In this book, Aladdin M. Yaqub describes a simple conception of truth and shows that it yields a semantical theory that accommodates the whole range of our seemingly conflicting intuitions about truth. Yaqub's conception takes the Tarskian biconditionals (such as "The sentence 'Johannes loved Clara' is true if and only if Johannes loved Clara") as correctly and completely defining the notion of truth. The semantical theory, which is called the revision theory, that emerges from this conception paints a metaphysical picture of truth as a property whose applicability is given by a revision process rather than by a fixed extension. The main advantage of this revision process is its ability to explain why truth seems in many cases almost redundant, in others substantial, and yet in others paradoxical (as in the famous Liar). Yaqub offers a comprehensive defense of the revision theory of truth by developing consistent and adequate formal semantics for languages in which all sorts of problematic sentences (Liar and company) can be constructed. He also gives a detailed critical exposition of the proposals of Herzberger, Gupta, and Belnap. Yaqub concludes by introducing a logic of truth that further demonstrates the adequacy of the revision theory. The Liar Speaks the Truth starts with a basic and intuitive understanding of the notion of truth and ends with a complex logic of truth. The book will interest students of logic, truth theory, formal semantics, and philosophy of language.

Centuries after his death, al-Ghazali remains one of the most influential figures of the Islamic intellectual tradition. Although he is best known for his Incoherence of the Philosophers, Moderation in Belief is his most profound work of philosophical theology. In it, he offers what scholars consider to be the best defense of the Ash'arite school of Islamic theology that gained acceptance within orthodox Sunni theology in the twelfth century, though he also diverges from Ash'arism with his more rationalist approach to the Quran. Together with The Incoherence of the Philosophers, Moderation in Belief informs many subsequent theological debates, and its influence extends beyond the Islamic tradition, informing broader questions within Western philosophical and theological thought. The first complete English-language edition of Moderation in Belief, this new annotated translation by Aladdin M. Yaqub draws on the most esteemed critical editions of the Arabic texts and offers detailed commentary that analyzes and reconstructs the arguments found in the work's four treatises. Explanations of the historical and intellectual background of the texts also enable readers with a limited knowledge of classical Arabic to fully explore al-Ghazali and this foundational text for the first time. With the recent resurgence of interest in Islamic philosophy and the conflict between philosophy and religion, this new translation will be a welcome addition to the scholarship.

This book reclaims logic as a branch of philosophy, offering a self-contained and complete introduction to the three traditional systems of classical logic and the philosophical issues that surround those systems. The exposition is lucid, clear, and engaging. Practical methods are favoured over the traditional, and creative approaches over the merely mechanical. The author's guiding principle is to introduce classical logic in an intellectually honest way, and not to shy away from difficulties and controversies where they arise. Relevant philosophical issues, such as the relation between the meaning and the referent of a proper name, logical versus metaphysical possibility, and the conceptual content of an expression, are discussed throughout. In this way, the book is not only an introduction to the three main systems of classical logic, but also an introduction to the philosophy of classical logic.

An Introduction to Metalogic is a uniquely accessible introduction to the metatheory of first-order predicate logic. No background knowledge of logic is presupposed, as the book is entirely self-contained and clearly defines all of the technical terms it employs. Yaqub begins with an introduction to predicate logic, and ends with detailed outlines of the proofs of the incompleteness, undecidability and indefinability theorems. Many other topics are covered: expressive completeness, the basics of set theory, infinite cardinalities, Cantor's Theorems, the Soundness and Completeness Theorems, Turing machines, the Halting Problem, predicate logic theories and their properties, elementary equivalence, isomorphism, Peano Arithmetic, second-order predicate logic and more.