Beginning with Socrates and especially Plato, the “problem of universals” (called universalia by logicians of the Middle Ages) has plagued the history of thought to this day. But what was — or rather, what is — exactly this problem? Is there really a problem? I put this idea in my head that I need to devote myself to this problem, but the truth is that I still do not fully understand its importance. What I would like to be able to do is to convince a complete layman in philosophy that he should be interested in this problem. At the moment, I find that completely impossible. Below, I reproduce some definitions of the problem I found online just to start thinking about it. The road ahead will be arduous, so I’ll start slowly.
From the classical passage of Porphyry’s Introduction to Aristotle’s Categories — “Isagogé”:
“I shall avoid investigating whether genera and species do exist in themselves, or as mere notions of the intellect, or whether they have a corporeal, or incorporeal existence, or whether they have an existence separated from sensible things, or only in sensible things; it is quite a mystery which requires a more thorough investigation than the present one.”
From the New Advent Catholic Encyclopedia:
“The problem of universals is the problem of the correspondence of our intellectual concepts to things existing outside our intellect. Whereas external objects are determinate, individual, formally exclusive of all multiplicity, our concepts or mental representations offer us the realities independent of all particular determination; they are abstract and universal. The question, therefore, is to discover to what extent the concepts of the mind correspond to the things they represent; how the flower we conceive represents the flower existing in nature; in a word, whether our ideas are faithful and have an objective reality.”
From the Internet Encyclopedia of Philosophy:
“Universals are a class of mind-independent entities, usually contrasted with individuals (or socialled “particulars”), postulated to ground and explain relations of qualitative identity and resemblance among individuals. Individuals are said to be similar in virtue of sharing universals. An apple and a ruby are both red, for example, and their common redness results from sharing a universal. If they are both red at the same time, the universal, red, must be in two places at once. This makes universals quite different from individuals; and it makes them controversial. Whether universals are in fact required to explain relations of qualitative identity and resemblance among individuals has engaged metaphysicians for two thousand years.”
From Kelley L. Ross., Ph. D.:
“The matter at issue is that, on the one hand, the objects of experience are individual, particular, and concrete, while, on the other hand, the objects of thought, or most of the kinds of things that we know even about individuals, are general and abstract, i.e. universals. Thus, a house may be red, but there are many other red things, so redness is a general property, a universal. There are also many houses, and even kinds of houses, so the nature of being a house is general and universal also. Redness can also be conceived in the abstract, separate from any particular thing, but it cannot exist in experience except as a property of some particular thing and it cannot even be imagined except with some other minimal properties, e.g. extension. Abstraction is especially conspicuous in mathematics, where numbers, geometrical shapes, and equations are studied in complete separation from experience. The question that may be asked, then, is how it is that general kinds and properties or abstract objects are related to the world, how they exist in or in relation to individual objects, and how it is that we know them when experience only seems to reveal individual, concrete things.”
I am sure I would never have thought about this problem by myself. I would accept that we are capable of abstractions and that’s it. Actually, I guess I still think so. Deep inside I think I am interested in this problem precisely because I do not see any problem, even though it has been so important throughout history. I have the feeling that it is only when I really see this problem that I will have the slightest chance of becoming a true philosopher someday.