This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.


Hi Dr Craig.

I've heard you say, on the topic of marriage, that you are an "essentialist" on the nature of marriage- that is, marriage has a certain intrinsic nature which is not merely a social construct. As a natural law theorist who thinks the moral law is grounded in what it is to be human, this gratified me immensely. On the other hand, you are also well-known for your nominalism on the topic of abstract objects, which I take to be the denial that there are real universals in any sense (either Aristotelian or Platonic). My question is how these positions can be made consistent.

As far as I know, to an essence just is a universal, so to affirm that marriage has an essence seems in direct contradiction with the idea that there are no such things as universals. Since I don't think you would permit so obvious a contradiction, either my account of essence or my understanding of your nominalism must be at fault. I would be much gratified if you could elaborate, as I think it would help me better understand your position on abstract objects.



Dr. William Lane Craig’s Response

Dr. William Lane Craig

Matthew, your question illustrates exactly the reason I have avoided the term “nominalism” as a label for my views on the reality of abstract objects and chosen “anti-realism” instead.

In the history of theology “nominalism” has become something of a dirty word because of its associations with conventionalism and relativism, just as you suggest. But that is no part of contemporary anti-Platonism. Just as saying, “Mars has two moons” does not commit you to the existence of some weird abstract object we call 2, so saying, “Marriage is essentially (or by definition) a union between a man and woman” does not commit you to some abstract object which we call the essence of marriage. “The essence of marriage” is not meant to be a heavyweight, metaphysical term, but convenient shorthand for talking about the way marriage necessarily is.

Presumably, as a theist, you don’t think that the natural law is some non-spatiotemporal, immaterial, causally effete, abstract object with which God finds Himself confronted. Isn’t it better to say that the natural law finds it source in God and His will or commands? For example, we can affirm that God has necessarily decreed that human beings are to be treated as ends in themselves rather merely as means to ends. “The natural law” shouldn’t, or needn’t, be taken to be a metaphysically heavyweight term but just a convenient way of talking, for example, about the intrinsic value of human persons and what moral obligations/prohibitions we have to fulfill.

The overall lesson here is: don’t read ontology off of language.

This post and other resources are available on Dr. William Lane Craig's website:

Learn more about Dr. Craig’s book, A Reasonable Response.