Jylkkä, J. (2011). Hybrid Extensional Prototype Compositionality. Minds & Machines, 21, 41-56.

It has been argued that prototypes cannot compose, and that for this reason concepts cannot be prototypes (Osherson & Smith 1981; Fodor & Lepore 1996; Connolly, Fodor, & Gleitman 2007). In this paper I examine the intensional and extensional approaches to prototype compositionality, arguing that neither succeeds in their present formulations. I then propose a hybrid extensional theory of prototype compositionality, according to which the extension of a complex concept is determined as a function of what triggers its constituent prototypes. I argue that the theory escapes the problems traditionally raised against extensional theories of compositionality.


Jylkkä, J., Railo, H., & Haukioja, J. (2009). Psychological essentialism and semantic externalism: evidence for externalism in lay speakers' language use. Philosophical Psychology, 22, 37-60. (Non-citable PDF available here)

Abstract: Some experimental studies have recently claimed to undermine semantic externalism about natural kind terms. However, it is unclear how philosophical accounts of reference can be experimentally tested. We present two externalistic adaptations of psychological placeholder essentialism, a strict externalist and a hybrid externalist view, which are experimentally testable. We examine Braisby's et al. (1996) study which claims to undermine externalism, and argue that the study fails in its aims. We conducted two experiments, the results of which undermine internalism and the hybrid theory, and support strict externalism. Our conclusion is that lay speakers' natural kind concepts involve a belief in an external category essence, which determines reference.

Jylkkä, J. (2009). Why Fodor's theory of concepts fails. Minds & Machines, 19, 25-46. (Non-citable PDF available here)

Abstract: Fodor's theory of concepts holds that the psychological capacities, beliefs or intentions which determine how we use concepts do not determine reference. Instead, causal relations of a specific kind between properties and our dispositions to token a concept are claimed to do so. Fodor does admit that there needs to be some psychological mechanisms mediating the property - concept tokening relations, but argues that they are purely accidental for reference. In contrast, I argue that the actual mechanisms that sustain the reference determining concept tokening relations are necessary for reference. Fodor's atomism is thus undermined, since in order to refer with a concept it is necessary to possess some specific psychological capacities.

Jylkkä, J. (2008). Theories of natural kind term reference and empirical psychology. Philosophical Studies, 139, 153-169. (Non-citable PDF available here)

Abstract: In this paper I argue that the causal and description theories of natural kind term reference involve certain psychological elements. My main goal is to refine these theories with the help of empirical psychology of concepts, and to argue that the refinement process ultimately leads to the dissolution of boundaries between the two kinds of theories. However, neither the refined theories nor any other existing theories provide an adequate answer to the question of what makes natural kind terms rigid. To provide an answer to this question I conclude my paper by introducing a framework of a unified theory of natural kind term reference that is built on the empirical psychology of concepts.


Jylkkä, J. (2008). Concepts and Reference. Defending a Dual Theory of Natural Kind Concepts. Reports from the Department of Philosophy vol. 21. Turku, Finland: Painosalama.

Phd thesis, defended 22 November 2008 at the University of Turku, Finland. Inidividual articles included in the thesis are omitted in this online version, but they can be found independently above.