Entailment

Keith commented on my previous post claiming that the proposition that Hobel—a moral authority (where turkeys are concerned)—eats factory-farmed turkeys entails the proposition that it is permissible to eat turkeys.

A point of clarification for those who might not be clear on the logical notion of entailment. One proposition can entail another proposition even though both propositions are false. Here's how: Let p and q stand for propositions. p entails q just in case it is logically impossible for p to be true and q to be false. In other words, to say that p entails q is to say that, necessarily, if p is true, q is true. Of course, that latter conditional—"if p is true, then q is true"—can be true even if q is false. What that conditional tells us is that if q is false, then p must be false.

Now look at Keith's claim: "That Hobel—a moral authority—eats factory-farmed turkeys entails that it is morally permissible to eat them." That claim could be true even though it is not morally permissible to eat turkeys, either because it is false that Hobel is a moral authority or because it is false that Hobel eats turkeys. It is not false that Hobel eats turkeys, but it is false that she is a moral authority. Hence, the alleged entailment that Keith mentions does not show that it is morally permissible to eat turkeys.

I also have serious doubts as to whether the alleged entailment Keith cites in his claim "That Hobel—a moral authority—eats factory-farmed turkeys entails that it is morally permissible to eat them" really is an entailment. That's because I think that it is false that "A moral authority's doing action A" entails that "doing A is morally permissible." For the sake of argument, let's mean by "a moral authority" someone who is a perfectly reliable moral authority. So defined, a moral authority knows what is right and knows what is wrong, but since it is possible to know that action A is wrong and do action A anyway, the fact that a moral authority does action A does not entail that it is permissible to do A. In short, since moral authorities can themselves act immorally, we cannot validly deduce what is permissible simply by examining the actions of moral authorities.

Note: One could, of course, define "a moral authority" as a person who is both morally omniscient and perfectly virtuous, in which case Keith's entailment claim would become analytic. But if that is what is meant by "a moral authority", then it is obvious that Hobel isn't one. No human being is morally omniscient and perfectly virtuous. Consequently, even on the analytic reading of Keith's claim, that claim gives us no good reason to think that eating turkeys is permissible.

Also note: I am not suggesting that Keith thinks that the entailment claim he makes provides any reason to think that eating turkeys is permissible. I'm sure he agrees that Hobel is not a moral authority. Rather, he is trying to make explicit the logic underlying Buckley's article to make plain how bad that argument is.