Normative epistemology: the problem in perspective
A child does not need an epistemological theory. He learns with a relentless efficiency his adult incarnation will envy, but he makes no conscious use of explicit principles to guide or shape the runaway evolution of his world picture. For the most part, of course, neither does an adult. Upon being pressed for a justification or explanation of some conviction or epistemic decision, an adult may respond with the likes of ‘Well, such-and-such implies that P’, or P would explain so-and-so’, or ‘P is the only serious possibility I can think of’. But in the vast majority of cases such humble remarks exhaust the speaker's awareness of whatever principles we might assume to govern his intellectual evolution. And yet in adults as well as children that evolution displays a richness and complexity that explanations of the sort just cited barely begin to penetrate.
That complex evolution, therefore, wants accounting for, as it occurs both in infants and in adults. We wish to understand in detail the concert of factors that produce and shape it. So far, our concerns will be purely theoretical (descriptive, explanatory). But our concerns do not end here. In particular, we wish to understand what factors and principles guide intellectual development in a rational man, indeed, in an ideally rational man.