Contrastivism holds that the truth makers for knowledge attributions always involve a contrast, and Hawthorne thinks that if you know something, you are entitled to use it in practical reasoning. So one way to test what it is known is to see what kinds of practical reasoning we’ll allow are acceptable.
Depending on what the contrast is, contrastive knowledge may be easy or hard to have. So, it is easier to know “the train will be on time rather than a day late” than it is to know “the train will be on time rather than 2 minutes late.” One way to put the difference is that one is presupposing more in knowing the first claim that one is in knowing the second.
Consider then a piece of practical reasoning using the following conditional: if you are pointing a gun at me, and if your gun is loaded and if you intend to shoot me, I should shoot you first. Suppose I know that you are pointing a gun at me rather than a twig, and that I know that your gun is loaded rather than having just been disassembled for cleaning, and suppose I know that you intend to shoot me rather than give me a million bucks. Should I shoot you? Maybe this is an anti-gun sentiment coming out, but I think it is far from obvious that I should.
Compare this case to another. In this case, I know that you are pointing a gun at me rather than any non-lethal item, and I know that your gun is loaded rather than merely having the appearance of being loaded from where I stand, and I know that you intend to shoot me rather than anyone else in the universe. Now I think I should shoot you first.
Why the difference? In contrastivist language, I’m presupposing too much in the first case, I think. The knowledge I have is easy knowledge because it presupposes so much. I’m presupposing that the thing in your hand is either a gun or a twig, that it’s either loaded or disassembled, that you intend to shoot me or make me rich. In the context of these assumptions, it’s too easy to come to the conclusion that I should shoot first and ask questions later. In the second, case, however, my presuppositions are much broader, broad enough that my knowledge is no longer easy. And since my knowledge is not easy, I doubt I could be faulted on grounds of rationality for shooting first.
It appears, then, that contrastivists will have to deny Hawthorne’s principle. Moreover, I don’t see any obvious way to qualify the principle for the following reason. If the action is relatively inconsequential, then easy knowledge may be enough to warrant performing the action. But if the action is immensely significant, as it is in the case of taking a life, then easy knowledge doesn’t seem to be enough.
One way to think about such cases is that they may provide a reason for including pragmatic issues in one’s account, either indirectly as contextualists typically do or directly as we find in the invariantist camp. Or maybe a reason for rejecting Hawthorne’s principle…?