Lev Semyonovich Vygotsky (Russian: Лев Семёнович Выго́тский, IPA: [vɨˈɡotskʲɪj]; November 17 [O.S. November 5] 1896 – June 11, 1934) was a Soviet psychologist, the founder of an unfinished theory of human cultural and bio-social development commonly referred to as cultural-historical psychology, a prominent advocate for a new theory of consciousness, the "psychology of superman", and leader of the Vygotsky Circle (also referred to as "Vygotsky-Luria Circle").