Alfred Tarski, one of the greatest logicians of all time, is widely thought of as "the man who defined truth". His work on the concepts of truth and logical consequence as defined by mathematical theory are cornerstones of modern logic, influencing developments in mathematics, philosophy, linguistics, and computer science. His teaching on logic and mathematics culminated in the 1941 classic INTRODUCTION TO LOGIC, which uses the method of deduction and explores logic and methodology as it pertains to creating mathematical theories. This is the original 1941 edition. DISCLAIMER: this version is based on a typeset scanned with editorial pen markings present which may be either distracting or insightful and helpful to some readers.