OK. Maybe I care just a little bit.

I summarized my complaint against Aquinas’ Five Ways this way (in response to a comment from Jeff Lowder):

I’m just pointing out that (a) NONE of the Five Ways is an argument for the existence of God as it stands (in the section called “Whether God Exists?”), and (b) in order to make use of any of the Five Ways as an argument for the existence of God, there is a serious amount of intellectual effort required to fill the logical gap that is located in the space where Aquinas dropped this philosophical turd: “to which everyone gives the name of God.”

I also re-iterated a similar complaint against William Craig:

This seems to be a bit of a habit for William Craig. Craig is literally a half-ass thinker. His case for the resurrection is half-assed because he completely ignores the question of whether Jesus died on the cross, which is HALF of his burden of proof. In most of the presentations of the Kalam cosmological argument that I have read, Craig makes only brief and cursory attempts to argue that the cause of the beginning of the universe is God. So, on two of the most central issues of Christian apologetics, Craig leaves half the argument largely untouched.

However, the writings of Aquinas are extensive, and he has a lot to say about God, so as Peter Kreeft points out, we cannot properly evaluate Aquinas’ case for God based just on the presentation of the Five Ways in Summa Theologica (Part I, Question 2, Article 3:”Whether God Exists?”):

These five are not the proofs themselves but ways, i.e. indications or summaries of proofs. The proofs themselves are elsewhere worked out in much greater detail; e.g. in the Summa contra Gentiles the first way takes thirty-one paragraphs (Bk 1 Chap. 13); here it takes only one. (Summa of the Summa, p.61)

Although I’m sticking to my guns on the two points of criticism against Aquinas above,  I have to apologize to Aquinas (and his fans) for the implication that he was a “half-ass thinker” (given my unkind comparison of Aquinas with the half-ass philosophers William Craig and J.P. Moreleand).  A wider look at the works of Aquinas reveals that he actually DOES make an argument for the existence of God, just not in the section of Summa Theologica called “Whether God Exists?”.  I will outline Aquinas’ argument for God a bit later in this post.

I took a look at the passage in the Summa contra Gentiles that Kreeft pointed to as presenting the First Way in greater depth and detail.  That passage does provide a more detailed expostion of the argument for the existence of an unmoved mover, but Aquinas makes NO ATTEMPT (in that section of Summa contra Gentiles) to argue that an unmoved mover has ANY of the major divine attributes (i.e. personhood, creator of the universe, eternally omnipotent, eternally omniscient, eternally perfectly good). Aquinas just goes into greater detail and depth to argue that there exists an unmoved mover.  So, in the section of Summa contra Gentiles that Kreeft points us to, Aquinas still does NOT present an argument for the existence of God.

Kreeft is correct that the Five Ways passage is only a summary of reasoning that Aquinas presents in greater detail and depth elsewhere.  However, Kreeft fails to point out a very basic and important point about the content of the Five Ways:  they represent only the FIRST PHASE of an argument that consists of at least FIVE PHASES.  So, the Five Ways are summaries of more extensive reasoning, but they are NOT summaries of Aquinas’ argument for the existence of God; they are summaries of the FIRST PHASE of his multi-phased argument! (I suspect that Kreeft is not aware of Aquinas’ actual argument for the existence of God, otherwise he would have mentioned this very important point).

The fact that it takes Aquinas four more phases of argumentation to finally get to the conclusion that God exists shows that my objection was absolutely spot on when I complained that “there is a serious amount of intellectual effort required to fill the logical gap that is located in the space where Aquinas dropped this philosophical turd: ‘to which everyone gives the name of God.’ ”  Aquinas does make a serious attempt to fill in that HUGE logical gap; you just have to search through his various writings to find this intellectual effort.

I turned to A Critical History of Western Philosophy (edited by D.J. O’Connor; hereafter: CHOWP) in hopes of getting a better perspective on Aquinas’ thinking about God, and was delighted to find an excellent article on Aquinas by Knut Tranoy.  The article expresses an objection similar to mine, perhaps a bit more clearly than my own attempt to express it:

Granted that each argument is in order as it stands, we then have five different series, each terminating in a “first” which is, respectively, a prime mover, a first efficient cause, a necessary being, a supreme perfection, and a designer or governor of the universe.  In order to amount to a proof of the existence of God, it must then also be shown that (1) the five series converge in one and the same point (the prime mover = first efficient cause, etc.), and (2) that the point of convergence has all the properties which the God of Christianity is said to have.  And this Thomas does not show.  (CHOWP, p.110)

The criticism in the last sentence has an unstated qualification: Thomas does not show these two key points in the passage on the Five Ways in Summa Theologica.  Tranoy goes on to describe how Aquinas does address at least point (2) in other passages and other books.

Tranoy makes a basic point of logic that Aquinas was apparently unclear on:

To prove or to produce evidence that a certain being x, exists, is, one might say, to prove that a certain set of compossible properties is actualized.  That is, we cannot prove or know that x exists without at the same time knowing something about the nature or essence of x.

To prove the existence of God is, then, to show that the properties ascribed to the Christian God in the Bible are actualized in one and only one being.  At least our proof must show that the property or set of properties is actualized from which all the other required properties necessarily follow.  (CHOWP, p.110)

Aquinas should have started out with a definition or analysis of the word “God” that spells out what this word means in relation to the Christian faith (or perhaps in relation to the big three western theistic religions: Judaism, Christianity, and Islam).  The definition or analysis would contain the main divine attributes, such as:  bodiless person, creator of the universe, eternally omnipotent, eternally omniscient, eternally perfectly good.  After proving the existence of an unmoved mover and a first efficient cause, etc.  He should have immediately argued that these beings were a single being, and then he should have argued that this single being has all (or perhaps most) of the main divine attributes that constitute the definition/analysis of the word “God” from a Christian point of view. Aquinas did not proceed this way.

However, based on Tranoy’s explication of Aquinas’ thinking about God, it appears that one can piece together from various writings by Aquinas an argument for the existence of God that involves at least FIVE PHASES.  Tranoy has a little diagram that lays out the logic at a high level (see CHOWP, p.112), and I have added some details and distinctions to his diagram to produce the following chart (click on the image for a clearer view of the chart):

The arguments that constitute the Five Ways are summaries of the reasoning in support of Phase 1 (particularly Way 3, which argues for a “necessary being” i.e. a being that is ipsum esse subsistens).  Thus, Aquinas’ argument for the existence of God is like an iceberg, and the Five Ways are merely the visible tip of that iceberg.  MOST of the argument is invisible in the section of the Summa Theologica that is called “Whether God Exists?”.  MOST of the argument is simply missing from the presentation of the Five Ways in that passage.

The overall logic is that Aquinas first establishes the existence of a being with various “metaphysical” properties, and then on the basis of that conclusion he argues for the existence of a being who has various “religious” properties, the divine attributes that constitute the meaning of the word “God” from a Christian or religious point of view (I think this line of reasoning could also be used by Jewish or Muslim apologists to defend their belief in the existence of God).  The effort to establish the existence of a being with various metaphysical properties involves three phases:

1. Show the existence of beings that each have a core metaphysical property.

2. Show that these beings with a core metaphysical property are the same being.

3. Show the existence of a being with a variety of derived metaphysical properties (logically derived from the core metaphysical properties).

The next two phases are concerned with establishing the existence of a being with a variety of religious properties:

4. Show the existence of a being with a core religious property (i.e. perfect knowledge).

5. Show the existence of a being with various derived religious properties (logically derived from the core religious property and from previously established metaphysical properties).

Once Phase 5 is completed, it is a short step of logic to the ultimate conclusion: God exists.

Recall that in Summa contra Gentiles, Aquinas writes several pages of reasoning just to arrive at the Phase 1 conclusion that there exists an unmoved mover.  I don’t know if Aquinas goes into the same degree of detail and depth in his reasoning supporting the other phases of his argument, but I would not be surprised if he did.  I’m not certain that Aquinas argues for the claim of Phase 2 (that the IES being and the AP being are the same being), but I suspect that he does.  According to Tranoy, Aquinas does provide reasoning is support of the other Phases of the argument.

I strongly suspect that there are logical errors and dubious assumptions sprinkled throughout the long and complex development of this line of reasoning by Aquinas, and that I will find multiple reasons to reject his “proof” of the existence of God, but at least Aquinas made the attempt, at least he realized, at some level, that there was a huge logical gap in the argument presented in the passage laying out the Five Ways.  

Aquinas, unlike Craig and Moreland, recognized that there was a large logical gap between establishing the existence of a being with a metaphysical property (like being an “unmoved mover” or a “first efficient cause”) on the one hand, and the existence of God on the other.