The Presumptuous Philosopher and SIA in Anthropics
From the Wikipedia article on Problems with SIA: “One of the most prominent objections to SIA concerns Bostrom’s ‘presumptuous philosopher’ scenario. In this example, the non-anthropic evidence has led scientists to place equal credence on two rival cosmological theories T1 and T2. ‘According to T1 the world is very, very big but finite and there are a total of a trillion trillion observers in the cosmos. According to T2, the world is very, very, very big but finite and there are a trillion trillion trillion observers.’ Just as the scientists are preparing to run a cheap experiment that will definitively rule out one of the two theories, they are interrupted by a philosopher who believes SIA. He argues that the experiment is a waste of effort as T2 is a trillion times as likely to be true as T1. Bostrom finds this conclusion absurd and believes that it should thoroughly discredit SIA.” ...