[Ludwik Fleck (1896-1961), bacteriologist and scientific theorist: science grows with collective thinking]

This is a short biography of the Polish-Ukrainian-Israelian bacteriologist and science theoretician Ludwik Fleck, whose life was marked by wars, years of captivity in concentration camps and changes of nationality. His most important insight into the way in which scientific knowledge is gained was that knowledge is not the result of an individual process of a theoretical consciousness by itself, but the result of collective social activity.