 What animalists reject is Locke’s claim that ‘person’ names a sortal concept (e.g., Snowdon 2014: ch. 3). Rather, following Olson (1997: ch. 2), most animalists insist that ‘person’ names only a phase sortal concept (or status concept, see Hacker 2007). (The idea of a “phased sortal”, as he called them, is due to Wiggins [1967, 2001].) Unlike a sortal concept, which determines the persistence conditions of its instances, a phase sortal concept is a concept to which its instances belong temporarily, for only a phase of their existence (e.g., teenager). Simply by reaching a particular age, for example, something that was not a teenager can become a teenager without ceasing to exist. Likewise, something that was a teenager can cease to be a teenager without ceasing to exist. So too, animalists say, with person. Personhood, they claim, is a phase that something begins upon acquiring the psychological capacities that Locke identifies (self-consciousness and rationality) and concludes upon losing those capacities. In this way, being a person is a matter of what something can do, rather than what something is. In Olson terminology, person is a “functional kind”, akin to locomotor (1997: 31–37). A locomotor is anything that is able to move about under its own power, be it a garden slug or a ballistic missile. Likewise, Olson argues (following Locke), a person is anything that is able to think in certain ways—anything that “is rational, … ordinarily conscious and aware of itself as tracing a path through time and space, … [and] morally accountable for its actions” (1997: 32). Many things besides human animals can be persons on this view: an angel, a god, a machine, an animal, an immaterial soul, an alien, etc.. In the case of human animals, we ordinarily become persons not at conception or at birth, but around the age of two. And while it is possible for a human animal to go out of existence at the same moment that she ceases to be a person (e.g., if she steps on an active landmine), it is also possible for a human animal to continue existing long after he has ceased to be a person (e.g., if he lapses into a persistent vegetative state).