edward Feser, whose writings I have been using to help explain the argument, think it ought to be interpreted in light of the Second Way, as I have done here. In any case, it certainly supports and adds force to the First Cause argument, in that it shows that not only do we need a First Cause for essential series consisting of composite beings and beings which operate within a system, but we also need a First Cause for beings which begin to exist, for beings whose essences are distinct from the act of existing; and this First Cause must sustain their existence here and now, at every moment. Furthermore, the Existential Proof tells us something, and something overwhelmingly significant, about what this First Cause is: its nature is existence itself, it is Being Itself. Or, as Aquinas calls it, Ipsum Esse Subsistens or “Subsistent Being Itself” [9].

What is this Subsistent Being Itself like? Can we know any of its attributes? Can we in any sense call it God?  In my next post I will be answering these questions, as well as looking at some final objections to the argument in general.




[1]. Feser, Edward. Aquinas. London: Oneworld Publications, 2009. Print, 24.

[2]. Feser, Edward. Scholastic Metaphysics: A Contemporary Introduction. Piscataway: Editiones Scholasticae/Transaction Books, 2014. Print, 211.

[3]. See  Feser, Ed. The Last Superstition: A Refutation of the New Atheism. South Bend: St. Augustine’s Press, 2008. ebook.

[4]. Feser, Edward. Aquinas. London: Oneworld Publications, 2009. Print, 29.

[5]. Feser, Ed. The Last Superstition: A Refutation of the New Atheism. South Bend: St. Augustine’s Press, 2008. ebook.

[6]. ibid.

[7]. Feser, Edward. Aquinas. London: Oneworld Publications, 2009. Print, 85.

[8]. Feser, Ed. The Last Superstition: A Refutation of the New Atheism. South Bend: St. Augustine’s Press, 2008. ebook.

[9]. See here: <>.


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