Similarly, if the prestandards issue says that the resolution is a logical truth, then one ought to be able to know that the resolution is true by logical deduction. One view you might have about logical deduction is that it’s all analytic, since you can get the rules of inference out of the Peano Postulates. This is good reason to suppose that logical truths are all a priori, since there does not seem to be such a thing as empirical analytic truths.

Most arguments which claim that there are no moral facts work similarly. There are exceptions: Gil Harman’s argument for anti-realism claims that since moral facts are not known directly through observation, we can only know they exist if they play a role in explaining facts which we know through observation. Since our explanation of the events in physical world does not require appeal to moral facts, we have no reason for believing in moral facts. This arguments turns on an explicitly empiricist assumption: that if we cannot know a fact through observation or its role in explaining observations, then that fact does not obtain. But most anti-realist arguments are not like this. Most of them say that there is something incoherent about the idea of moral facts; in other words, they’re mostly a priori.

Now I said there was something true about what Jake and Navot said. That is that when a debater calls an argument “a priori”, they usually mean that they win the round if they win this argument, that it is an atomically decisive issue or something. Often times the reason why an argument can be said to have this import is because it is a priori in the real sense (and hence it renders the resolution obviously true or false, without much more to be said about other arguments), but the fact that an argument is a game over issue or whatever and the fact that an argument can be justified a priori are not reducible to one another.

The second thing I wanted to say is that while I’m wholly convinced that we ought to exclude multiple no-risk issues, I am very skeptical about the proposal that the comparing worldviews paradigm has some better or more rigorous way of resolving that problem. I’ll write up my objections to that paradigm and post them later.

Why is that true?