This thesis comprises three main chapters—each comprising one relatively standalone paper. The unifying theme is fragmentalism about truth, which is the view that the predicate “true” either expresses distinct concepts or expresses distinct properties. -/- In Chapter 1, I provide a formal development of alethic pluralism. Pluralism is the view that there are distinct truth properties associated with distinct domains of subject matter, where a truth property satisfies certain truth-characterizing principles. On behalf of pluralists, I propose an account of logic (...) and semantics that shows how they can answer central conceptual and logical challenges for their view. -/- In Chapter 2, I motivate and develop a modal account of propositions on the basis of an iterative conception of propositions, where the modality is logico-mathematical. The modal account of propositions takes the conception to motivate an inherently potential hierarchy of propositions. I show that the account helps provide satisfying solutions to the intensional paradoxes of Russell-Myhill, Kaplan, and Prior. -/- In Chapter 3, I propose that “true” is polysemous. I suggest that “true” is initially polysemous between correspondence truth and disquotational truth, and further polysemous between the meanings corresponding to the subconcepts of the concept truth generated by the indefinite extensibility of that concept. I show that the proposal provides satisfying solutions to the semantic paradoxes. (shrink)

While holism and atomism are often treated as mutually exclusive approaches to semantic theory, the apparent tension between the two usually results from running together distinct levels of semantic explanation. In particular, there is no reason why one can’t combine an atomistic conception of what the semantic values of our words are (one’s “descriptive semantics”), with a holistic explanation of why they have those values (one’s “foundational semantics”). Most objections to holism can be shown to apply only to holistic version (...) of descriptive semantics, and do not tell against any sorts of holistic foundational semantics. As Davidson’s work will be used to illustrate, by clearly distinguishing foundational and descriptive semantics, one can capture the most appealing features of both holism and atomism. (shrink)

Theories of concepts and concept acquisition are mutually constraining. How we envisage concept acquisition depends both on what we take concepts to be and what skills we can employ to acquire them. I argue that Ned Block’s cognitivist approach to concept acquisition is not compatible with his vision of conceptual role semantics. If concepts are defined by their conceptual roles, then the acquisition of new concepts will change the conceptual roles of concepts employed in any form of hypothesis formation and (...) confirmation learning. This breaks the evidentiary link between the concepts acquired and the evidence used to justify its subsequent applications. As a consequence, conceptual role semantics cannot avail itself of cognitivist approaches to concept acquisition. Despite this, they may nevertheless explain the apparent rational nature of much concept acquisition. (shrink)

The theory of concepts advanced in the dissertation aims at accounting for a) how a concept makes successful practice possible, and b) how a scientific concept can be subject to rational change in the course of history. Traditional accounts in the philosophy of science have usually studied concepts in terms only of their reference; their concern is to establish a stability of reference in order to address the incommensurability problem. My discussion, in contrast, suggests that each scientific concept consists of (...) three components of content: 1) reference, 2) inferential role, and 3) the epistemic goal pursued with the concept's use. I argue that in the course of history a concept can change in any of these three components, and that change in one component—including change of reference—can be accounted for as being rational relative to other components, in particular a concept's epistemic goal.This semantic framework is applied to two cases from the history of biology: the homology concept as used in 19th and 20th century biology, and the gene concept as used in different parts of the 20th century. The homology case study argues that the advent of Darwinian evolutionary theory, despite introducing a new definition of homology, did not bring about a new homology concept (distinct from the pre-Darwinian concept) in the 19th century. Nowadays, however, distinct homology concepts are used in systematics/evolutionary biology, in evolutionary developmental biology, and in molecular biology. The emergence of these different homology concepts is explained as occurring in a rational fashion. The gene case study argues that conceptual progress occurred with the transition from the classical to the molecular gene concept, despite a change in reference. In the last two decades, change occurred internal to the molecular gene concept, so that nowadays this concept's usage and reference varies from context to context. I argue that this situation emerged rationally and that the current variation in usage and reference is conducive to biological practice.The dissertation uses ideas and methodological tools from the philosophy of mind and language, the philosophy of science, the history of science, and the psychology of concepts. (shrink)