Guido Löhr

An explanation of how we acquire concepts of kinds if they are socially constructed is a desideratum both for a successful account of concept acquisition and a successful account of social constructionism. Both face the so-called “mismatch problem” that is based on the observation that that there is often a mismatch between the descriptions proficient speakers associate with a word and the properties that its referents have in common. I argue that externalist theories of reference provide a plausible and attractive account of concept acquisition, including the acquisition of concepts of social constructs, that avoids the mismatch problem. However, externalist theories are ontologically and psychologically highly demanding, which places strong constraints on accounts of the metaphysics of socially constructed kinds. In particular, they require a rather strong form of realism that is incompatible with some but not all theories of social constructionism. Finally, I show that these demands can be met by means of adopting a homeostatic property cluster view of natural kinds.

Invariantists argue that the notion of concept in psychology should be reserved for knowledge that is retrieved in a context-insensitive manner. Contextualists argue that concepts are to be understood in terms of context-sensitive ad hoc constructions. I review the central empirical evidence for and against both views and show that their conclusions are based on a common mischaracterization of both theories. When the difference between contextualism and invariantism is properly understood, it becomes apparent that the way the question of stability is currently investigated will not lead to a consensus. Instead of focusing directly on stability, we should turn our attention to other desiderata on a theory of concepts. In particular, I show that invariantism, but not contextualism, fails to account for compositionality and abstract concepts.

Recent evidence suggests that participants without extensive training in philosophy (so-called lay people) have difficulties responding consistently when confronted with Robert Nozick’s Experience Machine thought experiment. For example, some of the participants who reject the experience machine for themselves would still advise a stranger to enter the machine permanently. This and similar findings have been interpreted as evidence for implicit biases that prevent lay people from making rational decisions about whether the experience machine is preferable to real life, which might have consequences for one of the strongest objections to philosophical hedonism (the view that pleasure is the only intrinsic value). Against this consequence, it has been argued that expert philosophers are immune to such biases (the so-called expertise defense). In this paper, I report empirical evidence against this expertise defense.

I discuss Edouard Machery’s claim that philosophers and psychologists when using the term ‘concept’ are really theorizing about different things. This view is not new, but it has never been developed or defended in detail. Once spelled out, we can see that Machery is right that the psychological literature uses a different notion of concept. However, Machery fails to acknowledge that the two notions are not only compatible but complementary. This fits more with the traditional view according to which philosophers and psychologists are merely interested in different aspects of the same kind. The main aim of this paper is then to show how precisely the two notions of ‘concept’ relate. Distinguishing them resolves the long-standing debate on whether concepts can be prototypes and allows me to formulate success conditions of a theory of categorization that are independent of the success conditions of a theory of concepts.