Analytical philosophy opens new perspectives of studies in the history of philosophy. There are generalized history of analytical interpretations of Cartesian principle cogito ergo sum and analysis of Cartesianism through the prism of contemporary philosophy of action, with special attention to performativity of the mentioned principle. The importance of such research necessarily goes beyond "pure" history of philosophy: it also contributes to revision of traditional approaches to justification of knowledge, which still remain problematic. Attention to performativism of cogito ergo sum (...) thesis is the key to new convenient interpretation of knowledge justification problem, because it allows for justification as selfjustification in terms of accomplishment. Inevitable accomplishment, peculiar to evidfently performative knowledge, suggests that fundamentalist strategy of knowledge justification, in the perspective of philosophy of action, amounts to a preferable interpretation compared to traditional epistemological approach. (shrink)