Abstract
According to the traditional analysis of knowledge, knowing that P requires being justified in believing that P. Since the justifier itself is required to be justified by another justifier whose justification needs further justifier and so on, this incurs the notorious problem of infinite regress of justification. BonJour, initially a representative defender of coherentism, claims that only foundationalism can solve the problem. The main purpose of this thesis is to examine (i) his criticisms of coherentism and externalism, and (ii) his arguments for his own version of foundationalism. I conclude that his critique of externalism in not well-founded and his foundationalism still cannot successfully solve the regress problem.