Consequence is at the heart of logic, and an account of consequence offers a vital tool in the evaluation of arguments. This text presents what the authors term as 'logical pluralism' arguing that the notion of logical consequence doesn't pin down one deductive consequence relation; it allows for many of them.

Consequence is at the heart of logic; an account of consequence, of what follows from what, offers a vital tool in the evaluation of arguments. Since philosophy itself proceeds by way of argument and inference, a clear view of what logical consequence amounts to is of central importance to the whole discipline. In this book JC Beall and Greg Restall present and defend what thay call logical pluralism, arguing that the notion of logical consequence doesn't pin down one deductive consequence relation; it allows for many of them. In particular, they argue that broadly classical, intuitionistic, and relevant accounts of deductive logic are genuine logical consequence relations; we should not search for one true logic, since there are many. Their conclusions have profound implications for many linguists as well as for philosophers.

Logical pluralism is the view that different logics are equally appropriate, or equally correct. Logical relativism is a pluralism according to which validity and logical consequence are relative to something. In Varieties of Logic, Stewart Shapiro develops several ways in which one can be a pluralist or relativist about logic. One of these is an extended argument that words and phrases like "valid" and "logical consequence" are polysemous or, perhaps better, are cluster concepts. The notions can be sharpened in various ways. This explains away the "debates" in the literature between inferentialists and advocates of a truth-conditional, model-theoretic approach, and between those who advocate higher-order logic and those who insist that logic is first-order. A significant kind of pluralism flows from an orientation toward mathematics that emerged toward the end of the nineteenth century, and continues to dominate the field today. The theme is that consistency is the only legitimate criterion for a theory. Logical pluralism arises when one considers a number of interesting and important mathematical theories that invoke a non-classical logic, and are rendered inconsistent, and trivial, if classical logic is imposed. So validity is relative to a theory or structure. The perspective raises a host of important questions about meaning. The most significant of these concern the semantic content of logical terminology, words like 'or', 'not', and 'for all', as they occur in rigorous mathematical deduction. Does the intuitionistic 'not', for example, have the same meaning as its classical counterpart? Shapiro examines the major arguments on the issue, on both sides, and finds them all wanting. He then articulates and defends a thesis that the question of meaning-shift is itself context-sensitive and, indeed, interest-relative. He relates the issue to some prominent considerations concerning open texture, vagueness, and verbal disputes. Logic is ubiquitous. Whenever there is deductive reasoning, there is logic. So there are questions about logical pluralism that are analogous to standard questions about global relativism. The most pressing of these concerns foundational studies, wherein one compares theories, sometimes with different logics, and where one figures out what follows from what in a given logic. Shapiro shows that the issues are not problematic, and that is usually easy to keep track of the logic being used and the one mentioned.

This edited volume brings together 18 state-of-the art essays on pluralism about truth and logic. Parts I and II are dedicated to respectively truth pluralism and logical pluralism, and Part III to their interconnections. Some contributors challenge pluralism, arguing that the nature of truth or logic is uniform. The majority of contributors, however, defend pluralism, articulate novel versions of the view, or contribute to fundamental debates internal to the pluralist camp. The volume will be of interest to truth theorists and philosophers of logic, as well as philosophers interested in relativism, contextualism, metaphysics, philosophy of language, semantics, paradox, epistemology, or normativity.

For the past fifteen years, Aikin and Talisse have been working collaboratively on a new vision of American pragmatism, one which sees pragmatism as a living and developing philosophical idiom that originates in the work of the "classical" pragmatisms of Charles Peirce, William James, and John Dewey, uninterruptedly develops through the later 20th Century pragmatists (C. I. Lewis, Wilfrid Sellars, Nelson Goodman, W. V. O. Quine), and continues through the present day. According to Aikin and Talisse, pragmatism is fundamentally a metaphilosophical proposal – a methodological suggestion for carrying inquiry forward amidst ongoing deep disagreement over the aims, limitations, and possibilities of philosophy. This conception of pragmatism not only runs contrary to the dominant self-understanding among cotemporary philosophers who identify with the classical pragmatists, it also holds important implications for pragmatist philosophy. In particular, Aikin and Talisse show that their version of pragmatism involves distinctive claims about epistemic justification, moral disagreement, democratic citizenship, and the conduct of inquiry. The chapters combine detailed engagements with the history and development of pragmatism with original argumentation aimed at a philosophical audience beyond pragmatism.

This wide-ranging collection of essays explores the nature of logic and the key issues and debates in the metaphysics of logic.