Deep selves, in one way or another, feature significantly within our folk-psychology and play a particularly central role in our moral responsibility practices. Our intuitions about others’ deep selves explain an otherwise complex pattern of responsibility attribution, with agents being held responsible for behaviour that in some way reflects the contents of their deep selves and getting off the hook for behaviour that doesn’t. Philosophers who have addressed the deep self concept directly have typically done so on the assumption that the object of these intuitions is a real thing - a natural psychological kind in the agents towards whom our deep self intuitions are directed. What I will put forward in this thesis is a challenge to this realist assumption and an alternative framing of the deep self as constituted by response-dependent properties. I begin by introducing the basic concepts: the deep self, attributability and a ‘Strawsonian reversal’ in the relationship between our reactive attitudes and the facts of moral responsibility. Chapter II is concerned with the principal philosophical accounts of the deep self and argues that none provides a viable account of response-independent properties capable of constituting the deep self as a natural kind. Chapter III is concerned with empirical investigations bearing both directly and indirectly on the deep self concept, proposing a cognitive account of deep self intuitions as products of our folk-psychology and causal reasoning. Chapter IV examines some of the practical implications of this model and presents arguments in favour of abandoning the realist assumption.