How Aquinas and Feser rely on incomplete premises

It’s no secret that Edward Feser is a big fan of Thomas Aquinas. One could even say that Feser is somewhat of a ‘popularizer’ of Aquinas. In particular, Feser specializes in Aquinas’s natural theology (i.e. arguments for God’s existence). Feser himself believes that Aquinas’ arguments are airtight arguments. Naturally, I would say that I am quite skeptical of any philosophical argument being airtight. I’m not saying that Feser is claiming that his arguments contain premises that are absolutely certain (in the Cartesian sense), but Feser himself has said that Aquinas’ arguments demonstrate that God exists with ‘metaphysical’ certainty.

One of the basic ideas in Aristotle and Aquinas’ metaphysics is the idea of material causality. Material causality doesn’t mean that the material cause is always material in the sense of being physical or natural. Hence, if we were to say every effect has a material cause, we are not presupposing the truth of naturalism, materialism, or physicalism. That’s one of my objections to, for example, Aquinas’s second way (and other cosmological arguments).

My Objection

Aquinas’s second way says that every effect has a cause and that we see causes in nature. However, this is an incomplete description of what is actually happening.  What is actually happening is that we see effects with material causes. It seems that every effect has a material cause. Or, at least, people like Feser (who thinks the argument is sound) have the burden of proof to demonstrate that this causal principle is more plausible that the principle of material causality. Feser has the burden of proof because he is the one running the argument. Not only is Feser committed to the claim that God created the beginning of the universe without any “material” cause, but Feser is also committed to the claim that God is upholding the universe every second without any material cause! It’s important to note that what I’m objecting to is not the same thing as the “interaction problem” of how a incorporeal soul could cause changes in the material world. Once again, that’s NOT my objection.

But what exactly is the principle of material causality (PMC)? The PMC claims that every effect has a material cause, and/or every originating/sustaining cause has a material cause.


Feser might reply that my objection begs the question; however, this would be both a strawman and a shifting of the burden of proof. For one, I am not claiming that my principle is true or that Feser and Aquinas’s principle is false. Secondly, Feser has the burden of proof to demonstrate that his principle is more plausible than the principle I have been discussing; otherwise, Aquinas’s second way (and other cosmological arguments) is undermined. Once again, Feser has the burden of proof because he is the one running the argument and making the claim. The skeptic-one who is in doubt about an argument/premise- does not have the burden of proof. Thus, if we are in doubt about whether the PMC is true/false, then that is tantamount to being in doubt about whether Aquinas’ cosmological argument is sound. Hence, it won’t be enough for Feser to try and simply undermine the PMC; he must refute it.


So what’s the implication of my objection? Well if everything has a material cause, then creatio ex nihilo is false. In addition, God can’t sustain the universe (out of nothing) either. With respect to Feser’s interpretation of Aquinas’ cosmological arguments, the same problem arises. So even though Aquinas’ cosmological arguments are “part-whole” cosmological arguments (according to Feser), we still have the problem of God sustaining an (or multiple) essentially ordered/hierarchical series out of nothing.

A Thomist wouldn’t want to bite the bullet and give up doctrines like creatio ex nihilo. Even if they did, my objection entails that is is very far from clear why God would be needed to make sense of things like efficient/material causation. In fact, for all we know, God couldn’t play a role. [1] [2]


[1] None of this is to say that I believe that the PMC is true, nor is it to say that I think every effect has a cause (or that everything that begins to exist has a cause)
[2] I don’t think Feser has responded adequately to Humean and Kantian criticisms of Aquinas (especially Kant). Thus, I plan to make some posts about them.

17 thoughts on “How Aquinas and Feser rely on incomplete premises

      1. The commentor noted, “Newton’s first law of motion is that an object in motion will continue to stay in motion unless acted on by an opposing force.”

        The commenter then stated: “The removal of the hand in a zero-gravity, frictionless landscape (a place with no other forces) will not impede the continued motion of the stick or the rock.”

        This is incorrect. Removal of the hand means there is no force acting upon the stick to set it in motion. You can’t just “remove” from the argument the very thing the argument is about.

    1. Scalia

      Yes, Feser definitely distinguishes between per se and per accidens and with Aquinas insists that a per se causal series leads to Pure Act.

  1. Since you are asserting that a “burden of proof” exists. The burden to prove this claim is on you. I don’t believe in the burden of proof fairy, please prove she exists.

  2. wally

    The stone, stick and hand example fails because it ignores the physics behind such an arrangement.

    The particles of a stone, stick, and hand are all changing and none of those particles behave in the way that an essentially ordered series describes.

  3. Scalia

    Please recall that the Second Way is a summary (hence, the name Summa) of arguments he explicates elsewhere.

    He argues that nothing can be the efficient cause of itself because it would have to exist in order to cause its existence, and that of course is a flat contradiction. Hence, if it is caused, then it is necessarily caused by another. That of course shows us that if something can be caused, then “it” has the potential to be caused (to change from one state to another). Thus, everything that changes is a composite of two principles: act and potency. As it exists, it is in act. As it can be, it is in potency.

    It is also important to stress that Aquinas argues for a concurrent cause, not merely and accidental one. A house requires a builder, but once the builder completes the house, the house will remain if the builder dies (this is an example of an accidentally series). The house’s current existence does not depend on a sustaining cause from the builder (it does depend on other sustaining causes which furthers Aquinas’ argument, but that’s deferred for purposes of illustration). Hence, if something’s movement is dependent on the movement of another, and if that object’s movement is in turn dependent on the movement of another, then each object is but an instrumental cause, not an efficient cause. No instrument has causal efficacy, so an efficient or first mover can only explain the series (whatever that first mover is).

    These examples are merely provided to illustrate the underlying metaphysical principle that whatever changes necessarily has the potential to change, and whatever causes change must be in act (or actually exist). If something could not change, then it would be devoid of potency which means of course that it would be Pure Act. If it can change in any way, then it follows that it is a composite of potency and act.

    So, if what is causing and sustaining the existence of a thing is itself caused and sustained concurrently, then we must ask what is causing and sustaining that cause. And if that cause is itself caused and sustained concurrently, then we must ask what is causing that cause as well. The reason we keep asking is that each cause in this series is but an instrument of an efficient cause. The question of efficient cause is not answered by an appeal to something that is itself being caused. That would be akin to explaining the stone’s movement by appealing to the stick. And the reason each step in the series can even qualify as an intermediary cause is due to its act/potency composition. It must be in act in order to function as an instrument, and it must be in potency to be caused to be (as well has having other potencies). Thus, so long as we keep appealing to another act/potency step, we will cannot explain the series. The only logical stopping point is something which is not caused. And if it is not caused, then it is devoid of potency which means it is Pure Act.

    A stone’s potency to rest four feet above the floor is actualized by a table. The table’s potency to hold said stone is actualized by the floor. The floor’s potency to hold up the table is actualized by the concrete foundation. The foundation’s potential to hold up the floor is actualized by the ground, etc., etc. Hence, the stone’s position is the result of a concurrent series the causal efficacy of which is not explained by instruments which transmit causal efficacy. Every instrument which itself owes its “movement” to another cannot explain the series. It can only be stopped by something which itself does not depend on anything for its being. And the only way it can be free of such dependency is if it exists free of potency.

    Aquinas and Feser argue extensively why Pure Act must be God, but my post is long enough as it is. Of course, you’ll probably disagree with all of this, but I think it’s best to explain their argument in more detail so that readers can at least understand what Aquinas’ summary of the Second Way actually means.

  4. Irie Jackson

    The question is; did god create existent or did existent create god? I per-pose that existent, including humanity, created the concept of a supreme being to rationalize those things for which there is no rational or empirical evidence of there beginning or continuation. God (with a little g) is a concept created out of humanity’s need to know and understand, but a concept can’t be proven or disproved, it can only be believed.

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