The heuristic view of philosophy is opposed to the foundationalist view, according to which philosophy does not aim at knowledge and methods to acquire knowledge, but only at justifying already obtained knowledge, by providing a foundation for it. The foundationalist view assumes, first, that there is immediately justified knowledge and all other knowledge is deduced from it, and, secondly, that immediately justified knowledge is absolutely certain, being based on intuition. This chapter argues that both these assumptions are unjustified. One might think of replacing the foundationalist view with a milder version, the weak foundationalist view, according to which immediately justified knowledge, while not being absolutely certain, has at least some intrinsic credibility. But the chapter argues that the weak foundationalist view also is based on some unjustified assumptions.