Occasionally, but not often, philosophers discover something genuinely new - a new problem or a subtle change in an old problem that brings a new set of issues into focus. When this happens circumstances are ripe for transformations not just of what we believe but also of what we think is worth considering and how we think we ought to proceed.

Beginning in the late 1960s something genuinely new happened in the centuries-old philosophical debate over personal identity; more precisely, something new would have happened, had it not happened once before, in the eighteenth century (this earlier discussion then was forgotten). What was new, on both occasions, is that tacit and extremely natural assumptions about the importance of identity in a person's so-called self-interested concern to survive were called into question. As a consequence, the traditional philosophical focus on metaphysics gave rise to new normative and empirical inquiries about what matters in survival. In these new inquiries fundamental and potentially unsettling questions were raised, for the first time (and as if for the first time), about the significance of the distinction between self and other.

The revolutionary and controversial thesis that identity is not what matters primarily in survival has been a principal focus of the more recent debate. The version of this idea that has gotten by far the most attention is the normative thesis that identity is not what should matter primarily in survival. This normative thesis has been endorsed by several influential philosophers.