In his main work, "The Logic of Scientific Discovery," Karl Popper presents epistemology as a methodology that explains why our knowledge is fallible and why we learn primarily from failed expectations rather than fulfilled ones. Knowledge advancement results from trial and error. The most significant outcomes of the book are the criterion of falsifiability for distinguishing scientific statements and Popper's proposal to solve the problem of the empirical basis of science. Popper's book is among the most important contemporary works in the field of the logic of science. It will provoke both agreement and dissent.