We’re using the book “Handbook of Apologetics” by Peter Kreeft and Ronald Tacelli to go over the arguments for the existence of God. Dr. Kreeft teaches logic in two major universities, so his arguments tend to be clear, concise and very helpful.
This week we’ll go over questions about the argument from desire:
Question 1:
How can you know the major premise—that every natural desire has a real object—is universally true, without first knowing that this natural desire also has a real object? But that is the conclusion. Thus you beg the question. You must know the conclusion to be true before you can know the major premise.
Reply: This is really not an objection to the argument from desire only, but to every deductive argument whatsoever, every syllogism. It is the old saw of John Stuart Mill and the nominalists against the syllogism. It presupposes empiricism—that is, that the only way we can ever know anything is by sensing individual things and then generalizing, by induction. It excludes deduction because it excludes the knowledge of any universal truths (like our major premise). For nominalists do not believe in the existence of any universals—except one (that all universals are only names).
This is very easy to refute. We can and do come to a knowledge of universal truths, like “all humans are mortal,” not by sense experience alone (for we can never sense all humans) but through abstracting the common universal essence or nature of humanity from the few specimens we do experience by our senses. We know that all humans are mortal because humanity, as such, involves mortality, it is the nature of a human being to be mortal; mortality follows necessarily from its having an animal body. We can understand that. We have the power of understanding, or intellectual intuition, or insight, in addition to the mental powers of sensation and calculation, which are the only two the nominalist and empiricist give us. (We share sensation with animals and calculation with computers; where is the distinctively human way of knowing for the empiricist and nominalist?)
When there is no real connection between the nature of a proposition’s subject and the nature of the predicate, the only way we can know the truth of that proposition is by sense experience and induction. For instance, we can know that all the books on this shelf are red only by looking at each one and counting them. But when there is a real connection between the nature of the subject and the nature of the predicate, we can know the truth of that proposition by understanding and insight—for instance, “Whatever has color must have size,” or, “A Perfect Being would not be ignorant.”
Kreeft, P., & Tacelli, R. K. (1994). Handbook of Christian apologetics: hundreds of answers to crucial questions (pp. 79–80). Downers Grove, IL: InterVarsity Press.