 Olaso’s work was not limited to the presence of skepticism in modern philosophy. He also devoted his efforts to interpret certain concepts of the main lexicon of skepticism. He was not only interested in skepticism from a historical point of view, but also from a philosophical perspective: he argued vigorously against the coherence of the skeptical position in “Zétesis” (Olaso 1988) a detailed paper on ancient Pyrrhonism, in which he displayed both an accurate understanding of this philosophical stance and a highly critical attitude toward the Pyrrhonian conception of investigation. His assessment of the concept of zétesis was very influential. Olaso interpreted it as an inquiry whose goal was suspension of judgment, which defined Pyrrhonism, and contrasted it to the open inquiry led by Academic and modern skeptics, whose goal is truth. Among his contributions, one finds also the distinction between the concept of doubt, or suspension of the mind, and the concept of epokhé, or suspension of judgment, which would be the proper attitude of a skeptic, because it is beyond doubt itself and tries to overcome it. These new interpretations were part of his debate with scholars like Naess, Chisholm, Mates, Frede and, of course, Porchat in order to find an acceptable form of contemporary skepticism. Based on Ortega y Gasset’s distinction between belief and knowledge, he proposed new accounts of Moore’s notions of common sense and certainty (Olaso 1975a) and the critical analysis carried out by Wittgenstein (Olaso 1999).