Problem of the Priors

Canonical definition

The Problem of the Priors is the question of where an Individual's Prior over a set of Hypotheses comes from before Evidence bears on it, and whether that origin matters to the Belief the Individual reaches. Explanation. Two answers have been standard. One is a principle of indifference that spreads the Prior evenly over the Hypotheses, which gives different answers under different ways of dividing them. The other is a subjective Prior whose origin the Washing-Out Principle makes irrelevant once enough Evidence arrives. The architecture's answer is descriptive: most Priors are inherited. An Individual acquires Heuristics, and the Hypotheses that fill them, from other Individuals, so a population's Culture supplies the distribution its members begin from. Where the conditions of the Washing-Out Principle hold, the inherited Prior washes out. Where they fail, it persists. Where the true Hypothesis is absent from it, no quantity of Evidence supplies it, because a Hypothesis with no Prior receives no Posterior.