Modality, rationalism, and conditionals

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, February 2007.Includes bibliographical references (leaves 105-108).This thesis consists of three interconnected papers on apriority, modality, and conditionals. In "Playground Conditionals," I look at three philosophical debates, each of which turns on the epistemic status of a certain kind of conditional-what I call a playground conditional. I argue that a close consideration of playground conditionals gives us a better appreciation of what we can do with conditionals and, ultimately, some guidance concerning what to say about the three philosophical debates. In "Modal Rationalism, Two Dimensionalism, and our Counteractual Sisters", I consider the prospects for modal rationalism in the wake of Kripke's Naming and Necessity. Recently there has been a modal rationalist revival, thanks in part to the development of the "two-dimensional" semantic framework. This framework associates two intensions (a primary intension and a secondary intension) with every sentence. The difficulty comes in finding a definition of primary and secondary intension that would lend the desired support to modal rationalism. After exploring and rejecting some of the proposed definitions in the literature, I sketch an account that can, I think, offer some support to a suitably framed modal rationalism.(cont.) Finally, in "A Guide to Modal Guidance," I set about to get clearer on how, exactly, we come to know modal truths. I start by considering two arguments that are designed to show that our access to modal knowledge cannot come from conceivability arguments. I show that, these arguments are mistaken. In the process, I attempt to outline a broader and more realistic modal epistemology than one that focuses exclusively on conceivability. I then consider and reject a version of modal rationalism which says that ideal conceivability gives us a priori access to modality. Against this, I argue that our modal knowledge is predominantly a posteriori, and that our knowledge of ideal conceivability is always a posteriori. In the end, however, I attempt to salvage something that preserves the spirit, if not the letter, of modal rationalism.by Jason Decker.Ph.D

Varieties of the transcendental : transcendental arguments and transcendental description

Transcendental claims offer necessary, universal, and a priori conditions for the possibility of various phenomena (cognition, perception, language etc.). The current discussion in epistemology takes transcendental arguments, specifically, to serve as refutations of skepticism. However, despite the critical intentions with which they are deployed, transcendental arguments run into problems centering on undeclared metaphysical presuppositions. The aim of this thesis is to challenge these dogmatic presuppositions and to liberate the transcendental from its narrow and problem-ridden focus in epistemology by turning to transcendental themes in the descriptive philosophies of Merleau-Ponty and Wittgenstein. While anti-skeptical transcendental accounts in epistemology are forced to posit strong and metaphysically charged conditions in order to refute the skeptic decisively, this thesis argues that Merleau-Ponty and Wittgenstein, by transforming the notions operative in transcendental claims – necessity, universality, and apriority – offer a non-metaphysical orientation for transcendental claims. In order to restore the critical impulse Kant once sought in transcendental considerations, this thesis details the basic elements of a pluralist and non-dogmatic transcendental perspective

Epistemic Modality, Mind, and Mathematics

This book concerns the foundations of epistemic modality. I examine the nature of epistemic modality, when the modal operator is interpreted as concerning both apriority and conceivability, as well as states of knowledge and belief. The book demonstrates how epistemic modality relates to the computational theory of mind; metaphysical modality; the types of mathematical modality; to the epistemic status of large cardinal axioms, undecidable propositions, and abstraction principles in the philosophy of mathematics; to the modal profile of rational intuition; and to the types of intention, when the latter is interpreted as a modal mental state. Chapter \textbf{2} argues for a novel type of expressivism based on the duality between the categories of coalgebras and algebras, and argues that the duality permits of the reconciliation between modal cognitivism and modal expressivism. Chapter \textbf{3} provides an abstraction principle for epistemic intensions. Chapter \textbf{4} advances a topic-sensitive two-dimensional truthmaker semantics, and provides three novel interpretations of the framework along with the epistemic and metasemantic. Chapter \textbf{5} applies the fixed points of the modal $\mu$-calculus in order to account for the iteration of epistemic states, by contrast to availing of modal axiom 4 (i.e. the KK principle). Chapter \textbf{6} advances a solution to the Julius Caesar problem based on Fine's "criterial" identity conditions which incorporate conditions on essentiality and grounding. Chapter \textbf{7} provides a ground-theoretic regimentation of the proposals in the metaphysics of consciousness and examines its bearing on the two-dimensional conceivability argument against physicalism. The topic-sensitive epistemic two-dimensional truthmaker semantics developed in chapter \textbf{4} is availed of in order for epistemic states to be a guide to metaphysical states in the hyperintensional setting. Chapter \textbf{8} examines the modal commitments of abstractionism, in particular necessitism, and epistemic modality and the epistemology of abstraction. Chapter \textbf{9} examines the modal profile of $\Omega$-logic in set theory. Chapter \textbf{10} examines the interaction between epistemic two-dimensional truthmaker semantics, epistemic set theory, and absolute decidability. Chapter \textbf{11} avails of modal coalgebraic automata to interpret the defining properties of indefinite extensibility, and avails of epistemic two-dimensional semantics in order to account for the interaction of the interpretational and objective modalities thereof. The hyperintensional, topic-sensitive epistemic two-dimensional truthmaker semantics developed in chapter \textbf{2} is applied in chapters \textbf{7}, \textbf{8}, \textbf{10}, and \textbf{11}. Chapter \textbf{12} provides a modal logic for rational intuition and provides four models of hyperintensional semantics. Chapter \textbf{13} examines modal responses to the alethic paradoxes. Chapter \textbf{14} examines, finally, the modal semantics for the different types of intention and the relation of the latter to evidential decision theory