Ken Akiba

This book shows that the assumption that classical logic is essentially a bivalent (i.e., 2-valued) logic, a logic of truth and falsity, is an incorrect and harmful conception. Classical logic is certainly a Boolean logic, and the smallest (non-degenerate) Boolean algebra is the 2-element Boolean algebra; however, there are numerous Boolean algebras that have more than 2 elements, such as the 4-, 8-, 16-, ..., infinite-element Boolean algebra, and they all work equally well for the semantics of classical logic. Contrary to the popular thought, there is such a thing as classical (or Boolean) many-valued logic. The book applies this logic to solve such philosophical problems as the Fission Problem for personal identity, the Sorites Paradox, and the Liar Paradox. All these problems concern situations that involve indeterminacy or vagueness, situations where there seems 'no fact of the matter' that makes the relevant sentences true or false, thus requiring truth value gaps between truth and falsity. Because of that, classical logic has been thought to be an inadequate tool to deal with the problems. This book, however, offers solutions to those problems by retaining classical logic but assigning intermediate Boolean values to the relevant sentences. The book is of great value to researchers and graduate students in philosophy, especially for those who are interested in the philosophical issues surrounding indeterminacy, vagueness, and truth.

Many philosophy majors are shocked by the gap between the relative ease of lower-level philosophy courses and the difficulty of upper-division courses. This book serves as a necessary bridge to upper-level study in philosophy by offering rigorous but concise and accessible accounts of basic concepts and distinctions that are used throughout the discipline. It serves as a valuable advanced introduction to any undergraduate who is moving into upper-level courses in philosophy. While lower-level introductions to philosophy usually deal with popular topics accessible to the general student in a piecemeal fashion, The Philosophy Major's Introduction to Philosophy offers coverage of important general philosophical concepts, tools, and devices that may be used for a long time to come in various philosophical areas. The volume is helpfully divided between a focus on the relation between language and the world in the first three chapters and coverage of mental content in the final two chapters, but builds a coherent narrative from start to finish. It also provides ample study questions and helpful sign-posts throughout, making it a must-have for any student attempting to engage fully with the problems and arguments in philosophy. Key Features Integrates topics from various areas of philosophy, such as philosophy of language, metaphysics, epistemology, ethics, and philosophical logic Provides descriptions of logico-mathematical tools necessary for philosophical studies, such as propositional logic, predicate logic, modal logic, set theory, mereology, and mathematical functions Makes connections with modern philosophy, including discussions of Descartes's skepticism and dualism, Locke's theory of personal identity, Hume's theory of causation, and Kant's synthetic a priori. Includes well-known entertaining puzzles and thought experiments such as the Ship of Theseus, the Statue and the Clay, a Brain in a Vat, and Twin Earth Lists helpful Exercise Questions and Discussion Questions at the end of each chapter and answers selected questions at the back of the book.

This paper offers the Boolean many-valued solution to the Sorites Paradox. According to the precisification-based Boolean many-valued theory, from which this solution arises, sentences have not only two truth values, truth (or 1) and falsity (or 0), but many Boolean values between 0 and 1. The Boolean value of a sentence is identified with the set of precisifications in which the sentence is true. Unlike degrees fuzzy logic assigns to sentences, Boolean many values are not linearly but only partially ordered; so there are values that are incomparable. Despite this fact, the sentences in a sorites series can be taken as having values in a linear order, and losing (or gaining) value as we move from sentence to sentence in the series. So there is no sharp borderline between 0 and 1. Assigning Boolean many values instead of the two truth values to sentences for their vagueness values is analogous to assigning propositions instead of the truth values to sentences for their semantic values, as propositions are, from our viewpoint, also Boolean many values.

On the one hand, philosophers have presented numerous apparent examples of indeterminate individuation, i.e., examples in which two things are neither determinately identical nor determinately distinct. On the other hand, some have argued against even the coherence of the very idea of indeterminate individuation. This paper defends the possibility of indeterminate individuation against Evans’s argument and some other arguments. The Determinacy of Identity—the thesis that identical things are determinately identical—is distinguished from the Determinacy of Distinctness—the thesis that distinct things are determinately distinct. It is argued that while the first thesis holds universally and there is no case of indeterminate identity, there are reasons to think that the second thesis does not hold universally, and that there are cases of indeterminate distinctness.