Abstract

In this paper I present a variant of the “Sleeping Beauty” case that shows that the “halfer” approach to the original Sleeping Beauty problem is incompatible with an extremely plausible principle pertaining to cases of disagreement. This principle says that, in “nonpermissive” contexts, the weight you give to a disputant’s view ought to be proportional to your estimation of the strength of the disputant’s epistemic position with respect to the disputed proposition. In requiring such proportionality, the principle denies the possibility of what I will call “robustly perspectival” contexts. Given the plausibility and widespread acceptance of this principle, its incompatibility with the halfer approach to Sleeping Beauty gives us an apparently powerful new argument against the halfer position and for the alternative “thirder” view. But I am a halfer, not a thirder. So I go on to argue that despite the principle’s intuitive plausibility, there are good reasons for thinking that the case presented here does involve a robustly perspectival context and that the principle should be rejected. I suggest that the lesson that we should draw from this case is not that we should accept the thirder view, but rather that rationality can be perspectival in a robust way that many may find quite surprising.