II. The Universal Concept, Formally Considered

1. The Universal in communi

1.1. Origin of the universal

The concepts of simple apprehension are conceived by a process of abstraction from sense knowledge. The justification of such a process and its analysis awaits us in the philosophy of knowledge, and not logic. For our discipline, it is important to show briefly the terminus a quo and the terminus ad quem of the completed process of abstraction.

In the beginning, our senses perceive an aspect of sensible data (such as color or figure, for example) synthesized into an interior image called the phantasm. This is always singular and material, like the image I make of Peter or of John when I think of them. At the end of the process of abstraction - which should not be thought of as abstracting some sort of residue! -, the intelligence reaches the level of reality present in the sensible data, but not known by the senses, and the quiddity or ratio of the perceived thing, which will always be universal and immaterial, like the concept of man.

So abstraction involves a passage from the essence realized in the singular individual to the common essence, which does not include the individuating aspects, as St Thomas explains:

And therefore it is proper to it to know a form existing individually in corporeal matter, but not as existing in this individual matter. But to know what is in individual matter, not as existing in such matter, is to abstract the form from individual matter which is represented by the phantasms. Therefore we must needs say that our intellect understands material things by abstracting from the phantasms;
I, 85, 1, c.


Et ideo proprium eius est cognoscere formam in materia quidem corporali individualiter existentem, non tamen prout est in tali materia. Cognoscere vero id quod est in materia individuali, non prout est in tali materia, est abstrahere formam a materia individuali, quam repraesentant phantasmata. Et ideo necesse est dicere quod intellectus noster intelligit materialia abstrahendo a phantasmatibus;
I, 85, 1, c.

By abstraction, the human intelligence knows the 'form' or quiddity of the individual thing, but not in an individual way, but rather a universal way, that is attributable to all the individuals which possess such an essence. In this way the notion of 'man' can be predicated of every concrete man, which truly express the essence. The universality is therefore a property of our concepts, following necessarily from abstraction.