LOGIC AND ONTOLOGY 1
The species of metaphysical speculation known as ontology is as old as philosophy itself. It is encountered in one form or another in all climes and times. In Western philosophy, it is already cultivated in a fairly sophisticated form in Parmenides: Being is positive and does not admit to the possibility of negation. Being is a plenum, etc. The problem which exercised the mind of Parmenides has lost something of its vitality in our time but it has recognizably survived in such contemporary questions as “Are there negative facts?” At the present day, however, the liveliest issues of ontology revolve round a topic which has a different, if no less celebrated, ancestry. It is the problem of universals which, much discussed by Plato, was taken up and made a principal concern by the scholastics. It is being canvassed again in recent times under the heading of abstract entities. What I wish to investigate is the connection between the metaphysics of abstract entities and the discipline of logic as developed in the modern era.