Consider a universe of size 10×10×10. Let there be 10 identical looking apples and 10 identical looking rods in it.

Why do realists insist that not just 20 things exists but there also EXISTS something common between some of them?

The arguments I've seen are subject-predicate discourse, attribute agreement and abstract reference. These three arguments seem like different versions of the same thing: when we say "A1 and A2 are apples", we're using the word apple because there is something common between them and it makes no sense to say "apple" if that common thing doesn't exist.

Can't we then simply say there is this particular thing, this particular thing and so on? This ontology should be independent of humans right? Why isn't it that particulars exists and that's all there is to it. No more descriptions.

The background for my question is that these 20 objects can be combined into any number of classifications. Like I'll call things {A1,A2,..A10,R1} as gusas or {A1,R1,R2,..R10} as busas. Are these universals as well? These are simply made by me. Cuz this seems to imply that objectively there are almost all possible definitions/collections as universals.

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    Because if there is only this particular thing and that particular thing it is unclear how we manage to distinguish apples from rods. Whether one is a realist or not, they better have a story to tell about that, "that's all there is to it" will not cut it.
    – Conifold
    Commented Jan 14 at 7:46
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    The word "insist" implies that they ought to know better. It implies that you are not interested in actually hearing their side of the argument because you already know the right answer. Commented Jan 14 at 8:12
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    if "10 identical looking apples" exist, then (each of) "10", "identical", "looking", "apples" exist..and barely "inside" one of the 10!? ...so they are "common".
    – xerx593
    Commented Jan 14 at 9:03
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    See Plato: particulars can be judged to be similar because they share something. That's all. Commented Jan 14 at 10:58
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    @ScottRowe I've added a supplement to my answer re. independent
    – Rushi
    Commented Feb 19 at 11:37

4 Answers 4


It is all wordplay about the meaning of the word exist. If there are ten apples in the universe, then you can say numbers exist. If the apples have stalks, you can say stalks exist. If the apples are various shades of red and green you can say colours exist. You can say shapes exist. You can say positions and orientations exist, mass exists, etc etc. If there are ten rods too, you can say a combination of three apples and four rods exists, as does a combination of one apple and two rods, etc.

Clearly the apple has an existence that differs in character from the existence of the number seven, say- you would feel it if the apple collided with your head, which you cannot say about the number seven. If you would like to use a different word- axists, say- for abstractions such as numbers, so you might say that apples exist in the universe and numbers axist in the universe, then you are free to do so, but what value does that add?

'Apples' in this context refers to the ten things in the Universe that have apple-like characteristics, so you could go further and say that the ten apple-like things each exists and apples as a concept axists, but again you would have introduced a distinction that is more trouble than it is worth. I can just imagine the complications at the greengrocers...

Shopper: 'Are there any apples?'

Greengrocer: 'It depends what you mean, madam. I have existing objects of which each has the characteristics associated with the abstraction we know as 'apple', but I don't have any 'apples' per se, as you are referring to an abstraction.

Shopper: Do the existing objects also each have the properties associated with the abstraction we know as 'Granny Smith'?

Etc etc.

  • TIL: Philosophy = adults playing "Let's Pretend"
    – Scott Rowe
    Commented Feb 13 at 11:49

Can't we then simply say there is this particular thing, this particular thing and so on?

We sure can, but then we won't be able to communicate, thus defeating the whole purpose of language. When you say "that particular thing", how would I know what are you talking about (short of me seeing you pointing your finger at it)? Even you chose to go fully specific, saying "A2344-Y" -- a unique word you use to refer to that particular object -- it would still be just as meaningless to anyone else.

  • Yes, and, words are not things. Creating a word doesn't summon an entity from an eternal realm.
    – Scott Rowe
    Commented Feb 13 at 11:42
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    @ScottRowe -- exactly, I think words are just references to the ideas in our heads. We, as individuals, develop those universals -- universal ideas -- so we can understand each other. E.g. everyone of us developed an idea of an apple -- a universal encompassing this whole class of objects. In so doing we also learned its name -- "apple". And now whenever we hear or read that word we know what it means. Commented Feb 15 at 22:33

Does a stone block exist? (suppose your answer is yes; my answer is yes)

Does a bridge made of stone blocks exist? (suppose your answer here is also yes; my answer is yes)

In that case we must admit that arrangements of things that exist, also exist. But that is a level above the particulars, isn't it?

Suppose you say instead that a bridge made of stone blocks does not exist - only the blocks exist. Well, the blocks are made of bits of stone - we can further talk about atoms, neutrons, quarks. If you say nothing exists but the particulars, and that arrangements of particulars don't exist, aren't you committed to saying that only the lowest physical level exists: say, only the quarks exist? Only we don't know that quarks are the lowest level, so you are then consigned to being unable to name any object that you are confident exists. Is that manner of thinking appealing to you?

Let's say it is not appealing. So, we go back to saying that arrangements of things that exist also exist. The stone blocks exist and so does the bridge.

Well, in your universe, is the set of the ten apples not an arrangement of apples? And therefore, it exists. And so when we say that a certain object is an apple, we mean it is part of the set of apples, in the same way that we may say that a stone block is part of a certain bridge.

  • I would agree with you in using a meaning of 'exists' as: "it is the case". The bridge happens to be blocks arranged in a specific way at a particular time. But if you get too specific, then I could make a different bridge by swapping two of the blocks, which is absurd. We name things, including arrangements, but should not lose sight of the we that did the naming, or it is just silly.
    – Scott Rowe
    Commented Feb 13 at 11:46
  • While your point re. blocks n bridges is true, the Sorites Paradox is a more specialized problem. Denying universals implies denying concepts at their root — a much more radical axe to wield
    – Rushi
    Commented Feb 19 at 11:42

Thank you for your intriguing...

Thought Experiment

You posit:

Consider a universe of size 10×10×10. Let there be 10 identical apples and 10 identical rods in it.
Realists insist that not just 20 things exists but there also exists something common between some of them

How do you know that apples and rods exist unless there is prior experience of apple-ness and rod-ness?

You might protest that I am cheating by not quoting you exactly — you said 10 identical looking apples. I elided the looking. So to start with let me allay your fears — I cheated?? Yes... in a small way.

As we will soon see, you too are cheating and at a considerably larger scale. But before I come to that, let's clear up some misunderstandings/misfittings around your question

The same Einstein who constructed ingenious landmark thought experiments also cautioned: Make things as simple as possible and no simpler. The warning clause is crucial.

You have 'created' a 'universe' which does not contain you! How are you going to get any observations on it? So we must add you to your universe, or more generically, an observer. But we also need a vetter/verifier/auditor who can check and accept or reject your claims on/in this universe. [I'm assuming this is not a question on solipsism]

So then we have a universe with

  • 10 apple (looking) objects
  • 10 rod (looking) onjects
  • a subject S1 (you) who makes observations on this universe
  • another subject S2 who checks whether the first subjects observations and ratiocinations make sense

S1 presumably wants to communicate to S2 that there are only 20 entities (plus them) in the universe. And no such abstract entity such as 'apple(ness)' 'rod(ness)'.

Now if they can communicate this then they both have apple(ness) and rod(ness) in their minds.
If they cant then the experiment fails.


A prerequisite to the communication is the universal

But these are not the only universals that your own question is replete with:

  • The number 10
  • Hence number
  • The size (10×10×10 — though not sure why that's relevant)
  • Hence the '×' operation
  • Hence the general (notion of) operation

IOW not only would you not be able to vet your experiment without these (and many more) universals, you would not even be able to think your thoughts to yourself.

So to address your question in a more general setting: There would be no...

Fields of Endeavour

Every field of human endeavour has its own ontology. Eg. doctors think of people as patients or doctors or staff etc.
Airlines conceptualize in terms of passengers, place crew, airline staff, airport staff etc.

Any analyst who analyses and then designs a (computer) system for any of these, needs to start by identifying these core ontologies. Now you may say that all these are just the core idea of person from multiple different lenses.


There is a book: Mathsemantics by Edward MacNeal which deals with things like: How does an airline count the number of passengers.

In 1980 I was one passenger, ten passengers, eighteen passengers, thirty-six passengers, forty-two passengers, fifty-five passengers, seventy-two passengers and ninety-four passengers. Each of these statements is true.

He then goes on to explain.

I was one passenger in the sense that I was a person who traveled by air in that year. I was eighteen passengers in the sense that I made eighteen round trips. I was forty-two passengers in the sense that on forty-two different occasions I entered and exited the system of a different carrier. I was seventy-two passengers in the sense that on seventy-two occasions I was on board an aircraft when it took off from one place and landed at another. I was ninety-four passengers in the sense that I made ninety-four separate entrances and exits from airport terminal buildings.

[He missed the explanation for 10!]

I hope you appreciate that if the airlines, airports etc didn't keep these ontologies separate travel would be a mess at the least and probably quite dangerous

Sciences, Engineering

IOW for every field of science, engineering we need to start with a small but core set of ontologies that are assumed to be straightforwardly defined even if they are hard to pin down. Eg.

  • matter, energy in physics
  • points lines in geometry
  • etc

Aren't these what you call universals?

No Law

You would not be able to create the basic framework for law and order:

Citizen1: You cant beat your son!
Citizen2: You are free to not beat yours, I am free to beat mine
[IOW I reject any generic thing like son-ness ]

Note while the above conversation depends on the universal of son-ness, the conversation could not even start were it not for more primitive universals like 'yours' and 'mine' (ownership), citizenship etc.

No Concepts

In other words without universals, its not just specific fields of human endeavour that get compromised, the most basic presence of concepts themselves would not be possible.

No Language

You say you don't believe in God, yet you believe in grammar.


As with so much else, Nietzsche's understanding is truly awe-inspiring — language is really more fundamental than any notion of ultimate truth/reality we have even if we are committed theists. Because without it one would be able to even think a theistic or atheistic thought.

From a different perspective Wittgenstein too deeply understood this:

The limits of my language are the limits of my world

Lets just take two sentences from the first couple of paragraphs of your question:

Consider a universe...


The arguments I've seen are... Now flip around the articles; we get

The universe of size 10×10×10...
A(n) argument I've seen is...

In the second sentence the indefinite article 'a(n)' loses its punch when changed from 'the' — if you supply an argument which is unsatisfactory there could be others that are satisfactory.

And the first produces pure nonsense:

Assuming we all agree that something as unnoticed as articles cannot be misused without severe loss of semantics, we need to also admit that there is something universal and absolute in what these most basic words connote — definiteness, identity, multiplicity etc

From my point of view the language argument is more basic than all the above — because fields of human endeavour can be imagined to non-exist. Even logic has been around for some 2000 years.

But language defines what we are as humans — dunno how many million years — some beings like us have existed.

And language cannot exist without some universal commitment to (some) universals.

Clearly every abstract noun in our language is a universal. But common nouns, verbs etc are even more so though less noticeable.

And even as we've see the very basic constructions — articles. Likewise pronouns, conjunctions etc.

Its no exaggeration to say that every word in every language is a universal — except perhaps proper nouns

And all this on a factually incorrect basis

Finally the arguments against universals are made on a factually incorrect basis — if the ear is a concrete particular and hearing is an abstract universal, still there is a segment of the human brain — note I didn't say mind — corresponding to the hearing function.

And likewise its reasonable to assume that all the standard examples of universals eg. the color red, map similarly in your and my brain to neuronal connection patterns. Surely the brain areas (not mind) maps to faculty?

So the most basic argument against universals — that they don't exist in physical reality — is almost certainly untenable.

It's just that neuro-science is not yet up to affirming this in all its generality, but little by little its coming...

The Basic Fallacy

  • You define reality as empirical reality — reality is what is sense-able
  • You then tacitly define empirical reality as reality — since universals are not directly sense-able they are unreal

This is called a circular argument!

When you correct this to acknowledge that reality is a superset of empirical/sense-able reality, the corrected argument becomes:
Empirical-reality ⊆ Reality
∴ Universals ⊆ Reality / Empirical-Reality.

Added in response to comment

Scott Rowe: I think I would still assert that there is a difference between universals in our minds and having them exist independently, which I have always found incoherent. We create universals in our minds, that's what minds are for, largely. But we create lots of things in our minds. Would Plato say that debt actually exists, or that it is a game people play with numbers? Existence has gotten rather crowded, I can see why we need a multiverse to hold it all.

What does independent mean? Say we're having a conversation and in some context this snippet occurs:

R: ... red like an apple...
S: Where i come from, apples are bright green!
R: Aha! A Granny Smith man!
S: 😁.

Now if you acknowledge that such a conversation could happen it suggests that although you and I have never met, have not had the same experiences, have certainly never seen the same apples, yet our individual personal experiences of {red,green} are reasonably communicable. Of course the personal experiences may be nuancedly different, but they are also close enough that actual communication meaningfully happens.

In that sense qualia and universals are complementary views of the same truth — qualia emphasizes the individual differences and uniqueness. Universals focus on the common that is enough to make for a shared world experience.

Now switching to the traditional terminology for universals — Platonic forms or ideals.

Trouble is when teachers are talking Platonism 101, they give such extremally strawman presentations that it loses all meaning eg. Behind this chair there's a universal of chair-ness.

Now its simple enough to find/imagine human civilizations where chairs did not exist so this argument has no purchase.

But Plato was not talking of these 'strawman-universals' but of the essence of Beauty, Justice, Love... And most important of all Truth and The Good. The latter was the goal of philosophy, the former, all that could be empirically taught as the practice of philosophy.

Whereas these 'forms' were the real point, Plato evidently strongly believed that grappling with core math ontology eg. {point, line, number}... would serve as a good whetting and stepping stone towards Platonic philosophy. Because much more strongly than for {red, green}, one may assume that {lines, planes, numbers...} while having different associations for different individuals, had a sufficiently strong common core to serve as an exemplar for universals.

As to Debt, I guess its in a peciliar limbo between {point, line, number, ... Truth, Beauty,... Good} and {chairness}.

So while I agree with your instinct to apply Occam restriction on the Platonic world, What if we replace Debt by Gratitude?

Its also good to stop and wonder, If I reject Platonic forms/universals, what do I lose?

Heres an old question on the letter 'e'. You either accept that the letter 'e' is a coherent and therefore Platonic entity, or else lapse into absurd sophistry.

Unsurprisingly, Conifold seems to be the unique philosopher who chooses or at least hints at the sensible option!

  • After rereading your Answer, I think I would still assert that there is a difference between universals in our minds and having them exist independently, which I have always found incoherent. We create universals in our minds, that's what minds are for, largely. But we create lots of things in our minds. Would Plato say that debt actually exists, or that it is a game people play with numbers? Existence has gotten rather crowded, I can see why we need a multiverse to hold it all.
    – Scott Rowe
    Commented Feb 16 at 11:28
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    @ScottRowe since your question is pertinent and my answer too long for comments I've added it to the answer at end. Pls check!
    – Rushi
    Commented Feb 19 at 9:38
  • Ok, thank you. Math seems to be in general less fought over than social ideas like truth and the good. Math and gravity tend to punish fools reliably, but other fields allow the weeds to flourish. I think we simply need to bear in mind at all times that concepts are dangerous implements made by ourselves, like a stone tool with sharp sides that is just as likely to cut the user as the work. Handles on ideas, in a way, make them more treacherous for being able to be swung about indiscriminately. "Never give a sword to a man who can't dance."
    – Scott Rowe
    Commented Feb 19 at 12:33

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