Self is broadly defined as the essential qualities that make a person distinct from all others. The task in
philosophy is defining what these qualities are, and there have been a number of different approaches. The self is the idea of a unified being which is the source of an idiosyncratic
consciousness. Moreover, this self is the
agent responsible for the thoughts and actions of an individual to which they are ascribed. It is a
substance, which therefore endures through time; thus, the thoughts and actions at different moments of time may pertain to the same self (See John Locke's theory of consciousness as the basis of personal identity). As the notion of
subject, the "self" has been harshly criticized by Nietzsche at the end of the 19th century, on behalf of what
Gilles Deleuze would call a "becoming-other".
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