Editing Anti-realism (section)

=== Metaphysical anti-realism<!--'Metaphysical anti-realism' and 'Metaphysical antirealism' redirect here--> ===
{{also|Philosophical skepticism}}
One kind of '''metaphysical anti-realism'''<!--boldface per WP:R#PLA--> maintains a [[skepticism]] about the physical world, arguing either: 1) that nothing exists outside the mind, or 2) that we would have no access to a mind-independent reality, even if it exists.<ref>Karin Johannesson, ''[https://books.google.com/books?id=_ZPJb3iipY8C&q=%22anti-realism%22 God Pro Nobis: On Non-metaphysical Realism and the Philosophy of Religion]'', Peeters Publishers, 2007, p. 26.</ref> The latter case often takes the form of a denial of the idea that we can have 'unconceptualised' experiences (see [[Myth of the Given]]). Conversely, most realists (specifically, [[Indirect realism|indirect realists]]) hold that perceptions or [[sense data]] are caused by mind-independent objects. But this introduces the possibility of another kind of skepticism: since our understanding of [[causality]] is that the same effect can be produced by multiple causes, there is a [[Indeterminacy (philosophy)|lack of determinacy]] about what one is really perceiving, as in the [[brain in a vat]] scenario. The main alternative to this sort of metaphysical anti-realism is [[metaphysical realism]].

On a more abstract level, [[model theory|model-theoretic]] anti-realist arguments hold that a given set of [[symbol]]s in a [[theory]] can be mapped onto any number of sets of real-world objects&mdash;each set being a "model" of the theory—provided the relationship between the objects is the same (compare with [[symbol grounding]].)

In [[ancient Greek philosophy]], [[Problem of universals#Nominalism|nominalist (anti-realist) doctrines]] about [[universals (metaphysics)|universals]] were proposed by the [[Stoics]], especially [[Chrysippus]].<ref>John Sellars, ''Stoicism'', Routledge, 2014, pp. 84–85: "[Stoics] have often been presented as the first nominalists, rejecting the existence of universal concepts altogether. ... For Chrysippus there are no universal entities, whether they be conceived as substantial [[Platonic Forms]] or in some other manner."</ref><ref>{{cite web| url = https://www.iep.utm.edu/chrysipp/| title = Chrysippus – Internet Encyclopedia of Philosophy}}</ref> In [[early modern philosophy]], [[Conceptualism|conceptualist]] anti-realist doctrines about universals were proposed by thinkers like [[René Descartes]], [[John Locke]], [[Baruch Spinoza]], [[Gottfried Wilhelm Leibniz]], [[George Berkeley]], and [[David Hume]].<ref>[[David Bostock (philosopher)|David Bostock]], ''Philosophy of Mathematics: An Introduction'', Wiley-Blackwell, 2009, p. 43: "All of Descartes, Locke, Berkeley, and Hume supposed that mathematics is a theory of our ''ideas'', but none of them offered any argument for this conceptualist claim, and apparently took it to be uncontroversial."</ref><ref>Stefano Di Bella, Tad M. Schmaltz (eds.), ''The Problem of Universals in Early Modern Philosophy'', Oxford University Press, 2017, p. 64 "there is a strong case to be made that Spinoza was a ''conceptualist'' about universals" and p. 207 n. 25: "Leibniz's conceptualism [is related to] the Ockhamist tradition..."</ref> In [[late modern philosophy]], anti-realist doctrines about knowledge were proposed by the [[German idealist]] [[Georg Wilhelm Friedrich Hegel]]. Hegel was a proponent of what is now called [[Semantic inferentialism|inferentialism]]: he believed that the ground for the axioms and the foundation for the validity of the inferences are the right consequences and that the axioms do not explain the consequence.<ref>P. Stekeler-Weithofer (2016), [https://www.sozphil.uni-leipzig.de/cm/philosophie/files/2012/11/StekelerHegelsAnalyticPragmatism.pdf "Hegel's Analytic Pragmatism"] {{Webarchive|url=https://web.archive.org/web/20201103050351/https://www.sozphil.uni-leipzig.de/cm/philosophie/files/2012/11/StekelerHegelsAnalyticPragmatism.pdf |date=2020-11-03 }}, University of Leipzig, pp. 122–4.</ref> Kant and Hegel held conceptualist views about universals.<ref>Oberst, Michael. 2015. "Kant on Universals." ''History of Philosophy Quarterly'' '''32'''(4):335–352.</ref><ref>A. Sarlemijn, ''Hegel's Dialectic'', Springer, 1975, p. 21.</ref> In [[contemporary philosophy]], anti-realism was revived in the form of [[empirio-criticism]], [[logical positivism]], [[Semantic anti-realism (epistemology)|semantic anti-realism]] and scientific [[instrumentalism]] (see below).