I simply do not understand the problem of universals, i.e. I don't understand how it is even a problem.

The IEP writes:

We can approach the question about the existence of universals from a linguistic perspective. Consider how often we speak of things having properties: “That apple is red;” “The oven is hot;” or “My shirt is dirty.” Such sentences have a subject-predicate structure. The subject term refers to the individual described in the sentence. The predicate, on the other hand, describes; it tells us something about the way that individual is, how it is qualified. Do predicates also refer? Some philosophers think they do. Alongside the individuals picked out by subject terms of sentences, it is thought, there are entities of a different kind, picked out by predicates. Once again we can call these “universals”.

Prima facie, there seems to be every reason to believe in universals.

Well, not for me.

I simply do not see how we gain anything by using universals.

It seems obvious to me that

"This apple and this ruby are both red because they share the universal redness." (1)

doesn't explain more than saying:

"This apple and this ruby are both red, because this apple is red and this ruby is red." (2)

Explanation must always come to an end. Formulation (2) ends by just stating the brute fact that the apple is red and the ruby is red.

What "This apple is red." and "This ruby is red." means isn't further explained, but I don't see this as a problem — it's not worse than formulation (1) which leaves us with the brute, unexplained entity "redness".

Now, why isn't it an alternative to always stop at the "fact-level"?

If I have an antique clock and teacup, which were both manufactured in the year 1816, they are obviously similar in the respect that they were manufactured both in the same year, 1816. We can also give this property a name, like eighteensixteen-y. But surely nobody would see the need to postulate an ultra-strange universal "produced-in-the-year-1816-ness" which they both share.

The similarity is explained by paraphrasing the brute fact:

"The clock and the teacup are eighteensixteen-y, because the clock was manufactured in 1816 and the teacup was manufactured in 1816."

and that's all there is to it.

How is the situation with the red apple and the red ruby really different?

  • (2), as worded, leaves unexplained how you can predicate redness of anything. To put it another way, one view of universals is that these are epistemic categories we put things in. That seems like a pretty big problem. A second problem is we can say two things are both red, meaning can we abstract from the red we see to a red we can compare or identify things with. Separately, If fact-level your term or did you find it somewhere?
    – virmaior
    Commented Aug 1, 2015 at 3:41
  • The first sentence isn't quite right; you've introduced a notion of causality in there that doesn't belong ie because. Commented Aug 1, 2015 at 12:12
  • 1
    It sounds like you are what they refer to as a nominalist. Nominalism only believe in particulars, they do not accept the existence of universals. The realist and nominalist debate has been around for sometime. Realists believe in both particulars and universals. Ignore the naming of the world view as "Realist/Realism" that is just simply how the view is commonly refered.
    – hellyale
    Commented Aug 1, 2015 at 21:18
  • More particularly, it sounds like he's a "naive nominalist" to coin a new term. Most nominalists do accept the existence of categories; they merely deny that these categories have any independent existence as forms/essences. He doesn't seem to recognize what he's doing in predication, i.e. invoking universals.
    – virmaior
    Commented Aug 2, 2015 at 23:21
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    Okay, now that I better understand your question I can try to give an answer.
    – virmaior
    Commented Aug 4, 2015 at 2:59

4 Answers 4


You speak in favor of facts. But what are facts?

I suppose that by 'facts' you mean true sentences. There is also a metaphysical sense of 'facts', as in Wittgenstein's Tractatus. But those "facts" are as metaphysically loaded as universals, so I don't suppose that you referred to them.

But what is a true sentence? What makes a sentence true? There are several theories as to that, but the most common answer is that a sentence is true if (and only if) it corresponds to the world. A sentence is true if it corresponds to the way things are.

But what is correspondence to the world? Well, we can begin like this. In a sentence like

This apple is red

The words "this apple" correspond to an actual physical apple, this apple.

Next, I'm not sure about the word 'is'. Not all the words in a sentence need correspond to the world. There may also be some "intra-linguistic" words, those that play only an language-internal role, and do not correspond to the outside world. 'Is' may be one of those words.

The word 'red', on the other hand, does not seem to be intra-linguistic. Surely it just corresponds to the vivid redness of the apple?

And that's a reason, why we require words like "redness" - to distance ourselves from the internals of language, to mark that we refer to something, not in here, but out there.

(The truth is out there)

  • Facts are just the way how the world is. I simply do not see a reason why there have to be things that make a sentences true. A sentence is made true by how the world is.
    – Ystar
    Commented Aug 2, 2015 at 14:12
  • I understand predication like "x is P" as something we may not be able to further analyze. There may be scientific, reductive explanations, but sometimes (e.g. if x = 'electron' and P = 'charged') it would just stop there. Explanations must always come to an end. If we postulate universals we stop at the question "How do universals do what they are supposed to do?", I don't see how this is better than stopping at the question "How can a predicate apply to a particular?" ?
    – Ystar
    Commented Aug 2, 2015 at 14:39
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    @Ystar In philosophy, explanations do not come to an end. We need, in principle, to answer all the questions. We just don't do it all at once. Commented Aug 2, 2015 at 16:52
  • But our minds are finite, so how can we handle an infinite chain of explanations?
    – Ystar
    Commented Aug 4, 2015 at 2:38
  • I don't think that the explanations form a chain. They interlock in mutual support, as in reflective equilibrium. Commented Aug 4, 2015 at 10:02

The problem of universals arises because we generally encounter things in the world under kinds and properties. As in, I go throughout the world and see apples, cans of coke, trees, people, yellow bananas, tall trees, square boxes, grey elephants, etc.

The problem of universals can be addressed in two ways, either we need to explain what these universal categories are or we need to explain away the way that our cognition works.

Realist Explanations

The two most famous classical Western accounts provided related but different explanations, with Plato positing the forms/ideas (from a separate world) and Aristotle essences/forms (in natural things as their organizing principles). This manner of thinking was echoed in Augustine and Aquinas.

Modifying your (1):

Plato: "This apple and this ruby are both red because they participate in the form of red." (1')

(though my memory seems to indicate there's a problem with colors as forms for Plato but we'll ignore that).

Aristotle: "I intuit that that this apple and ruby both have redness." (1'')

(though for Aristotle redness is not an essence)

Traditional Nominalist Explanations

But later medieval thinkers like John Duns Scotus and John Buridan shifted to views we call "nominalism." They thought that the answers to how these sort of predications work are in the names of things and in our minds rather than in things or off in a Platonic heaven. For the most part, though, it's not that they deny a category of man that exists in the mind, but rather that they deny that the category has a necessary existence founded outside the mind.

These views do not postulate a thing for the universal -- they take it to be a concept in our minds (addressing part of your concern in a comment)

Medieval nominalists: "This apple and this ruby both fit with the word/concept red that I use to predicate" (1''')


""This apple and this ruby are both red, because this apple fits under the predication of the name/concept red and this ruby fits under the predication of name/concept red." (2')

(where predication is understood as the mental activity of applying names to things).

(There are of course people who denied there were existing essences both in the West in some forms of skepticism [elsewhere too] and in the East).

Descartes too has a philosophy that depends on the nature of ideas in our head but takes these ideas to have an origin outside the mind (think for instance of his argument for God's existence in Meditation 3 which hinges on the origin of the idea of infinity and thus has both ontological and cosmological elements).

The Problem with Universals

There's all sorts of problems with universals, a problem noted as far back as Plato's Parmendies and what Aristotle called the third man argument where forms multiply endless. There's also a problem of where forms come from -- in Plato's case, they are all stored up in an unchanging "heaven." In Aristotle's case, the essences wind up being interlinked with an argument for the immortality of the soul.

The Problem with Explaining Away Universals

In response to the problems with universals, several philosophers in the logical positivism / philosophy of language stream have as you noted taken up views like "predicate nominalism." These views attempt to explain away universals. But this is done at a cost, viz., as you note you have to make predicating "unanalyzable and primitive."

While this gets you out of explaining how universals work, you've now asserted we cannot explain what we do when we predicate. I called this "naive nominalism" for two reasons. First, insofar as we've lost the mental apparatus that the earlier nominalists used to explain how we predicate. Second, this is a mirror of what Hegel calls "sense certainty," the view that truth is just what I see when I see it.

In this case, the problem of predication would be justifying why we've given up on explaining predication but still think it's somehow meaningful. To make this move work, you're going to need a pretty substantial defense of the claim that predication is unanalyzable that still allows us to (a) make negative predications and (b) allows us to predicate of multiple things.

You ask:

Why can't we use the predicate 'red' without it and take it as unanalyzable, primitive? "The apple is red." just describes how the apple is.

You seem to be saying we cannot know what we mean when we call the apple red. That strikes me as quite strange. I think we mean that an apple has a certain color. Or more generally, it sounds like we are asserting some object has some property. But you're telling us we are doing something we cannot understand.

A second related issue might make it clearer. It seems we can also make negative predications: the apple is not green. But is this too to be seen as unanalyzable? If so, how? It seems we are saying, this apple does not fit with this property.

When you state (2),

"This apple and this ruby are both red, because this apple is red and this ruby is red." (2)

The problem here is that if [this apple is red] and [this ruby is red] are unanalyzable predications, then it's not clear how we can break the [] and take the word red and apply it to both. Maybe, you're saying we cannot.

If so, then you're saying we cannot compare things, which seems a long way to go to avoid every possible formulation of universals. If you're saying we can, then what is the red that's detachable from particular predications in this way?

A third possibility is you're saying that the "is" of predication is difficult. And it is. But then that seems to revive the problem of universals, and to just be saying that's hard to know what these predicates we seem to work with are.

To sum up, if you're trying to avoid "universals" to avoid an overly complex metaphysical world, that's an admirable goal. But not all views that include "universals" are committed to saying they are independently existing entities, and if you have to say we cannot analyze predication avoid them, then that invites some pretty deep problems of its own.

Another issue that you raise is the types of predicates. I haven't addressed that very directly (only by mentioning that Plato and Aristotle deeply limit the number of entities they are dealing with or at least notice the problem), but clearly there are nonsense predicates (made-in-1816-ness) that no one grants are universals. We needn't say anything about whether there are any things like universals inside or outside of minds to avoid these.

  • I wouldn't say that we can't say what we mean when we call an apple red — of course we can try to describe scientifically, e.g. that light gets reflected in a certain way (again, that's what I meant with 'facts'). But it would be primitive and unanalyzable on a metaphysical level. If we compare particulars, like in "this apple and this ruby are both red", we state that they resemble each other and the predicate 'red' tells us how they resemble each other.
    – Ystar
    Commented Aug 8, 2015 at 3:23
  • I find it surprising that you think 'eighteensixteen-y' is a nonsense predicate. If 'eighteensixteen-y' is applied to a particular, it tells you something about that particular. You don't want to grant an universal for this predicate — but why is postulating an universal preposterous to explain "This clock and this teacup are both eighteensixteen-y." but necessary to explain "This apple and this ruby are both red."?
    – Ystar
    Commented Aug 8, 2015 at 3:25
  • While I do it too sometimes, italicizing doesn't actually add meaning and in this case its revealing. I don't follow how something can be understandable in a normal sense but "primitive unanalzyable on a metaphysical level." That would mean our metaphysics is less capable of cutting the world at its joints than making no such effort.
    – virmaior
    Commented Aug 8, 2015 at 14:42
  • Regarding your second point in your first comment, no one disagrees that calling both red indicates that this is (at least one way) how they resemble each other. But we don't need to see both to know they are similar, because we are able to do compare them through the idea of the predicate. Do you honestly need to see two red objects simultaneously to know both are red? Otherwise, you seem to be able to abstract the color and work with that concept and then apply it elsewhere which would be something other than primitive and unanalyzable predication.
    – virmaior
    Commented Aug 8, 2015 at 14:57
  • In terms of 'eighteensixteen-y' as a bit of a nonsense predicate (vis-a-vis) universals, my simplest answer is that while it may be a fact about an an objects, it's not a fact of the object in a constitutive way, meaning you need to (in general) know the narrative history of the object to attribute that. This means it's going to be really complex to work with, and it's doubtful that forms a category in most people's minds (maybe a coin collector would have a concept of this as they think of objects).
    – virmaior
    Commented Aug 8, 2015 at 14:59

I simply do not see how we gain anything by using universals.

This sounds very pragmatist.

Realism (in the sense of acceptance of universals) says there are predicates which are not simply invented by man but which truly exist in the things predicated.

C. S. Peirce,* who defines "fact" as "an element of truth expressible as a proposition," defines nominalism vs. realism very well (CP 1.27 fn):

It must not be imagined that any notable realist of the thirteenth or fourteenth century took the ground that any “universal” was what we in English should call a “thing,” as it seems that, in an earlier age, some realists and some nominalists, too, had done…. [The "notable realist"s'] very definition of a “universal” admits that it is of the same generic nature as a word… Neither was it their doctrine that any “universal” itself is real. They might, indeed, some of them, think so; but their realism did not consist in that opinion, but in holding that what the word signifies, in contradistinction to what it can be truly said of, is real. Anybody may happen to opine that “the” is a real English word; but that will not constitute him a realist. But if he thinks that, whether the word “hard” itself be real or not, the property, the character, the predicate, hardness, is not invented by men, as the word is, but is really and truly in the hard things and is one in them all, as a description of habit, disposition, or behavior, then he is a realist.

*(He called, in CP 1.15, almost all philosophers since Descartes nominalists, i.e., deniers of universals)


(1) and (2) are different in this way :

In (1) the apple and ruby would be the same shade of red.

In (2) the apple and ruby could be different shades of red.

Although in sentence (1) should be slightly reworded to "a universal redness" rather then "the universal redness".

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