The author describes three steps of 20th century epistemology revealing contemporary science as oriented towards the future. The first methodological step she associates with K. Popper's falsifiability principle. The second step concerns with uncertainty as a characteristic of the subject of the "post-normal science". The third - with a change in the intention of contemporary science from the study of “what is”, to the search for “what may be and what may be different" or with an ontological turn.