The CA comes in many forms but basically it goes something like this:
All contingent beings (i.e. beings which could possibly not exist, like trees and planets) require a necessary being (a being which cannot not exist and which is not contingent upon anything else) as their ultimate cause.Feser examines nine common objections to, or misconceptions about, this argument and shows each of them to be ineffectual. It's simply incorrect, for example, to assert, as many do, that the argument rests on the premise that “Everything has a cause,” or to think that “What caused God?” is a serious objection to the argument. Neither do challenges like,“Why assume that the universe had a beginning?” or “No one has given any reason to think that the First Cause is all-powerful, all-knowing, all-good, etc.” make even a dent in the CA.
There are some contingent beings.
Thus there must exist a necessary being that is the ultimate cause of their existence.
It's a very good essay for those interested in philosophy of religion, not just for what Feser says about the CA but also for the quotes he lists from several of his atheist colleagues about the weakness of the case for naturalism.
Here's one well-known example from Quentin Smith who is an atheist philosopher of religion who writes that, "The great majority of naturalist philosophers have an unjustified belief that naturalism is true and an unjustified belief that theism (or supernaturalism) is false.” Their naturalism typically rests on nothing more than an ill-informed “hand waving dismissal of theism” which ignores “the erudite brilliance of theistic philosophizing today."
If each naturalist who does not specialize in the philosophy of religion (i.e., over ninety-nine percent of naturalists) were locked in a room with theists who do specialize in the philosophy of religion, and if the ensuing debates were refereed by a naturalist who had a specialization in the philosophy of religion, the naturalist referee could at most hope the outcome would be that “no definite conclusion can be drawn regarding the rationality of faith,” although I expect the most probable outcome is that the naturalist, wanting to be a fair and objective referee, would have to conclude that the theists definitely had the upper hand in every single argument or debate.
Due to the typical attitude of the contemporary naturalist...the vast majority of naturalist philosophers have come to hold (since the late 1960s) an unjustified belief in naturalism. Their justifications have been defeated by arguments developed by theistic philosophers, and now naturalist philosophers, for the most part, live in darkness about the justification for naturalism. They may have a true belief in naturalism, but they have no knowledge that naturalism is true since they do not have an undefeated justification for their belief. If naturalism is true, then their belief in naturalism is accidentally true. [“The Metaphilosophy of Naturalism,” Philo: A Journal of Philosophy (Fall-Winter 2001)]This and similar quotes are found toward the end of the post on Feser's blog.
I admire Smith's intellectual humility and honesty. There are few things more risible in academia than the pompous pronouncements and condescending derision of atheists like Dawkins and Hitchens who presume to lecture professional philosophers on the validity of arguments for the existence of God. It is as one observer put it, like someone whose only knowledge of biology was a familiarity with the Handbook of British Birds lecturing Dawkins on cell biology.