Kučera was born in Třebařov (between Pardubice and Olomouc) in Czechoslovakia and later moved with his family to Hodonín, where he studied. When the Communists came to power in February 1948, his studies in philosophy and linguistics at Charles University in the Czech capital of Prague were interrupted. He was forced to leave Czechoslovakia in April 1948 when it became clear that his political writings had placed him at risk of detention by the Communist authorities.