## Saturday, June 30, 2007

### No Credence

The end of a very wet June (not yet so weird as the butterflies last January though), but hopefully I'll be spending less time at the computer next month... Anyway, today (via TAR) I discovered Williamson's recent paper (in Analysis) in which he showed just how problematic is the assumption of regularity: that a credence (or subjective probability, or degree of belief, or of acceptance) of 1 implies absolute (not just everyday) certainty; that, conversely, if your credence in some proposition is 0 then you believe that it is impossible. But surely that assumption is clearly fallacious, like assuming that 0 length of a line means no part of a line, whereas points seem to be possible; so I'm wondering why it's so common: Is it something to do with the meaning of subjective probability?