INTRODUCTORY: REALISM AND NOMINALISM

The world appears full of repetitions, everywhere. The great variety in existence seems to be made out of the recurrence of a much less diversified plurality of constitutive principles: interpenetrating properties recombine in an indefinitely great multitude of ways, forming our physical universe of objects. Thus the world consists of a qualitative manifold, the elements of which exist in substantial concretions only, making objects the ultimate units of physical reality.

The repetitive aspect of the qualitative manifold involves much more than a mere recurrence of qualities themselves; spatial and temporal relations between substances and changes in them are to be cited as well. Moreover, another consequence of the repetitive aspect is the remarkable orderliness of the world. In compresences distributed through space, qualities form recurrent complex patterns: this is what we recognize as the diversity of kinds. Through time, on the other hand, patterns of succession manifest what we record as lawful regularities. If such ubiquitous repetition is an objective fact, the logical implication is that properties, relations and kinds apply multiply; they each exist simultaneously, in a great multiplicity of compresences. Each severally present existence is one and the same thing exemplifying itself in an indefinitely large number of objects. It is, in other words, an identity in a plurality, or what is called a ‘universal’. Accordingly, the property green is a universal, as it occurs both on this leaf and on that curtain, and every such occurrence is an instantiation or a token of that very same type.