Technologies are being developed for significantly altering the traits of existing persons (or fetuses or embryos) and of future persons via germ line modification. The availability of such technologies may affect our philosophical, legal, and everyday understandings of several important concepts, including that of personal identity. I consider whether the idea of personal identity requires reconstruction, revision or abandonment in the face of such possibilities of technological intervention into the nature and form of an individual's attributes. This requires an account of the work done by the concept of personal identity, and an explanation of what “conceptual impacts of technology” and “conceptual reconstruction” might mean.

Our existing notions of personal identity and related ideas such as personhood and autonomy may seem unable to comfortably accommodate the possibilities of technologically directed trait formation and development. This is a matter of moral and legal importance because the idea of personal identity embeds major values and reflects value-laden beliefs and attitudes. The assumed endurance of identity underlies interpersonal relationships, the assignment of rewards and punishments, and the very idea of what constitutes an autonomous person. Perhaps radical restructuring or even abandonment of concepts are sometimes called for when the world changes drastically, but I suggest that conceptual modification is not “compelled” for personal identity except under extreme circumstances—the remote possibility of rapid human “shape shifting” where physical and mentational attributes can be transformed quickly and continuously.

Efforts to enhance human traits, including merit attributes and other resource-attractive characteristics (e.g., intellectual and athletic aptitudes, physical size and appearance), may generate legal problems wherever the persistence of identity is presupposed. Some advance speculation is thus warranted on how trait change generally will be managed within our legal and socioeconomic systems, and more particularly on rights of access to trait-altering technologies. I mention the possible distributive effects of enhancing highly-resource attractive traits, including the strengthening individual powers to acquire still more increments in such traits in a self-reinforcing cycle. A brief review of some constitutional issues bearing on trait change completes the discussion.

I conclude that existing and projected technologies do not impel the abandonment or remodeling of the idea of personal identity. We may, however, have to reconsider some uses of this concept in different settings, to rethink our understandings of ideas of merit and desert, and to deal with the distribution of resources that may enlarge and entrench the “distances” between social and economic groups.