  What could motivate alternative approaches to our identity, then, given the seeming successes of the Psychological Criterion? One important problem stems from worries about our essence. For instance, I am many things, including an adult, a professor, a driver, a voter, and so forth. None of these is my essence, however, for I either did or could exist without being them. If we could identify my essence, however (and generally the essence of individuals like me), we would be able to identify the conditions for my persistence across time as well. Now the Psychological Criterion seems to imply that personhood is my essence, that I couldn't exist without being a person, and given that personhood is a psychological matter, psychological continuity is what preserves my identity. But as Eric Olson and others have pointed out, this seems quite wrong (Olson 1997a, 1997b, DeGrazia 1999a, 1999b, Carter 1982, Snowdon 1990, Wiggins 1980). After all, just as I was once a teenager, and before that an adolescent and a child, wasn't I also an infant, and ultimately a fetus? Furthermore, suppose I were in a horrible accident and went into a permanent vegetative state (PVS). Wouldn't I then be in a PVS? If so, then if personhood necessarily involves having a certain sort of developed psychology (e.g., a psychology capable, at the least, of self-reflection), it can't be my essence; instead, being a person would be like being a child, or a teenager, something one becomes and may also outlive (called a “phase sortal” in the literature).