  Poland recovered its independence in 1918 and Polish scholars began to build national academic life. The program for the development of mathematics elaborated by a mathematician Zygmunt Janiszewski (the Janiszewski program) had a great importance for the subsequent development of the LWS. According the Janiszewski program, Polish mathematicians should concentrate on set theory, topology and their applications to other branches of mathematics. In particular, the Janiszewski program attached great importance to mathematical logic and the foundations of mathematics. Two philosophers, namely Leśniewski and Łukasiewicz, became professors of the University of Warsaw at the Faculty of Mathematical and Natural Sciences. Both began intensive teaching of mathematical logic, mostly among mathematicians but also among philosophers. Thus, logic in the LWS had two parents: mathematics and philosophy.