Mindreading is the capacity to attribute psychological states to others and to use those attributions to explain, predict, and understand others’ behaviors. In the past thirty years, mindreading has become the topic of substantial interdisciplinary research and theorizing, with philosophers, psychologists and, more recently, neuroscientists, all contributing to the debate about the nature of the neuropsychological mechanisms that constitute the capacity for mindreading. In this thesis I push this debate forward by using recent results from developmental psychology as the basis for critiques of two prominent views of mindreading. First, I argue that the developmental studies provide evidence of infant mindreading and therefore expose a flaw in José Bermúdez’s view that certain forms of mindreading require language possession. Second, I argue that the evidence of infant mindreading can also be used to undermine Alvin Goldman’s version of Simulation Theory.

My thesis tackles two related problems that have taken center stage in the recent literature on concepts: • What are the individuation conditions of concepts? Under what conditions is a concept C₁ the same concept as a concept C₂? • What are the possession conditions of concepts? What conditions must be satisfied for a thinker to have a concept C? I will develop a pluralist and contextualist theory of concept individuation and possession: different concepts have different individuation and possession conditions, and contextual factors play a crucial role in determining what concepts we attribute to other subjects when we ascribe propositional attitudes to them. In chapters 1-3, I defend a contextualist, non-Millian theory of propositional attitude ascriptions. Then, I suggest contextualist theories of ascriptions can be applied to the problem of concept individuation/possession. In particular, I use contextualism to provide a new, more effective argument for Fodor's “publicity principle”, according to which concepts must be shared in order for interpersonally applicable psychological generalizations to be possible. Publicity has important implications: in particular, it is inconsistent with existing versions of holism, on which concepts cannot be shared by ordinary thinkers. Nonetheless, in chapters 4-5 I show how holism can still play an important role in our best theory of concepts. More specifically, I argue that the tradition of appealing to modes of presentation in order to give an account of “Frege cases” is in fact committed to holism. To develop a version of holism that will give a successful account of Frege cases without violating publicity, I suggest we should adopt my pluralist-contextualist picture: on that picture, the concepts involved in a Frege case will be holistically individuated and not public, while other concepts will be more coarsely individuated and widely shared. In chapter 6, I will develop this view further by contrasting it with other pluralist theories (Weiskopf) and with rival theories of concepts, such as the localist views defended by Peacocke, Rey and Jackson.