EN
Sartre's philosophy is analyzed against the background of the philosophical tradition of the cogito. His contributions seem most impressive in the area covered by such concepts as the subject, consciousness, self-awareness, liberty, otherness and human responsibility. Although these topics seem to have attracted his undiminished attention all the time, one should be aware that his views on these matters gradually changed in his lifetime. In social questions his main interests shifted from the role of consciousness to the ontology of practical activity. In the philosophy of the individual they shifted from individual conscience to the appreciation of individual past experience. But despite these changes he consistently retained the structure of 'présence-a-soi', first, as a specific indication of human experience, and secondly, as an idea underlying being, history and philosophy. 'Présence-a-soi', and the manner in which its pragmatic aspect is introduced into phenomenology to explain the constitutive activity of the empirical consciousness are essential factors used in the explanation of socially widespread images, thoughts and practices that flourish without having a discernible author.