Jussi Jylkkä

Recent experimental studies have claimed to find evidence for the view that natural kind terms such as “water” are ambiguous: that they have two extensions, one determined by superficial properties, the other by underlying essence. In an online experiment, we presented to 600 participants scenarios describing discoveries of novel samples that differ in deep structure from samples of a familiar kind but are superficially identical, such as a water-like substance that is not composed of H2O. We used three different types of question sets to probe whether the participants considered the sample as a member of the kind or not. Our results did not confirm the predictions of the ambiguity view. They were, rather, consistent with views that take underlying essences to be the sole criterion for membership in a natural kind.

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, Franks, and Hampton's (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.

The typical empirical approach to studying consciousness holds that we can only observe the neural correlates of experiences, not the experiences themselves. In this paper we argue, in contrast, that experiences are concrete physical phenomena that can causally interact with other phenomena, including observers. Hence, experiences can be observed and scientifically modelled. We propose that the epistemic gap between an experience and a scientific model of its neural mechanisms stems from the fact that the model is merely a theoretical construct based on observations, and distinct from the concrete phenomenon it models, namely the experience itself. In this sense, there is a gap between any natural phenomenon and its scientific model. On this approach, a neuroscientific theory of the constitutive mechanisms of an experience is literally a model of the subjective experience itself. We argue that this metatheoretical framework provides a solid basis for the empirical study of consciousness.

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.

In this thesis I argue that the psychological study of concepts and categorisation, and the philosophical study of reference are deeply intertwined. I propose that semantic intuitions are a variety of categorisation judgements, determined by concepts, and that because of this, concepts determine reference. I defend a dual theory of natural kind concepts, according to which natural kind concepts have distinct semantic cores and non-semantic identification procedures. Drawing on psychological essentialism, I suggest that the cores consist of externalistic placeholder essence beliefs. The identification procedures, in turn, consist of prototypes, sets of exemplars, or possibly also theory-structured beliefs. I argue that the dual theory is motivated both by experimental data and theoretical considerations. The thesis consists of three interrelated articles. Article I examines philosophical causal and description theories of natural kind term reference, and argues that they involve, or need to involve, certain psychological elements. I propose a unified theory of natural kind term reference, built on the psychology of concepts. Article II presents two semantic adaptations of psychological essentialism, one of which is a strict externalistic Kripkean-Putnamian theory, while the other is a hybrid account, according to which natural kind terms are ambiguous between internalistic and externalistic senses. We present two experiments, the results of which support the strict externalistic theory. Article III examines Fodor’s influential atomistic theory of concepts, according to which no psychological capacities associated with concepts constitute them, or are necessary for reference. I argue, contra Fodor, that the psychological mechanisms are necessary for reference.

It has been argued that prototypes cannot compose, and that for this reason concepts cannot be prototypes (Osherson and Smith in Cognition 9:35–58, 1981; Fodor and Lepore in Cognition 58:253–270, 1996; Connolly et al. in Cognition 103:1–22, 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

Fodor’s theory of concepts holds that the psychological mechanisms which guide us in applying concepts to objects 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 mechanism mediating the property – concept tokening relations, but argues that it is purely accidental for reference. In contrast, I argue that the actual mechanisms that sustain the reference determining concept tokening relations are necessary for reference. Thus, to possess a concept it is necessary to possess some specific sustaining mechanism.

This paper argues that the epistemic gap in philosophy of mind stems from the fact that our awareness of our subjective experiences is categorically different from our knowledge of external phenomena. Our knowledge of external objects is always mediated through empirical observation or theoretical descriptions, and does not afford us knowledge of the intrinsic nature of the thing referred to, whereas our awareness of our experiences is immediate and affords us knowledge of the intrinsic nature of our experiences. Finally, it is argued that the thing itself referred to as “neural correlate of consciousness” is constituted by consciousness

Fodor’s theory of concepts holds that the psychological mechanisms which guide us in applying concepts to objects 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 mechanism mediating the property – concept tokening relations, but argues that it is purely accidental for reference. In contrast, I argue that the actual mechanisms that sustain the reference determining concept tokening relations are necessary for reference. Thus, to possess a concept it is necessary to possess some specific sustaining mechanism.

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. Ourconclusion is that lay speakers’ natural kind concepts involve a belief in an external category essence, which determines reference

The conceivability argument against materialism, originally raised by Saul Kripke and then reformulated, among others, by David Chalmers holds that we can conceive of the distinctness of a phenomenal state and its neural realiser, or, in Chalmers’ variation of the argument, a zombie world. Here I argue that both phenomenal and natural kind terms are ambiguous between two senses, phenomenal and natural, and that the conceivability argument goes through only on one reading of a term. Thus, the antimaterialist has to provide some reasons independent of anti-materialism itself to favour that reading of a term that supports his or her argument. Given that there are no such independent reasons, I conclude that we should put more weight on empirical considerations than on a priori discussion in resolving the question concerning the identity between a phenomenal state and its neural realiser

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.