Plural Logic

Alex Oliver and Timothy Smiley provide a natural point of entry to what for most readers will be a new subject. Plural logic deals with plural terms ("Whitehead and Russell," "Henry VIII's wives," "the real numbers," "they"), plural predicates ("surrounded the fort," "are prime," "are consistent," "imply"), and plural quantification ("some things," "any things"). Current logic is singularist: its terms stand for at most one thing. By contrast, the foundational thesis of this book is that a particular term may legitimately stand for several things at once; in other words, there is such a thing as genuinely plural denotation. The authors argue that plural phenomena need to be taken seriously and that the only viable response is to adopt a plural logic, a logic based on plural denotation. They expound a framework of ideas that includes the distinction between distributive and collective predicates, the theory of plural descriptions, multivalued functions, and lists. A formal system of plural logic is presented in three stages, before being applied to Cantorian set theory as an illustration.

Technicalities have been kept to a minimum, and anyone who is familiar with the classical predicate calculus should be able to follow it. The authors' approach is an attractive blend of no-nonsense argumentative directness and open-minded liberalism, and they convey the exciting and unexpected richness of their subject. Mathematicians and linguists, as well as logicians and philosophers, will find surprises in this book.

Alex Oliver read philosophy at Cambridge and Yale. After a Research Fellowship at Gonville and Caius College, Cambridge, he joined the Faculty of Philosophy where he is now a Professor. He was awarded a Leverhulme Major Research Fellowship and the Mind Association's Senior Research Fellowship for work in logic. He also has a strong interest in philosophy and public affairs, and is a Fellow of the Judge Business School.

Timothy Smiley studied logic and philosophy at the University of Fribourg in Switzerland in 1948, before reading mathematics at Cambridge. After service in the RAF and the Air Ministry he was called to the Bar at Gray's Inn, but opted to take up a Research Fellowship at Clare College, Cambridge. He became Senior Tutor of his College and was a University Lecturer in Philosophy before being elected as Knightbridge Professor in 1980.