In order to decide whether particular enhancements compromise authenticity in the ways that these authors suggest, it is important to be clear about what kinds of things are the appropriate targets of attributions of authenticity. Do enhancements undermine the authenticity of one’s self, agency, achievements or actions? Authenticity is widely understood to be a matter of being “true to oneself”. Many authors in these debates do not take the time to carefully explicate their assumptions about “the self” and what it takes to be “true to” it. It is, of course, a challenge to characterize the self to which authentic individuals are true (Trilling, 1971; Taylor 1991; Guignon 2004). If there is a self, then there are difficult synchronic identification questions (i.e., at a given time, what features are constitutive of an agent?) and diachronic identification questions (i.e., across time, what features must persist in order for the self to survive?) that must be resolved. Derek Parfit, working in a tradition of “bundle theories of the self”, articulated the influential position that a person is nothing over and above a series of person-stages that are linked across time by certain psychological continuity relations (Parfit 1984). Given the controversy surrounding these debates about the nature of persons and personal identity, it is no surprise that there is little consensus about whether enhancements undermine authenticity of the self.