I understand the debate to be about whether abstract concepts actually "exist". As such, it is clearly an important question for ontology.

However, I fail to see any practical reason to care about this debate. Is there any scenario in which we would act differently, depending on whether we believe in Platonism or nominalism? Even nominalists will mostly agree that abstract concepts are useful, so not believing in their "existence" does not stop them from using those concepts in everyday life.

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    If generalized/abstract objects don't exist, then there are no general moral principles as such. Of course, one might posit general objects outside of ethics instead, but ruling out all such objects does decide in favor of moral particularism if anything thusly (I think). Sep 5, 2022 at 0:01
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    I do not think there is a single question in ontology with a "practical reason to care" in your sense. After all, whatever "truly" exists, tables would still be used for dining and bricks would still hit us on the head. It does not matter either if the quantum wave function is a physical entity or a fiction describing observer's knowledge since everybody agrees on how to calculate probabilities. So shut up and calculate. People do not function this way. Ontological debates disguise disagreements on how best to arrange our picture of the world, and affect decisions on where to go from there.
    – Conifold
    Sep 5, 2022 at 0:12
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    If you are not interested in philosophy and in some specific branch of it, there is no reason "to care about"... Sep 5, 2022 at 7:11
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    @MauroALLEGRANZA Perhaps they care about the results? I'm not a tool designer, but I use a hammer pretty often.
    – Scott Rowe
    Sep 5, 2022 at 13:50
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    Insofar as the ontology of spiritual experience you need some type of Platonism as discussed in detail by Sufism's lataif (white sirr) which are special organs of perception making up human's "subtle body": Kubrawi Sufi Simnani describes a dhikr practice that appears to include these lataif. The practice involves the rotation of attention and breath to different parts of the physical body... the lataif have their immediate historical antecedents in the Emanationism of Neoplatonism..., in turn, arose from the Theory of forms of Plato... Sep 5, 2022 at 20:53

2 Answers 2


You ask for a "practical reason", its not completely clear what a practical reason would look like. For example and by way of tenuous analogy (sorry physicists) is there a practical reason to care about theoretical physics as it stands today? In one sense, competing theories have enormous ramifications for the underlying structure of our universe, in another sense, it is unlikely that basic engineering principles -at least for 99.99 percent of objects that you and I use- will change. (perhaps a physicist will correct me).

The situation with abstracta is somewhat similar. A broad (and not completely accurate, although vaguely historical) picture in the philosophy of mathematics might be construed with platonists on one side and constructivists on the other. Now, the logic of constructivist and the platonist are different, and this would make a practical difference if you are a working mathematician, since one logic really is weaker than the other.

But more generally, people use abstracta dialetically. For example, people often have intuitions on where they fall in the abstracta debate. They can then use those intuitions to determine where they fall on other areas in which the abstracta debate plays some role, ie in philosophy of mathematics with numbers or philosophy of language with propositions, properties, etc. In particular, they may not have very strong intuitions or arguments for such positions, and the debate on abstracta can guide them one way or another. Their new intuitions can then be used to guide them in other areas, much like a broad physical theory might bring new ways of answering old questions along with new questions that (possibly) can be tested experimentally.

  • Do you have an example of a practical, everyday situation where the distinction makes a difference? Such as deciding between two jobs, or how far to inconvenience myself to try to recycle more? (I have no simple way to recycle aluminum beverage cans, the most vital thing to recycle. Other people near me have curbside recycling collection - effortless to them.)
    – Scott Rowe
    Sep 5, 2022 at 14:01
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    Thanks much and I mostly agree with you. I do want to say that having a more complete theory of physics CAN have practical uses, even if we don't see those uses before having the theory. It wasn't clear to people how the theory of relativity could be useful as it is well approximated by Newtonian theory in most scenarios, but later people launched satellites where Einsteinian physics actually mattered. I suspect the same could be true about a unifying theory of physics. In contrast, I don't see how ontological debates can (under any circumstances) have plausible practical implications.
    – J Li
    Sep 5, 2022 at 15:15
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    @ScottRowe theologians (some) have thought that the abstracta debate settles whether or not God is omnipotent or not. If you are a believer, you might find that to be of some practical importance. Otherwise I can't think of anything else. @J Li mostly agreed, the physics analogy was just that - an analogy.
    – emesupap
    Sep 5, 2022 at 16:20
  • @Papuseme Makes sense! Thanks much.
    – J Li
    Sep 6, 2022 at 1:40
  • @JLi ontological debates cannot have plausible practical implications Consider this account of what follows: youtube.com/watch?v=Zh3Yz3PiXZw. More staidly and bluntly if there's no platonism there's no such thing as truth. Just convention. Or what the teacher said. Or the answer at the back of the book etc. There's no authority beyond
    – Rushi
    Sep 22, 2022 at 13:20

There is an important and very practical difference when it comes to ethics (as in "how to live your life properly") and the consequences of either way of thinking when used as axioms.

Platonism holds that ideas do exist by themselves and are the purest form of existence. Things and living beings are but mere approximations, imperfect realizations of those ideas. For exemple, the idea of a Person exists, and as the purest form of person there can be as all the virtues that we might expect of a person. We on the other hand are only imperfect embodiments of this idea, just like a square we draw on paper is an imperfect representation of the idea of Square. The sides are not exactly straight or equal, the angles never perfectly 90 degrees, in the same way that we will never be as honest, as courageous or as wise as the perfect idea of a Person.

As a result, under a Platonist view, we humans are always lacking, always imperfect. All our self improvement can bring us closer to the idea of a person, but we will never reach it. Now add to this that the ideas of gendered Man, Woman, Citizen, Soldier, Worker etc do also exist and you can see in how many many dimensions we are lacking, never good enough (it can seem terribly self centered to demand that people conform to OUR idea. But keep in mind that a perfect idea under idealism is not a mere opinion, but universal truth that was reached by the careful application of reasoning).

On the other hand nominalism posits that our idea of a person was constructed out of the many individuals we met that could be clustered into the category of "person". Individuals exist before the idea, they are what really is.

As a result, when an individual does not match our idea of a person, it is not the individual who is lacking, but our idea, our preconceived notion of person, that is inadequate. As this idea exists only in our thoughts, individuals that don't match with it can't be held responsible for this discrepancy. Obviously, it is our idea that has to be changed in a way to match new data.

(About the concept of inadequate ideas, see Spinoza's Ethics. An inadequate idea is roughly speaking an idea that does not match reality.)

So why care? We can see that, depending on our ontology, our expectations toward others and ourselves change dramatically. Let's say you promised yourself to stop smoking but can't help having a cigarette from time to time. Are you an imperfect embodiment of the ideal Person, lacking in willpower and wisdom, and should you kick yourself mentally until you reach this standard of perfection? Or is it just a fact of life, that you overestimated your commitment and should reconsider if you really want to stop smoking, or change your strategy by avoiding temptation in the vicinity of tobacco or smokers?

Idealism can be motivational by setting for ourselves high goals, but also a lot of stress as we constantly fail to match expectations. It also shapes our view of others, setting high standards for the people around us but also leading to a very demanding attitude, as we expect others to comply to our vision of what they should be. Roughly speaking, it accords itself better with deontology or virtue ethics: since there is but one true idea of what a proper person is, it's only logical that everybody should strive toward fully realizing this idea. We and other people are responsible for not conforming to the pure, existing idea of what we should be.

Nominalism on the other hand leads to an approach of ethics much less demanding but also more free. It can lead to whataboutism and a slacking attitude, after all we are what we are, why try and improve toward a goal that has no real existence? But also it leaves us free to fix our own goal, our own vision of what we ought to be (See Sartres' existentialism. Nietzsche also comes to mind). It also leaves each of us responsible for revising our standards in accordance to reality: if people don't act as we expect them to, it's not them that are imperfect but our expectations that need revising. A nominalist ethic would probably tend towards consequentialism, as it is more difficult to argue for the existence of a universal idea of duty if ideas dont exist by themselves.

For a real life, current example of why it matters we can look at the public debate about the notion of gender.

The idealist approach is to posit that there are the idea of Man and Woman, that those ideas are eternal and fixed and that people who do not conform to those standards are lacking in some way: delicate or passive men are imperfect, effeminate Men, butch or bossy women are imperfect, boyish women.

A nominalist approach posits that the ideas of man and woman are constructed and that people who do not conform to it are not at fault, that it is those standards that should be reconsidered or entirely abandoned. Some men just happen to be delicate and some women butch, and we should not expect them to be other than they are.

If you pay attention to the talking points on both side of the controversy, you will notice how each is heavily based on one of those opposed ontological axioms (even if they don't make it explicit or realise it by themselves) and would be put in extreme rhetorical difficulty if their own axiom was to be denied.

Another example is politics and the Law. Does the set of perfect laws for the city exist by itself somewhere, and then what we call politics is just a way to approximate this perfect legislation? Or are laws just a social construct and politics a way to reach a consensus toward a reasonably efficient set of rules? The former would tend to favor aristocracy (in its original, platonic, meaning of "rule by the best, the wisest"), while the latter would tend to favor democracy, as the more citizens participate in lawmaking the more it is possible to reach a consensual result.

And that is why we should care about the nominalism VS idealism debate.

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    Please do not use the comment section to rant or blow steam about the gender controversy. This is just an example, not the subject.
    – armand
    Sep 5, 2022 at 4:51
  • The partisan, straw-man politics does a disservice to this answer, and serves as more than an example as it misrepresents the thinking underlying the positions relevant to the subject. Sep 5, 2022 at 6:17
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    @JustSomeOldMan A specific description of what is wrong according to you would have made your comment noteworthy. To the contrary, I have made a voluntary effort toward neutrality. But I guess to the militant mind neutrality is already too much to tolerate.
    – armand
    Sep 5, 2022 at 7:00
  • It depends on where you put zero on your value scale. If you put it at the top, it is the Idealist or religious scale: no one ever achieves the ideal. If at the bottom, no one should be judged harshly, but instead helped to improve. If in the middle, there are good and bad people, or actions or motives, etc. If you erase the scale, you have relativism, yes?
    – Scott Rowe
    Sep 5, 2022 at 13:58
  • Thank you for the answer. I find it very helpful. In some sense, you are adding one more dimension to Platonism that I didn't think about: if we think of the abstract ideas as something to strive for in a moral sense, then yes, that clearly has practical implications. As such, may I ask if this is a common attitude of modern-day philosophers who embrace Platonism? Are there references I can look into? (I apologize for my lack of knowledge on this topic; the answer may be very obvious)
    – J Li
    Sep 5, 2022 at 15:21

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