In one of its traditional usages, the word "ethics' refers to a branch of philosophy in the same sense as the word "logic" refers to another. Calling ethics a branch of philosophy is traditionally meant to do something more specific than simply describe ethics as philosophical thinking about moral issues and about the phenomena of human life which we call ethical. A branch of philosophy is usually defined by stating its tasks and its main questions, and it is perhaps symptomatic of the nature of the philosophical problems about ethics that many writers have felt a need to redefine its subject matter and to offer their own statements of its tasks and main questions. Ethics seems to be a branch of philosophy which more than other branches tends to call itself into question.