Philisophical foundation of C. Wolff's principle of sufficient reason

Christian Wolff (1679-1757) was a 18th century philosopher of German enlightenment. This research reveals Wolff's philosophical approach to the principle of sufficient reason. It also shows why the principle is inevitable in order the knowledge to be based on. The principle of sufficient reason is classified from Leibniz on as an ontological principle and has gained its reputation from this. Wolff took this principle systematically and in detail and extended its content by adding it into psychology. The attachment of the principle of sufficient reason to psychology led to discussions about the problem of the free will. Thats why the question of free will in relation to this principle has been included to the research. Because the life, philosophy and literary works of Wolff has not been studied enough in Turkish sources these titles are included as well. Wolff isn't just important for the history of philosophy, but he also had an effect on the problems of the philosophy of religion. Therefore his views on revelation and deism, which are still contemporary problems of the philosophy of religon are incorporated into the research as much as it was needed.