Though no definition of philosophy is uncontroversial, and the field has historically expanded and changed depending upon what kinds of questions were interesting or relevant in a given era, it is generally agreed that philosophy is a method, rather than a set of claims, propositions, or theories. Its investigations are based upon reason, striving to make no unexamined assumptions and no leaps based on faith or pure analogy. Different philosophers have had differing ideas about the nature of reason, and there is also disagreement about the subject matter of philosophy. Some think that philosophy examines the process of inquiry itself. Others, that there are essentially philosophical propositions which it is the task of philosophy to prove. Although the word "philosophy" originates in the Western tradition, many figures in the history of other cultures have addressed similar topics in similar ways. The philosophers of the Far East are discussed in Eastern philosophy, while the philosophers of North Africa and the Near East, because of their strong interactions with Europe, are usually considered part of Western Philosophy.