This chapter considers the “no-person strategy” for justifying abortion. This strategy asserts that unborn human beings are not “persons” in a morally relevant sense due to a lack of exercisable psychological functions like consciousness. The chapter focuses on what is referred to as the functional view of persons according to which be in a person requires having exercisable psychological functions. The typical way to motivate psychological accounts of the person are by way of brain transplant thought experiments. The central critique of this chapter is the problem of underdetermination. It demonstrates that the intuitions elicited by brain transplant experiments can be accommodated by non-functional views of the person, such as hylomorphic or animalist accounts of the person. Therefore, these thought experiments do not exclusively support the functional view nor definitively establish when personhood begins. The chapter also critiques attempts to reify the “self” as a purely mental entity, arguing against its plausibility and highlighting the arbitrariness of drawing moral boundaries based on the exercise of consciousness.