INTRODUCTION

D. M. Armstrong offers a theory of universals as the only adequate answer to a ‘compulsory question’ for systematic philosophy: the problem of One over Many. I find this line of argument unpersuasive. But I think there is more to be said for Armstrong's theory than he himself has said. For as I bear it in mind considering various topics in philosophy, I notice time and again that it offers solutions to my problems. Whatever we may think of the problem of One over Many, universals can earn their living doing other much-needed work.

I do not say that they are indispensable. The services they render could be matched using resources that are Nominalistic in letter, if perhaps not in spirit. But neither do I hold any presumptionagainst universals, to the effect that they are to be accepted only if we have no alternative. I therefore suspend judgement about universals themselves. I only insist that, one way or another, their work must be done.

I shall investigate the benefits of adding universals to my own usual ontology. That ontology, though Nominalistic, is in other respects generous. It consists of possibilia - particular, individual things, some of which comprise our actual world and others of which are unactualised - together with the iterative hierarchy of classes built up from them.