Elga’s Highly Restricted Principle of Indifference

July 24, 2010

In the Sleeping Beauty paper, Elga tells us that “Since being in [Tails and Monday] is subjectively just like being in [Tails and Tuesday], and since exactly the same propositions are true whether you are in [Tails and Monday] or [Tails and Tuesday], even a highly restricted principle of indifference yields that you ought then to have equal credence in each”.

Recall that the unrestricted Principle of Indifference says that when your evidence doesn’t give you any more reason to believe one proposition rather than another, you should assign credence to the possibilities equally.

The more restricted principle Elga seems to be endorsing here is this:

Highly Restricted POI: If some collection of situations are subjectively identical and exactly the same uncentered propositions are true at them, one ought to divide one’s credences among them.

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