Ludwik Fleck (11 July 1896 – 5 June 1961) was a Polish and Israeli physician and biologist who did important work in epidemic typhus in Lwów, Poland, with Rudolf Weigl and in the 1930s developed the concepts of the "Denkstil" ("thought style") and the "Denkkollektiv" ("thought collective").
Read about Ludwik Fleck in Wikipedia