Keynote

We are delighted to announce that the keynote talk, entitled 'The Ontology of Collectives', at this Symposium will be given by Professor Peter Simons from the Department of Philosophy, Trinity College Dublin, who is the author of the well-known and highly influential book Parts: A Study in Ontology (Oxford University Press 1987).

The Ontology of Collectives

Abstract

A collective is any entity which consists of more than one other entity, where "consists of" means the constituting entities are members rather than parts, so that a collective is in some way a plurality. Examples abound: families, forests, galaxies, clubs, teams, orchestras... the list goes on. Collectives come in many different kinds, and it is a job of ontology to propose the principles for their classification and for distinguishing them from other kinds of entity. We distinguish them here from individuals, masses, and institutions. In classifying them, two divisions cross. One is the division between extensional and non-extensional membership conditions. A collective is generally several entities such that ---, where the blank is filled by some condition spelling out what is required to be one of the collective. If several entities are not such that ---, they do not form a collective of the specific kind. If the same individuals fulfil more than on condition, they form distinct collectives, of different kinds. However if the condition is trivial or tautological, it is enough for the several entities in question simply to exist. In such a case the collective is nothing other than its several members, its identity conditions are extensional, and we call the collective a multitude. The other dimension of variation concerns whether a collective's members are individuals or not. A collective all of whose members are individuals may be called first-order; one whose members are individuals or first-order collectives, and which has at least one first-order member, is second-order, and so on. Higher-order collectives may include associations of clubs and societies. Admission of higher-order multitudes, pluralities of pluralities, opens an interesting possibility: a nominalistically acceptable substitute for set theory in providing the semantics for first- and higher-order logic.