Anthropic Bias explores how to reason when you suspect that your evidence is biased by 'observation selection effects'-that is, evidence that has been filtered by the precondition that there be some suitably positioned observer to 'have' the evidence. This conundrum-sometimes alluded to as 'the anthropic principle,' 'self-locating belief,' or 'indexical information'-turns out to be a surprisingly perplexing and intellectually stimulating challenge, one abounding with important implications fo