Martin Lin

Locke is often thought to have introduced the topic of personal identity into philosophy when, in the second edition of theEssay,he distinguished the person from both the human being and the soul. Each of these entities differs from the others with respect to their identity conditions, and so they must be ontologically distinct. In particular, Locke claimed, a person cannot survive total memory loss, although a human being or a soul can.

The Principle of Sufficient Reason is a powerful and controversial philosophical principle stipulating that everything must have a reason or cause. This simple demand for thoroughgoing intelligibility yields some of the boldest and most challenging theses in the history of metaphysics and epistemology. In this entry we begin with explaining the Principle, and then turn to the history of the debates around it. A section on recent discussions of the Principle will be added in the near future.