In a very flat manner, my question would be: what is realism in philosophy, which movements and authors belong to realism, and what does it oppose to?

But here are the precise issues that pop up each time I encounter "realism":

It seems realism is opposed to idealism, in the sense that realism, in opposition to idealism, recognizes the existence of a reality independent from the subject.

But it seems idealists often reject the view that they do not recognize reality, responding that this view is a falseful cliché, a caricature, when it fact idealism is just that truth can only be obtained through reason and ideas (Thomas-Fogiel, 2017), while not necessarily rejecting the existence of an independent reality.

On the other hand, we can see expressions such as "empiricist realism", as if empiricism were realist, and idealism weren't.

All and all, I feel that realism is not a real current of thoughts, but a term used to discredit the intellectual adversary. Is this intuition correct?


Thomas-Fogiel, I. (2017). L’opposition entre réalisme et idéalisme? Genèse et structure d’un contresens. Revue de métaphysique et de morale, (3), 393-426.

  • See Realism. Commented Feb 7, 2023 at 15:03
  • 5
    Realism is opposed to anti-realism, not to idealism. Many idealist philosophies are realist, from Plato's and Leibniz's to Hegel's and Whitehead's. The opposite of (realist) idealism is materialism, but they disagree on the nature of reality, not on its independent existence.
    – Conifold
    Commented Feb 7, 2023 at 15:37
  • 1
    What do you mean with "Is realism real?" If realism means a philosophical idea/school, then YES. Commented Feb 8, 2023 at 6:39
  • @MauroALLEGRANZA “If realism means a philosophical idea/school” this is what I meant. Thank you
    – Starckman
    Commented Feb 8, 2023 at 7:31
  • I'm wondering about anti-idealism.
    – Scott Rowe
    Commented Feb 8, 2023 at 17:30

3 Answers 3


Realism is opposed to anti-realism. (SEP) Since there are many forms of realism, one will talk about scientific realism as opposed to direct realism or skeptical realism since modern scientific methods have attained a favored status as epistemological methods. From the article:

Debates about scientific realism concern the extent to which we are entitled to hope or believe that science will tell us what the world is really like. Realists tend to be optimistic; antirealists do not. To a first approximation, scientific realism is the view that well-confirmed scientific theories are approximately true; the entities they postulate do exist; and we have good reason to believe their main tenets. Realists often add that, given the spectacular predictive, engineering, and theoretical successes of our best scientific theories, it would be miraculous were they not to be approximately correct. This natural line of thought has an honorable pedigree yet has been subject to philosophical dispute since modern science began.

Idealism (SEP) which was very fashionable in the 19th century is generally opposed to materialism, which pits mind against body in the question of how to handle mind-body dualism (IEP). In the extreme, Berkeley proposed what is now called subject idealism, that the mind is the center of all things (with a little help from God, the chief Mind) and which is often claimed to oppose in the extreme eliminative materialism, which claims the mind is an illusion. There are positions between. But idealism has a number of phases, such as German, British, and American idealism and is a broad swath of doctrines. From the SEP article above:

It is also remarkable that the term “idealism”, at least within philosophy, is often used in such a way that it gets its meaning through what is taken to be its opposite: as the meaningful use of the term “outside” depends on a contrast with something considered to be inside, so the meaning of the term “idealism” is often fixed by what is taken to be its opposite. Thus, an idealist is someone who is not a realist, not a materialist, not a dogmatist, not an empiricist, and so on. Given the fact that many also want to distinguish between realism, materialism, dogmatism, and empiricism, it is obvious that thinking of the meaning of “idealism” as determined by what it is meant to be opposed to leads to further complexity and gives rise to the impression that underlying such characterizations lies some polemical intent.

  • "Debates about scientific realism concern the extent to which we are entitled to hope or believe that science will tell us what the world is really like. Realists tend to be optimistic; antirealists do not." So logical positivists are realists!
    – Starckman
    Commented Feb 8, 2023 at 8:48
  • "Idealism (SEP) which was very fashionable in the 19th century is generally opposed to materialism" I wanted to ask in my post the relation between realism and materialism. Why did you mention "materialism" here?
    – Starckman
    Commented Feb 8, 2023 at 8:50
  • "Thus, an idealist is someone who is not a realist" but then why it can be said "Many idealist philosophies are realist, from Plato's and Leibniz's to Hegel's and Whitehead's." (see the comment of Conifold under my post. I am not able to poke Conifold, I don't know why)
    – Starckman
    Commented Feb 8, 2023 at 8:55

Realism is a generic position that philosophers often apply to certain thing but not others. That is, most philosophers are realists with respect to some things but anti-realists with respect to other things. For example, one can believe that physical objects are real but abstract objects are not, or one can believe that distributed wholes are real but sets are not.

In general to say that a class of objects is real is to say that objects of that class exist on their own and are not to be explained by or reduced to other objects. A realist is one who claims, with respect to some class, that objects of that class are real. An anti-realist claims the opposite.

The difference between a realism debate and an existence debate is that in a realism debate, both sides agree that the class of objects under discussion exists in some sense or at least that most common propositions about the objects are true, but they differ on how to account for the objects. That is, they are not arguing over the truth of statements about the objects, but about what underlies those statements. For example, someone who is not a realist with respect to mathematical objects could still claim that mathematics is true, but someone who denies the existence of God would not generally say that common statements about God are true. Thus, there are mathematical realists but not God realists. The debate about God is an existence debate, not a realism debate.

The most general contrast is not between realist and idealist but between realist and reductionist. A reductionist is someone who claims, for some general class of objects, that objects of that class are really something else. For example, some philosophers have claimed that the objects of mathematics are really just marks on paper, that mathematics is just a game played with symbols (this position is sometimes called nominalism, but should more properly be called formalism).

In some of the most important debates, the reductionists are idealists; that is, they try to reduce the objects under consideration to ideas, mental events. There is an idealist account of mathematical objects in which mathematical objects are viewed as ideas in the head rather than abstract objects.

The most well-known realist/idealist debate is that with respect to the physical world. A realist with respect to the physical world is someone who claims that at least some physical objects (or at least physical fields or events) are real and are not to be explained in terms of anything non-physical. An idealist is one who reduces all physical objects and events to the subjective impressions or sensations that we receive from them.

In the debate over the physical world there isn't any commonly held third opinion, so in this debate, realism and idealism are often treated as the only two possibilities.

  • "are real and are not to be explained in terms of anything non-physical. An idealist is one who reduces all physical objects and events to sense impressions." To me, "Sense impressions" are physical, and idealism is about ideas, representations, rather than senses.
    – Starckman
    Commented Feb 9, 2023 at 6:37
  • @Starckman, if you say sense impressions are physical, then you aren't talking about what philosophers are talking about. Sense impressions are specifically subjective and mental. Commented Feb 9, 2023 at 7:12
  • But when empiricists say knowledge must be acquired through the sensible experience, they are not talking about "impressions" right? But about "sensations", "senses", etc.
    – Starckman
    Commented Feb 9, 2023 at 7:16
  • "impression" to me is really echoing Plato's allegory of the cave
    – Starckman
    Commented Feb 9, 2023 at 7:18
  • 1
    @Starckman, on the one hand, I'm sure "sense impression" is used to refer to the subjective and mental, but on the other hand you are right that it does arguably imply the existence of physical senses. I'm 95% sure my original statement is correct, but due to that 5% chance I'm misremembering, I'll change the wording to avoid it. Commented Feb 9, 2023 at 7:57

Physics has had to define "realism" explicitly in testing QM vs relativity theories. This was driven by Einstein's admirable work to actually test between different "interpretations" of QM -- showing those "interpretations" can and do have real world and testable differences. IE they are actually different theories, not different interpretations of the same theory.

The tests that I am particularly interested in are based on something called Bell's Inequality. Bell came up with a way to test whether a quantum event would demonstrate "local realism" or not. Where "local" means that interactions are limited by the constraints of light speed, and "realism" is taken as the idea that there is an observer independent feature to our universe (observer is not needed to be included in the description to describe the event/universe). Here is a good blog discussion of Bell's Inequality: https://www.nist.gov/blogs/taking-measure/local-realism-bells-inequality-and-t-shirts-entangled-tale Note I disagree with the blogger who claims that all QM interpretations are merely interpretations. This view is refuted by our having been able to falsify and reject multiple "interpretations" proposed by Einstein, in his efforts to come up with a deterministic "interpretation" of QM.

What this physics application shows, is that NO -- "realism" is not just rhetoric. It is a definable criteria, and can be tested for in our universe.

Now, lots of people in philosophy or rhetoric CAN misuse such a term, and misuse it for namecalling/polemical purposes. And "realism" seems like it is ripe for just that sort of misuse, given how difficult it is to define and use properly. So -- it is very plausible that your intuitions that most of the use of "realism" in philosophy is just rhetoric/polemics could be true as well. And I suspect it is.

  • Maybe meta-physics can test idealism against quantum humanics.
    – Scott Rowe
    Commented Feb 8, 2023 at 17:35

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