I'll begin my critique of Layman's book is with the following quote (This is an abridgment of a review on my website.):
"Just as a contingent truth is true but might have been false, so a contingent being is one that does exist but might not have. And suppose we claim, with regard to any contingent being, that it exists, e.g.,"I (Zach) exist" or "You (Thomas) exist." Such propositions are contingent truths, not necessary ones. More generally, we can state the relationship between contingent beings and contingent truths as follows: A being is contingent if (and only if) every proposition affirming its existence is a contingent truth. (p. 85)"
Not in the above quote, nor anywhere else in the book, does he say that humans are finite beings and that God is an infinite being. I agree that humans are contingent beings, but this is not as clear and unmistakably true as the proposition that humans are finite beings: Zach exists and Thomas exists, but Zach is not Thomas and Thomas is not Zach. Zach and Thomas are different beings, that is, finite beings. God is a being that is not finite. A finite being needs a cause outside of itself whereas an infinite being can be the reason for its own existence. Since the universe would be unintelligible if every being needed a cause, there must be at least one infinite being. QED.
Layman is butting heads with the Roman Catholic Church and St. Paul as can be seen from the following quote from the Baltimore Catechism:
"22. Can we know by our natural reason that there is a God?
We can know by our natural reason that there is a God, for natural reason tells us that the world we see about us could have been made only by a self-existing Being, all-wise and almighty.
For the wrath of God is revealed from heaven against all ungodliness and injustice of those men that detain the truth of God in injustice; because that which is known of God is manifest in them. For God hath manifested it unto them. (Romans 1:18-19)"
The use of the word "know" and the phrase "wrath of God" constitutes a criticism of the character of naturalists, atheists, and agnostics. Layman says it's the best explanation without criticizing those who disagree.
One of Layman's arguments is that the "theistic hypothesis" gives a better explanation for the fact than humans have free will than naturalism, the philosphy that there is no supernatural being. Layman begins his argument by attempting to define free will:
"Free will is traditionally characterized as the power to do otherwise than one in fact does. Let's say you recently voted in a meeting by raising your right arm. If you performed this action freely, then you had the power to do otherwise, to refrain from raising your right arm. If you have free will, then when you face a decision between incompatible courses of action (such as speaking and refraining from speaking), although you cannot take more than one of them, each of them is within your power. Another way to put it: If you have free will, then when you are confronted with mutually exclusive courses of action, which one you take is genuinely up to you. (p. 139)"
All he is saying here is that free will is free will. It is another example of circular reasoning. Undaunted by or unaware of his inability to define free will, he goes on to discuss related concepts at great length: mechanism, determinism, compatibilism, and incompatibilism. I agree, however, with the following statement he makes about naturalists:
Many naturalists deny free will altogether because they see it as incompatible with a world governed by natural law. (p. 162)
I think I can do a better job than Layman of explaining why naturalists deny humans beings have free will. A "world governed by natural law" is a world in which there are no persons exercising their freedom. All Layman is saying is that naturalists deny free will because they don't think there is such a thing.
People who deny humans have free will in philosophical arguments act as if they had free will in the day-to-day living of their lives. They have the same experience we all have of existing, being aware of our existence, and acting through time. If they do something wrong they feel guilty, apologize, and promise not to do it again. If they work hard on a project for a few hours or a few days, they take pride in what they did. Their denial of free will is not only irrational, it raises questions about their sincerity and motives.
We can comprehend ourselves and recognize that we are finite beings, but we cannot otherwise define ourselves since we cannot define free will. This leads rational philosphers to say man is an indefinabilty or an embodied sprit, or that man possesses a spiritual soul as well as a body. Thomas Aqinas's formulation was that man is a compostion of two incompelete beings: a material incomplete being and an immaterial incomplete being that are metaphysically combined to form one being.
By denying free will, naturalists are really admitting, however perversely, that they agree with the logic of the proof of God's existence: If humans have free will, then they are finite beings. If finite beings exist, then an infinite being exists. If their motive for denying free will is not to refute the proof of God's existence, what is it?
I did not invent the proof of God's existence which is sometimes called the "cosmological argument." It can be found, for example, in the Baltimore Catechism:
"10. What do we mean when we say that God is self-existing?
When we say that God is self-existing we mean that He does not owe His existence to any other being.
I am who am. (Exodus 3:14)"
While the answer to the question is as vauge and circular as Layman's "theistic hypothesis," the use of Exodus 3.14 as a proof-text shows the authors understand the proof, which is based on Aquinas's analysis of finite beings. According to Aquinas, a finite being has two principles operating within it: an essence and an existence. To quote from the glossary of a textbook on metaphysics (N. Clarke, One and the Many):
"Essence = that in a being which makes it to be what it is, this being and not some other.
Existence = that is a being which makes it a real being."
An infinite being can be thought of as a being which does not have a separate essence and existence. In other words, an infinite being's essence is the same as its existence. Its essence is to exist. Just as God told Moses.