My main purpose will be to look at one thing only: does Dr. Feser present any sort of proof that atheism is untenable, and in particular for his version of God? I have read a variety of comments on Dr. Feser, his variations on the teaching of historical figures, his own associations, etc., from comments on this blog and elsewhere. I understand that many of them are probably legitimate, but I'm not going to address them. Other topics, such as the nature of morality or the practical and political applications thereof will creep into the discussion only because Dr. Feser insists that his proof is evidence that his own particular brand of theism offers these positions obvious rational support. I'm also not going to address the judgemental rhetoric, except to examine any underpinnings they seem to be stemming from, as I don't particularly care what Dr. Feser's opinions are nor how he states them. Further, my goal is to address Dr. Feser's argument on his own ground, in his own terms. Any argument crafted with so much effort deserves at least that much.
Dr. Feser starts with a quote of Plato and then follows with this quote from Aquinas, "A small error in the beginning of something is a great one at the end." I find it ironic that even at the beginning (the preface) of his book, we find errors of category and an error of fact. Now, I don't think these particular errors will be overly relevant to Dr. Feser's argument (certainly not the error of fact), but that just makes them small errors. Whether they have blossomed into great ones at the end, I don't know yet (I'm still in Chapter 2). Both of these errors appear in the same passage:
It is no more up the courts or "the people" to "define" marriage or to decide whether religion is a good thing than it is up to them to "define" whether the Pythagorean Theorem is true of right triangles, or whether water has the chemical structure H2O. In each case, what is at issue is a matter of objective fact that it is the business of reason to discover than democratic procedure to stipulate.
Just in case you were wondering whether Dr. Feser means that the Pythagorean Theorem is actually true, he leaves no doubt of that in chapter 2 when discussing Platonic Forms: he does indeed mean the Pythagorean Theorem is true as a real-world proposition. This is of course an error. In a formal system where all of Euclid's postulates hold, the Pythagorean Theorem is deducible. However, not all of Euclid's postulates hold in reality (in particular, the postulate regarding lines crossed by a transversal meeting on the side of line where the sum of the interior angles is smaller than 180 degrees, the equivalent to the parallel postulate, does not hold). So, for the followers of realism (as is Dr. Feser), the Pythagorean Theorem is actually false.
The second error is more subtle, and I doubt Dr. Feser would even agree. The types of knowledge used, and the ways that we decide, what marriage is and whether religion is good is completely different from how we derive the Pythagorean Theorem, and the knowledge that H2O is water is a third way of knowing what is true. The three are not comparable. In fact, we aren't completely certain H2O is the formula for water, the Pythagorean Theorem is not real (nor any other purely mathematical concept), and my strong suspicion is that there can be no demonstration of a proper definition for marriage or the goodness of religion.
To their minds (or what is left of them) sexual libertinism and contempt for religion, as public, mass phenomena (rather than the private eccentricities of a decadent elite, which of course have always been with us) constitute the final victory of reason ...
Isn't nostalgia great? How all those ordinary people were so sexually moral that prostitution was practically unknown, were so religious that they never cursed God and went to church every day. Not to mention, and maybe he missed this, but a modern lower-middle class family of today would be part of the elite back in the days of Aquinas. So, even if his position is true, the modern libertinism and contempt represent no change at all from previous times except for the higher percentage of the population in the elite status.