Jerry Coyne just posted an article titled, “Paul Bloom debunks the ‘Moral Law argument for God.’” I found myself getting irritated as I read the article because it’s obvious Coyne doesn’t know what he is talking about.

Before we get to Bloom’s findings, what is the “moral law argument”? It’s simply this: human altruism can’t be explained by any kind of evolution. What I mean is pure altruism, whereby an animal helps another animal not only unrelated to it, but not part of its social group, and helps in such a way that it sacrifices its own reproductive potential without getting anything back.  It’s unrequited altruism. That kind of behavior simply can’t evolve, at least by natural selection, because it reduces the fitness of the performer.

No. That is NOT “the moral law argument” defended by C.S. Lewis in Mere Christianity. Coyne is attacking a straw man argument.

First, we need to be clear that there is no such thing as “the” moral law argument. There are many moral arguments. D’Souza, in his book, What’s So Great about Christianity?, defends an argument I’ve called the “Moral Laws Require a Moral Lawgiver” argument. I invite the reader to click that link, see my summary of that argument, and decide for themselves whether Coyne’s post has anything at all do with that argument.

Turning to Collins, I don’t have a copy of Collins’ book handy as I’m writing this post, but Collins explicitly says that he was convinced by C.S. Lewis’s moral argument. When reading Collins’ book, I remember thinking to myself, “Collins is pretty much making the same argument Lewis did; he’s just adding on some information about sociobiology.” It could be the case that Collins did make the absurd claim that atheism cannot explain moral emotions; I’d have to go re-read his book to find out. But, even if he did make such a claim, Coyne would still be guilty of attacking a straw man because there is much more to Lewis’s argument (and Collins’s defense of it) than an appeal to known facts about moral psychology (i.e., moral emotions). The focus of the argument is about the Moral Law, but Coyne writes as if Lewis, Collins, D’Souza had only talked about altruism and said nothing about moral ontology (or moral epistemology).

Let’s review what Lewis actually wrote, since a quick summary of Lewis’s argument (which is defended by Collins) will show that Coyne has simply missed the point of the argument. Lewis’s book, Mere Christianity, was originally delivered over the radio for BBC for a popular audience and only later printed as a book. So he didn’t present his argument in its logical form, with neatly labeled premises and a conclusion. Nevertheless, I think we can quite easily place his argument into is logical form. The first thing to note is that Lewis was making an explanatory argument, i.e., he was arguing that God (in his words, the “Religious View”) is the best explanation for certain known facts about the Moral Law.

Let’s begin with some definitions:

“materialist view”: the hypothesis that there is no Mind “behind” the universe (i.e., there is no Creator). The universe itself, as well as all the creatures inside it (including humans), are not the effect of a supernatural First Cause or intelligent Designer.

“Religious view”: the hypothesis that there is a Mind behind the universe which caused and designed the universe, partly to produce creatures that, like It, have minds.

Lewis includes three statements in the background information relevant to his explanatory argument.

1. The materialist view entails that there is no Mind “behind” the universe (i.e., there is no Creator). The universe itself, as well as all the creatures inside it (including humans), are not the effect of a supernatural First Cause or intelligent Designer. (21-22)

2. The Religious view entails that there is a Mind “behind” the universe (i.e., there is a Creator who is conscious, has purposes, and preferences). This Mind created and designed the universe partly to produce creatures that, like It, have minds. (22)

3. A Mind “behind” the universe could reveal Its existence to us by trying to get us to behave in a certain way. (24)

Lewis says that there are three facts about the Moral Law which need explanation.

1. Human beings have moral obligations which are grounded in the Moral Law.

2. Most human beings know at least the general principles of the Moral Law.

3. Most human beings experience moral emotions related to the Moral Law, such as guilt and obligation.

Using this distinction between background information and the evidence to be explained, Lewis’s argument becomes a straightforward explanatory argument.

(1.) The evidence relevant to the Religious view is known to be true. [Note: this evidence is composed of the three facts just listed above]

(2.) The materialist view has weak explanatory power, i.e., the evidence to be explained is very improbable if the materialist view is true.

(3.) The Religious view has strong explanatory power, i.e., the evidence to be explained is very probable if the Religious view is true.

(4.) So, the Religious view is the best explanation of the relevant evidence.

(5.) Therefore, the Religious view is probably true.

This summary of C.S. Lewis’s argument should make it immediately obvious that Lewis, at least, does NOT make the absurd claim that “human altruism can’t be explained by any kind of evolution” (my emphasis). Coyne, of course, is correct that evolution can explain human altruism. But that doesn’t refute Lewis’s argument. First, Coyne’s post is irrelevant to Lewis’s claims about moral obligations and moral knowledge/beliefs.

Second, even when it comes to Lewis’s point about moral emotions, such as guilt and obligation, Coyne still misses the mark. An explanatory argument, as the name implies, is an argument about which hypothesis gives the best explanation. It’s logically incorrect to claim an explanatory argument for some hypothesis A is refuted by the fact that some other hypothesis, B, can also explain the evidence. Even if that’s true–in other words, even if B can also explain the evidence–that’s irrelevant. All that matters is whether the explanatory argument’s comparative claim, that A is a better explanation than its competitors, is true.

This shows that Coyne needs to do more than simply show that evolution can explain moral emotions. He needs to directly refute the claim that God is the best explanation for moral emotions, either by showing that an evolutionary explanation is as good as a theistic explanation or by showing that an evolutionary explanation is better than a theistic explanation. Coyne doesn’t do either of those things, however. The closest Coyne comes to doing this is when he talks about how the evolutionary explanation is “more parsimonious” than the theistic explanation. That’s a good point as far as it goes, but it doesn’t go far enough to successfully refute the explanatory argument. It doesn’t show that the parsimony of the evolutionary explanation is so great as to outweigh the (alleged) superior explanatory power of the theistic explanation.