(1882-1936) German philosopher; founded logical positivists called Vienna Circle; wrote 1. Problems of Ethics and 2. Allgemeine Erkenntnisslehre . Rejected synthetic a priori knowledge. Viewed philosophy as
primarily logical analysis. Emphasized the analytical and a priori character of logic and mathematics. Distinguished empirical or factual from relational or logical knowledge. Limits knowledge to the empirical and the logical. Advocated a revised correspondence theory of truth (empirical realism).