The subject

A subject is a being who has a unique consciousness and/or unique personal experiences, or an entity that has a relationship with another entity that exists outside of itself (called an "object"). A subject is an observer and an object is a thing observed. This concept is especially important in Continental philosophy, where 'the Subject' is a central term in debates over human autonomy and the nature of the self.

The sharp distinction between subject and object corresponds to the distinction, in the philosophy of René Descartes, between thought and extension. Descartes believed that thought (subjectivity) was the essence of the mind, and that extension (the occupation of space) was the essence of matter.

In the continental tradition, debates over the nature of the Subject play a role comparable to debates over personhood within the distinct Anglo-American tradition of analytical philosophy.

In critical theory and psychology, subjectivity is also the actions or discourses that produce individuals or 'I'—the 'I' is the subject.

Subject as a key-term in thinking about human consciousness began its career with the German Idealists, in response to David Hume's radical skepticism. The idealists' starting point was Hume's conclusion that there is nothing to the self over and above a big, fleeting bundle of perceptions. The next step was to ask how this undifferentiated bundle comes to be experienced as a unity – as a single subject. Hume had offered the following proposal:

Kant, Hegel and their successors sought to flesh out the process by which the subject is constituted out of the flow of sense impressions. Hegel, for example, stated in his Preface to the Phenomenology of Spirit that a subject is constituted by "the process of reflectively mediating itself with itself."

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