“Any of this could be argued,” he said.  And of course he was right.

I had just been giving a little talk about the natural moral law.  Among my illustrations had been the wrong of murder and theft, the rightness of marital faithfulness, the rightness of honor to parents.  In passing I had said something about the superiority of monogamy over polygamy.  That was the point that bothered him.

He was a decent man.  It wasn’t that he wanted four wives.  Nor was the problem with my arguments.

He didn’t deny that polygamy is worse for the children.  He didn’t dispute that it is worse for the union of the spouses.  He didn’t even object to the suggestion that in a polygamous society, since the rich are the ones who have multiple wives, poor men may find it difficult to win wives at all.

His only objection was that theoretically, each of these points could be argued.

The solution of the difficulty, a common one, is that there are two kinds of skepticism.  One kind destroys rationality; the other is crucial to its health.

The bad kind counsels that if anything can be doubted – in this case, monogamy -- we must not believe in it.  The problem is that everything can be doubted.  So by this rule, we should not believe in anything.  And if we suppose that we are following the rule, we will imagine that we really don’t believe in anything.

Now the plot thickens.  Practically speaking, not believing in anything is impossible.  In order to make decisions at all, we have to trust certain realities, and these are our real commitments, whether or not we realize that we hold them.  So the only thing the bad kind of skepticism accomplishes is that it keeps us from putting our commitments to the test.

The good kind of skepticism proceeds differently.  Instead of asking whether something can be doubted, it asks whether it ought to be.  Are the best reasons for it or against it?  This is the kind of skepticism Chesterton had in mind when he wrote “The object of opening the mind as of opening the mouth is to shut it again on something solid.”

Anything can be argued, yes, but at some point the guns should fall silent.

Now this fact leads to another difficulty, which I will take up next week.