Steffen Koch

The traditional epistemological approach towards judgments like BACHELORS ARE UNMARRIED or ALL KNOWLEDGE IS TRUE is that they are justified or known on the basis of understanding alone. In this paper, I develop an understanding-based account which takes understanding to be a sufficient source of epistemic justification for the relevant judgments. Understanding-based accounts face the problem of the rational revisability of almost all human judgments. Williamson has recently developed a reinforced version of this problem: the challenge from expert revisability. This is the problem that even the best candidate judgments for understanding-based justification can be rationally rejected by the relevant experts, who may not even have any disposition or inclination to accept these judgments. However, I argue that expert revisability is fully compatible with the proposed understanding-based epistemology, because expert revisability is true of sufficient sources of epistemic justification in general. A remaining metaphysical worry is that understanding might end up being ‘too thin’ to play the envisaged epistemological role. This worry can be countered with a novel metaphysics of understanding involving second-order dispositions.

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.

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.