A presentation of current work that systematically explores and articulates the nature, origin and development of reasoning, this volume's primary aim is to describe and examine contemporary theory and research findings on the topic of deductive reasoning. Many contributors believe concepts such as "structure," "competence," and "mental logic" are necessary features for a complete understanding of reasoning. As the book emanates from a Jean Piaget Symposium, his theory of intellectual development as the standard contemporary treatment of deductive reasoning is used as the context in which the contributors elaborate on their own perceptions.

A presentation of current work that systematically explores and articulates the nature, origin and development of reasoning, this volume's primary aim is to describe and examine contemporary theory and research findings on the topic of deductive reasoning. Many contributors believe concepts such as "structure," "competence," and "mental logic" are necessary features for a complete understanding of reasoning. As the book emanates from a Jean Piaget Symposium, his theory of intellectual development as the standard contemporary treatment of deductive reasoning is used as the context in which the contributors elaborate on their own perceptions.

This is a reissue of a book which is an exploration and defence of the notion of modality 'de re', the idea that objects have both essential and accidental properties. It is one of the first full-length studies of the modalities to emerge from the debate to which Saul Kripke, David Lewis, Ruth Marcus and others have contributed. The argument is developed by means of the notion of possible worlds, and ranges over key problems including the nature of essence, trans-world identity, negative existential propositions, and the existence of unactual objects in other possible worlds. In the final chapters Professor Plantinga applies his logical theories to the clarification of two problems in the philosophy of religion - the Problem of Evil and the Ontological Argument.

Interest in the metaphysics and logic of possible worlds goes back at least as far as Aristotle, but few books address the history of these important concepts. This volume offers new essays on the theories about the logical modalities (necessity and possibility) held by leading philosophers from Aristotle in ancient Greece to Rudolf Carnap in the twentieth century. The story begins with an illuminating discussion of Aristotle's views on the connection between logic and metaphysics, continues through the Stoic and mediaeval (including Arabic) traditions, and then moves to the early modern period with particular attention to Locke and Leibniz. The views of Kant, Peirce, C. I. Lewis and Carnap complete the volume. Many of the essays illuminate the connection between the historical figures studied, and recent or current work in the philosophy of modality. The result is a rich and wide-ranging picture of the history of the logical modalities.

An argument that logic is intrinsically psychological and human psychology is intrinsically logical, and that the connection between human rationality and logic is both constitutive and mutual. In Rationality and Logic, Robert Hanna argues that logic is intrinsically psychological and that human psychology is intrinsically logical. He claims that logic is cognitively constructed by rational animals (including humans) and that rational animals are essentially logical animals. In order to do so, he defends the broadly Kantian thesis that all (and only) rational animals possess an innate cognitive "logic faculty." Hanna's claims challenge the conventional philosophical wisdom that sees logic as a fully formal or "topic-neutral" science irreconcilably separate from the species- or individual-specific focus of empirical psychology.Logic and psychology went their separate ways after attacks by Frege and Husserl on logical psychologism—the explanatory reduction of logic to empirical psychology. Hanna argues, however, that—despite the fact that logical psychologism is false—there is an essential link between logic and psychology. Rational human animals constitute the basic class of cognizers or thinkers studied by cognitive psychology; given the connection between rationality and logic that Hanna claims, it follows that the nature of logic is significantly revealed to us by cognitive psychology. Hanna's proposed "logical cognitivism" has two important consequences: the recognition by logically oriented philosophers that psychologists are their colleagues in the metadiscipline of cognitive science; and radical changes in cognitive science itself. Cognitive science, Hanna argues, is not at bottom a natural science; it is both an objective or truth-oriented science and a normative human science, as is logic itself.

Written in a clear, precise and user-friendly style, Logic as a Tool: A Guide to Formal Logical Reasoning is intended for undergraduates in both mathematics and computer science, and will guide them to learn, understand and master the use of classical logic as a tool for doing correct reasoning. It offers a systematic and precise exposition of classical logic with many examples and exercises, and only the necessary minimum of theory. The book explains the grammar, semantics and use of classical logical languages and teaches the reader how grasp the meaning and translate them to and from natural language. It illustrates with extensive examples the use of the most popular deductive systems -- axiomatic systems, semantic tableaux, natural deduction, and resolution -- for formalising and automating logical reasoning both on propositional and on first-order level, and provides the reader with technical skills needed for practical derivations in them. Systematic guidelines are offered on how to perform logically correct and well-structured reasoning using these deductive systems and the reasoning techniques that they employ. •Concise and systematic exposition, with semi-formal but rigorous treatment of the minimum necessary theory, amply illustrated with examples •Emphasis both on conceptual understanding and on developing practical skills •Solid and balanced coverage of syntactic, semantic, and deductive aspects of logic •Includes extensive sets of exercises, many of them provided with solutions or answers •Supplemented by a website including detailed slides, additional exercises and solutions For more information browse the book's website at: https://logicasatool.wordpress.com