The term 'Philosopher Known for His 'RAZOR'' can be summarized by two crossword solutions: OCCAM (5 letters) and WILLIAMOFOCKHAM (15 letters). OCCAM is a reference to the 14th century English philosopher William of Ockham, who is best known for his principle of parsimony, also known as Occam's RAZOR. This principle states that the simplest explanation is usually the correct one. William of Ockham was a Franciscan friar and theologian who wrote extensively on logic, philosophy, and theology. He is considered one of the most important medieval thinkers and his works have had a lasting influence on modern thought.