a1 Philosophy, Massachusetts Institute of Technology
Moral theorists often say such things as “But surely A ought to do such and such,” or “Plainly it is morally permissible for B to do so and so,” and do not even try to prove that those judgments are true. Moreover, they often rest weight on the supposition that those judgments are true. In particular, they often rest theories on them: they take them as data.
Others object. They say that nobody is entitled to rest any weight at all on judgments such as those. They say, not that the judgments are false, but that there is no reason to believe them true. They say, more generally, that there is no reason to think of any moral judgment that it is true. I will call this The No Reason Thesis.
Is there reason to think The No Reason Thesis true? There are lots of arguments for it in the literature, but I want to focus on one of them in particular. I think that the one I will focus on lies behind all the others, but no matter if it does not: I suggest that if this argument fails, they all fail.