This book is a record of a seminar on mathematical logic Kurt G del and Hans Hahn held in Vienna in 1931-32. The seminar proceedings, given in English translation, are a unique witness of the state of research in logic and foundations of mathematics right after G del had published his celebrated incompleteness theorems. The seminars explain G del's results in logic in detail, in contrast to his publications of the time that often were quite laconic and extremely short. This book also contains G del's trial lecture on intuitionistic logic held in Vienna in 1933. The manuscript, recently found among the G del papers kept in Princeton, is preserved in G del's forgotten German shorthand and published here in an English translation.
The book also adds an important aspect to the intellectual history of Vienna, as both G del and Hahn were members of the Vienna Circle group of philosophers and scientists.