In metaphysics, nominalism is a philosophical view which denies the existence of universals and abstract objects, but affirms the existence of general or abstract terms and predicates.[1] There are at least two main versions of nominalism. One version denies the existence of universals – things that can be instantiated or exemplified by many particular things (e.g., strength, humanity). The other version specifically denies the existence of abstract objects – objects that do not exist in space and time.[2]

Most nominalists have held that only physical particulars in space and time are real, and that universals exist only post res, that is, subsequent to particular things.[3] However, some versions of nominalism hold that some particulars are abstract entities (e.g., numbers), while others are concrete entities – entities that do exist in space and time (e.g., pillars, snakes, bananas).

Nominalism is primarily a position on the problem of universals, which dates back at least to Plato, and is opposed to realist philosophies, such as Platonic realism, which assert that universals do exist over and above particulars. However, the name "nominalism" emerged from debates in medieval philosophy with Roscellinus.

The term 'nominalism' stems from the Latin nomen, "name". John Stuart Mill summarised nominalism in the apothegm "there is nothing general except names".[4]

In philosophy of law, nominalism finds its application in what is called constitutional nominalism.[5]


Ancient Greek philosophy

Plato was perhaps the first[6] writer in Western philosophy to clearly state a non-nominalist position:

...We customarily hypothesize a single form in connection with each of the many things to which we apply the same name. ... For example, there are many beds and tables. ... But there are only two forms of such furniture, one of the bed and one of the table. (Republic 596a-b, trans. Grube)

What about someone who believes in beautiful things, but doesn't believe in the beautiful itself…? Don't you think he is living in a dream rather than a wakened state? (Republic 476c)

The Platonic universals corresponding to the names "bed" and "beautiful" were the Form of the Bed and the Form of the Beautiful, or the Bed Itself and the Beautiful Itself. Platonic Forms were the first universals posited as such in philosophy.[6]

Our term "universal" is due to the English translation of Aristotle's technical term katholou which he coined specially for the purpose of discussing the problem of universals.[7] Katholou is a contraction of the phrase kata holou, meaning "on the whole".[8]

Aristotle famously rejected certain aspects of Plato's Theory of Forms, but he clearly rejected nominalism as well:

...'Man', and indeed every general predicate, signifies not an individual, but some quality, or quantity or relation, or something of that sort. (Sophistical Refutations xxii, 178b37, trans. Pickard-Cambridge)

The first philosophers to explicitly describe nominalist arguments were the Stoics, especially Chrysippus.[9][10]

Medieval philosophy

In medieval philosophy, the French philosopher and theologian Roscellinus (c. 1050 – c. 1125) was an early, prominent proponent of nominalism. Nominalist ideas can be found in the work of Peter Abelard and reached their flowering in William of Ockham, who was the most influential and thorough nominalist. Abelard's and Ockham's version of nominalism is sometimes called conceptualism, which presents itself as a middle way between nominalism and realism, asserting that there is something in common among like individuals, but that it is a concept in the mind, rather than a real entity existing independently of the mind. Ockham argued that only individuals existed and that universals were only mental ways of referring to sets of individuals. "I maintain", he wrote, "that a universal is not something real that exists in a subject... but that it has a being only as a thought-object in the mind [objectivum in anima]". As a general rule, Ockham argued against assuming any entities that were not necessary for explanations. Accordingly, he wrote, there is no reason to believe that there is an entity called "humanity" that resides inside, say, Socrates, and nothing further is explained by making this claim. This is in accord with the analytical method that has since come to be called Ockham's razor, the principle that the explanation of any phenomenon should make as few assumptions as possible. Critics argue that conceptualist approaches only answer the psychological question of universals. If the same concept is correctly and non-arbitrarily applied to two individuals, there must be some resemblance or shared property between the two individuals that justifies their falling under the same concept and that is just the metaphysical problem that universals were brought in to address, the starting-point of the whole problem (MacLeod & Rubenstein, 2006, §3d). If resemblances between individuals are asserted, conceptualism becomes moderate realism; if they are denied, it collapses into nominalism.[11]

Modern and contemporary philosophy

In modern philosophy, nominalism was revived by Thomas Hobbes[12] and Pierre Gassendi.[13]

In contemporary analytic philosophy, it has been defended by Rudolf Carnap,[14] Nelson Goodman,[15] H. H. Price,[14] and D. C. Williams.[16]

Indian philosophy

The debate between realism and nominalism also took place in Indian philosophy. Certain orthodox Hindu schools (eg., Purva Mimamsa, Nyaya and Vaisheshika) defended the realist position, saying that the referent of the word is both the individual thing perceived by the subject of knowledge and the class to which the thing belongs. According to Indian realism, both the individual and the class have objective existence, with the second underlying the former.

The Buddhists, especially those of the Yogacara school, took the nominalist position; they were of the opinion that words have as referent, not true objects, but only concepts produced in the intellect. These concepts are not real since they do not have efficient existence, that is, causal powers. Words, as linguistic conventions, are useful to thought and discourse, but even so, it should not be accepted that words apprehend reality as it is.

Dignaga, a Yogacara philosopher, formulated a nominalist theory of meaning called apoha, or theory of exclusions. The theory seeks to explain how it is possible for words to refer to classes of objects even if no such class has an objective existence. Dignaga's thesis is that classes do not refer to positive qualities that their members share in common. On the contrary, classes are exclusions (apoha). As such, the "cow" class, for example, is composed of all exclusions common to individual cows: they are all non-horse, non-elephant, etc.

Among Hindu realists, this thesis was criticized for being negative.

The problem of universals

Nominalism arose in reaction to the problem of universals, specifically accounting for the fact that some things are of the same type. For example, Fluffy and Kitzler are both cats, or, the fact that certain properties are repeatable, such as: the grass, the shirt, and Kermit the Frog are green. One wants to know by virtue of what are Fluffy and Kitzler both cats, and what makes the grass, the shirt, and Kermit green.

The Platonist answer is that all the green things are green in virtue of the existence of a universal: a single abstract thing that, in this case, is a part of all the green things. With respect to the color of the grass, the shirt and Kermit, one of their parts is identical. In this respect, the three parts are literally one. Greenness is repeatable because there is one thing that manifests itself wherever there are green things.

Nominalism denies the existence of universals. The motivation for this flows from several concerns, the first one being where they might exist. Plato famously held, on one interpretation, that there is a realm of abstract forms or universals apart from the physical world (see theory of the forms). Particular physical objects merely exemplify or instantiate the universal. But this raises the question: Where is this universal realm? One possibility is that it is outside space and time. A view sympathetic with this possibility holds that, precisely because some form is immanent in several physical objects, it must also transcend each of those physical objects; in this way, the forms are "transcendent" only insofar as they are "immanent" in many physical objects. In other words, immanence implies transcendence; they are not opposed to one another. (Nor, in this view, would there be a separate "world" or "realm" of forms that is distinct from the physical world, thus shirking much of the worry about where to locate a "universal realm".) However, naturalists assert that nothing is outside of space and time. Some Neoplatonists, such as the pagan philosopher Plotinus and the Christian philosopher Augustine, imply (anticipating conceptualism) that universals are contained within the mind of God. To complicate things, what is the nature of the instantiation or exemplification relation?

Conceptualists hold a position intermediate between nominalism and realism, saying that universals exist only within the mind and have no external or substantial reality.

Moderate realists hold that there is no realm in which universals exist, but rather universals are located in space and time wherever they are manifest. Now, recall that a universal, like greenness, is supposed to be a single thing. Nominalists consider it unusual that there could be a single thing that exists in multiple places simultaneously. The realist maintains that all the instances of greenness are held together by the exemplification relation, but this relation cannot be explained.

Finally, many philosophers prefer simpler ontologies populated with only the bare minimum of types of entities, or as W. V. O. Quine said "They have a taste for 'desert landscapes.'" They try to express everything that they want to explain without using universals such as "catness" or "greenness."


There are various forms of nominalism ranging from extreme to almost-realist. One extreme is predicate nominalism, which states that Fluffy and Kitzler, for example, are both cats simply because the predicate 'is a cat' applies to both of them. And this is the case for all similarity of attribute among objects. The main criticism of this view is that it does not provide a sufficient solution to the problem of universals. It fails to provide an account of what makes it the case that a group of things warrant having the same predicate applied to them.[17]

Proponents of resemblance nominalism believe that 'cat' applies to both cats because Fluffy and Kitzler resemble an exemplar cat closely enough to be classed together with it as members of its kind, or that they differ from each other (and other cats) quite less than they differ from other things, and this warrants classing them together.[18] Some resemblance nominalists will concede that the resemblance relation is itself a universal, but is the only universal necessary. Others argue that each resemblance relation is a particular, and is a resemblance relation simply in virtue of its resemblance to other resemblance relations. This generates an infinite regress, but many argue that it is not vicious.[19]

Class nominalism argues that class membership forms the metaphysical backing for property relationships: two particular red balls share a property in that they are both members of classes corresponding to their properties—that of being red and being balls. A version of class nominalism that sees some classes as "natural classes" is held by Anthony Quinton.[20]

Conceptualism is a philosophical theory that explains universality of particulars as conceptualized frameworks situated within the thinking mind.[21] The conceptualist view approaches the metaphysical concept of universals from a perspective that denies their presence in particulars outside of the mind's perception of them.[22]

Another form of nominalism is trope nominalism. A trope is a particular instance of a property, like the specific greenness of a shirt. One might argue that there is a primitive, objective resemblance relation that holds among like tropes. Another route is to argue that all apparent tropes are constructed out of more primitive tropes and that the most primitive tropes are the entities of complete physics. Primitive trope resemblance may thus be accounted for in terms of causal indiscernibility. Two tropes are exactly resembling if substituting one for the other would make no difference to the events in which they are taking part. Varying degrees of resemblance at the macro level can be explained by varying degrees of resemblance at the micro level, and micro-level resemblance is explained in terms of something no less robustly physical than causal power. David Armstrong, perhaps the most prominent contemporary realist, argues that such a trope-based variant of nominalism has promise, but holds that it is unable to account for the laws of nature in the way his theory of universals can.

Ian Hacking has also argued that much of what is called social constructionism of science in contemporary times is actually motivated by an unstated nominalist metaphysical view. For this reason, he claims, scientists and constructionists tend to "shout past each other".[23]

Analytic philosophy and mathematics

A notion that philosophy, especially ontology and the philosophy of mathematics should abstain from set theory owes much to the writings of Nelson Goodman (see especially Goodman 1940 and 1977), who argued that concrete and abstract entities having no parts, called individuals exist. Collections of individuals likewise exist, but two collections having the same individuals are the same collection. Goodman was himself drawing heavily on the work of Stanisław Leśniewski, especially his mereology, which was itself a reaction to the paradoxes associated with Cantorian set theory. Leśniewski denied the existence of the empty set and held that any singleton was identical to the individual inside it. Classes corresponding to what are held to be species or genera are concrete sums of their concrete constituting individuals. For example, the class of philosophers is nothing but the sum of all concrete, individual philosophers.

The principle of extensionality in set theory assures us that any matching pair of curly braces enclosing one or more instances of the same individuals denote the same set. Hence {a, b}, {b, a}, {a, b, a, b} are all the same set. For Goodman and other nominalists, {a, b} is also identical to {a, {b} }, {b, {a, b} }, and any combination of matching curly braces and one or more instances of a and b, as long as a and b are names of individuals and not of collections of individuals. Goodman, Richard Milton Martin, and Willard Quine all advocated reasoning about collectivities by means of a theory of virtual sets (see especially Quine 1969), one making possible all elementary operations on sets except that the universe of a quantified variable cannot contain any virtual sets.

In the foundation of mathematics, nominalism has come to mean doing mathematics without assuming that sets in the mathematical sense exist. In practice, this means that quantified variables may range over universes of numbers, points, primitive ordered pairs, and other abstract ontological primitives, but not over sets whose members are such individuals. To date, only a small fraction of the corpus of modern mathematics can be rederived in a nominalistic fashion.


Critique of the historical origins of the term

As a category of late medieval thought, the concept of 'nominalism' has been increasingly queried. Traditionally, the fourteenth century has been regarded as the heyday of nominalism, with figures such as John Buridan and William of Ockham viewed as founding figures. However, the concept of 'nominalism' as a movement (generally contrasted with 'realism'), first emerged only in the late fourteenth century,[24] and only gradually became widespread during the fifteenth century.[25] The notion of two distinct ways, a via antiqua, associated with realism, and a via moderna, associated with nominalism, became widespread only in the later fifteenth century – a dispute which eventually dried up in the sixteenth century.[26]

Aware that explicit thinking in terms of a divide between 'nominalism' and 'realism' only emerged in the fifteenth century, scholars have increasingly questioned whether a fourteenth-century school of nominalism can really be said to have existed. While one might speak of family resemblances between Ockham, Buridan, Marsilius and others, there are also striking differences. More fundamentally, Robert Pasnau has questioned whether any kind of coherent body of thought that could be called 'nominalism' can be discerned in fourteenth century writing.[27] This makes it difficult, it has been argued, to follow the twentieth century narrative which portrayed late scholastic philosophy as a dispute which emerged in the fourteenth century between the via moderna, nominalism, and the via antiqua, realism, with the nominalist ideas of William of Ockham foreshadowing the eventual rejection of scholasticism in the seventeenth century.[26]

Critique of nominalist reconstructions in mathematics

A critique of nominalist reconstructions in mathematics was undertaken by Burgess (1983) and Burgess and Rosen (1997). Burgess distinguished two types of nominalist reconstructions. Thus, hermeneutic nominalism is the hypothesis that science, properly interpreted, already dispenses with mathematical objects (entities) such as numbers and sets. Meanwhile, revolutionary nominalism is the project of replacing current scientific theories by alternatives dispensing with mathematical objects (see Burgess, 1983, p. 96). A recent study extends the Burgessian critique to three nominalistic reconstructions: the reconstruction of analysis by Georg Cantor, Richard Dedekind, and Karl Weierstrass that dispensed with infinitesimals; the constructivist re-reconstruction of Weierstrassian analysis by Errett Bishop that dispensed with the law of excluded middle; and the hermeneutic reconstruction, by Carl Boyer, Judith Grabiner, and others, of Cauchy's foundational contribution to analysis that dispensed with Cauchy's infinitesimals.[28]

See also


  1. ^ Mill (1872); Bigelow (1998).
  2. ^ Rodriguez-Pereyra (2008) writes: "The word 'Nominalism', as used by contemporary philosophers in the Anglo-American tradition, is ambiguous. In one sense, its most traditional sense deriving from the Middle Ages, it implies the rejection of universals. In another, more modern but equally entrenched sense, it implies the rejection of abstract objects" (§1).
  3. ^ Feibleman (1962), p. 211.
  4. ^ Mill, J.S. (1865/1877). An Examination of Sir William Hamilton's Philosophy, volume II, Chapter XVII, page 50.
  5. ^ An overview of the philosophical problems and an application of the concept to a case of the Supreme Court of the State of California, gives Thomas Kupka, 'Verfassungsnominalismus', in: Archives for Philosophy of Law and Social Philosophy 97 (2011), 44–77, PDF.
  6. ^ a b Penner (1987), p. 24.
  7. ^ Peters (1967), p. 100.
  8. ^ "katholou" in Harvard's Archimedes Project online version of Liddell & Scott's A Greek-English Lexicon.
  9. ^ 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.".
  10. ^ Chrysippus (Internet Encyclopedia of Philosophy)
  11. ^ "Meaning and the Problem of Universals".
  12. ^ Thomas Hobbes (Stanford Encyclopedia of Philosophy)
  13. ^ Pierre Gassendi (Stanford Encyclopedia of Philosophy)
  14. ^ a b "Review of Gonzalo Rodriguez-Pereyra, Resemblance Nominalism: A Solution to the Problem of Universals" –
  15. ^ "Nelson Goodman: The Calculus of Individuals in its different versions", Stanford Encyclopedia of Philosophy
  16. ^ Donald Cary Williams, Stanford Encyclopedia of Philosophy.
  17. ^ MacLeod & Rubenstein (2006), §3a.
  18. ^ MacLeod & Rubenstein (2006), §3b.
  19. ^ See, for example, H. H. Price (1953).
  20. ^ Quinton, Anthony (1957). "Properties and Classes". Proceedings of the Aristotelian Society. 58: 33–58. JSTOR 4544588.
  21. ^ Strawson, P. F. "Conceptualism." Universals, concepts and qualities: new essays on the meaning of predicates. Ashgate Publishing, 2006.
  22. ^ "Conceptualism." The Oxford Dictionary of Philosophy. Simon Blackburn. Oxford University Press, 1996. Oxford Reference Online. Oxford University Press. 8 April 2008.
  23. ^ Hacking (1999), pp. 80-84.
  24. ^ The classic starting point of nominalism has been the edict issued by Louis XI in 1474 commanding that realism alone (as contained in scholars such as Averroes, Albert the Great, Aquinas, Duns Scotus and Bonaventure) be taught at the University of Paris, and ordering that the books of various 'renovating scholars', including Ockham, Gregory of Rimini, Buridan and Peter of Ailly be removed. The edict used the word 'nominalist' to describe those students at Paris who 'are not afraid to imitate' the renovators. These students then made a reply to Louis XI, defending nominalism as a movement going back to Ockham, which had been persecuted repeatedly, but which in fact represents the truer philosophy. See Robert Pasnau, Metaphysical Themes, 1274-1671, (New York: OUP, 2011), p. 85.
  25. ^ For example, when Jerome of Prague visited the University of Heidelberg in 1406, he described the nominalists as those who deny the reality of universals outside the human mind, and realists as those who affirm that reality. Also, for instance, in a 1425 document from the University of Cologne which draws a distinction between the via of Thomas Aquinas, Albert the Great, and the via of the 'modern masters' John Buridan and Marsilius of Inghen. See Robert Pasnau, Metaphysical Themes, 1274-1671, (New York: OUP, 2011), p84.
  26. ^ a b See Robert Pasnau, Metaphysical Themes, 1274-1671, (New York: OUP, 2011), p84.
  27. ^ See Robert Pasnau, Metaphysical Themes, 1274-1671, (New York: OUP, 2011), p86.
  28. ^ Usadi Katz, Karin; Katz, Mikhail G. (2011). "A Burgessian Critique of Nominalistic Tendencies in Contemporary Mathematics and its Historiography". Foundations of Science. arXiv:1104.0375. doi:10.1007/s10699-011-9223-1.

References and further reading

  • Adams, Marilyn McCord. William of Ockham (2 volumes) Notre Dame, IN: Notre Dame University Press, 1987.
  • American Heritage Dictionary of the English Language, Fourth Edition, 2000.
  • Borges, Jorge Luis (1960). "De las alegorías a las novelas" in Otras inquisiciones (pg 153-56).
  • Burgess, John (1983). Why I am not a nominalist. Notre Dame J. Formal Logic 24, no. 1, 93–105.
  • Burgess, John & Rosen, Gideon. (1997). A Subject with no Object. Princeton University Press.
  • Courtenay, William J. Adam Wodeham: An Introduction to His Life and Writings, Leiden: E. J. Brill, 1978.
  • Feibleman, James K. (1962). "Nominalism" in Dictionary of Philosophy, Dagobert D. Runes (ed.). Totowa, NJ: Littlefield, Adams, & Co. (link)
  • Goodman, Nelson (1977) The Structure of Appearance, 3rd ed. Kluwer.
  • Hacking, Ian (1999). The Social Construction of What?, Harvard University Press.
  • Karin Usadi Katz and Mikhail G. Katz (2011) A Burgessian Critique of Nominalistic Tendencies in Contemporary Mathematics and its Historiography. Foundations of Science. doi:10.1007/s10699-011-9223-1 See link
  • Mill, J. S., (1872). An Examination of William Hamilton's Philosophy, 4th ed., Chapter XVII.
  • Oberman, Heiko. The Harvest of Medieval Theology: Gabriel Biel and Late Medieval Nominalism, Grand Rapids, MI: Baker Academic, 2001.
  • Penner, T. (1987). The Ascent from Nominalism, D. Reidel Publishing.
  • Peters, F. (1967). Greek Philosophical Terms, New York University Press.
  • Price, H. H. (1953). "Universals and Resemblance", Ch. 1 of Thinking and Experience, Hutchinson's University Library.
  • Quine, W. V. O. (1961). "On What There is," in From a Logical Point of View, 2nd/ed. N.Y: Harper and Row.
  • Quine, W. V. O. (1969). Set Theory and Its Logic, 2nd ed. Harvard University Press. (Ch. 1 includes the classic treatment of virtual sets and relations, a nominalist alternative to set theory.)
  • Robson, John Adam, Wyclif and the Oxford Schools: The Relation of the "Summa de Ente" to Scholastic Debates at Oxford in the Late Fourteenth Century, Cambridge, England: Cambridge University Press, 1961.
  • Utz, Richard, "Literary Nominalism." Oxford Dictionary of the Middle Ages. Ed. Robert E. Bjork. Oxford: Oxford University Press, 2010. Vol. III, p. 1000.
  • Russell, Bertrand (1912). "The World of Universals," in The Problems of Philosophy, Oxford University Press.
  • Williams, D. C. (1953). "On the Elements of Being: I", Review of Metaphysics, vol. 17, pp. 3–18.

External links

Anthony Quinton

Anthony Meredith Quinton, Baron Quinton, FBA (25 March 1925 – 19 June 2010) was a British political and moral philosopher, metaphysician, and materialist philosopher of mind.


In metaphysics, conceptualism is a theory that explains universality of particulars as conceptualized frameworks situated within the thinking mind. Intermediate between nominalism and realism, the conceptualist view approaches the metaphysical concept of universals from a perspective that denies their presence in particulars outside the mind's perception of them. Conceptualism is anti-realist about abstract objects, just like immanent realism is (their difference being that immanent realism accepts there are mind-indepedent facts about whether universals are instantiated).

Gregory of Rimini

Gregory of Rimini (c. 1300 – November 1358), also called Gregorius de Arimino or Ariminensis, was one of the great scholastic philosophers and theologians of the Middle Ages. He was the first scholastic writer to unite the Oxonian and Parisian traditions in 14th-century philosophy, and his work had a lasting influence in the Late Middle Ages and Reformation. His scholastic nicknames were Doctor acutus and Doctor authenticus.

Grzegorz of Stawiszyn

Grzegorz of Stawiszyn (Polish: Grzegorz ze Stawiszyna; 1481–1540), was a Polish philosopher and theologian of the mid 16th century, Rector of the University of Krakow in the years 1538-1540.Grzegorz was born in Stawiszyn in 1481. He was an adherent of Nominalism, a metaphysical view in philosophy, revived in western Europe at the turn of the sixteenth century thanks to French philosopher Jacques Lefèvre d'Étaples (Faber Stapulensis). Once Nominalism reappeared in Kraków and began taking precedence over Thomism and Scotism, Grzegorz of Stawiszyn, a Kraków professor, published Jacques d'Étaples works including his commentaries to works by Aristotle, beginning in 1510. As rector, Grzegorz introduced first reforms toward leaving the scholasticism of Peter of Spain at the University of Krakow beginning 1538, and replacing it with the Renaissance Aristotelianism, including classes in logic based on Dialectics of Jan Caesarius. He died in Krakow.

Ian Hacking

Ian MacDougall Hacking (born February 18, 1936) is a Canadian philosopher specializing in the philosophy of science. Throughout his career, he has won numerous awards, such as the Killam Prize for the Humanities and the Balzan Prize, and been a member of many prestigious groups, including the Order of Canada, the Royal Society of Canada and the British Academy.

Literary nominalism

Literary nominalism is a paradigm of thought that is interested in the interconnections between certain aspects of nominalist philosophy and theology and works of literature.

Moderate realism

Moderate realism (also called immanent realism) is a position in the debate on the metaphysics of universals which holds that there is no realm in which universals exist (in opposition to Platonic realism who asserts the existence of abstract objects), nor do they really exist within particulars as universals, but rather universals really exist within particulars as particularised, and multiplied.

Nelson Goodman

Henry Nelson Goodman (7 August 1906 – 25 November 1998) was an American philosopher, known for his work on counterfactuals, mereology, the problem of induction, irrealism, and aesthetics.

Notion (philosophy)

A notion in philosophy is a reflection in the mind of real objects and phenomena in their essential features and relations. Notions are usually described in terms of scope and content. This is because notions are often created in response to empirical observations (or experiments) of covarying trends among variables.

Notion is the common translation for Begriff as used by Hegel in his Science of Logic (1816).

Philosophical logic

Philosophical logic refers to those areas of philosophy in which recognized methods of logic have traditionally been used to solve or advance the discussion of philosophical problems. Among these, Sybil Wolfram highlights the study of argument, meaning, and truth, while Colin McGinn presents identity, existence, predication, necessity and truth as the main topics of his book on the subject.Philosophical logic also addresses extensions and alternatives to traditional, "classical" logic known as "non-classical" logics. These receive more attention in texts such as John P. Burgess's Philosophical Logic, the Blackwell Companion to Philosophical Logic, or the multi-volume Handbook of Philosophical Logic edited by Dov M. Gabbay and Franz Guenthner.

Philosophical realism

In metaphysics, realism about a given object is the view that this object exists in reality independently of our conceptual scheme. In philosophical terms, these objects are ontologically independent of someone's conceptual scheme, perceptions, linguistic practices, beliefs, etc.

Realism can be applied to many philosophically interesting objects and phenomena: other minds, the past or the future, universals, mathematical entities (such as natural numbers), moral categories, the physical world, and thought.

Realism can also be a view about the nature of reality in general, where it claims that the world exists independent of the mind, as opposed to non-realist views (like some forms of skepticism and solipsism, which question our ability to assert the world is independent of our mind). Philosophers who profess realism often claim that truth consists in a correspondence between cognitive representations and reality.Realists tend to believe that whatever we believe now is only an approximation of reality but that the accuracy and fullness of understanding can be improved. In some contexts, realism is contrasted with idealism. Today it is more usually contrasted with anti-realism, for example in the philosophy of science.

The oldest use of the term "realism" appears in medieval scholastic interpretations and adaptations of ancient Greek philosophy.

Problem of universals

In metaphysics, the problem of universals refers to the question of whether properties exist, and if so, what they are. Properties are qualities or relations that two or more entities have in common. The various kinds of properties, such as qualities and relations, are referred to as universals. For instance, one can imagine three cup holders on a table that have in common the quality of being circular or exemplifying circularity, or two daughters that have in common being the female offsprings of Frank. There are many such properties, such as being human, red, male or female, liquid, big or small, taller than, father of, etc. While philosophers agree that human beings talk and think about properties, they disagree on whether these universals exist in reality or merely in thought and speech.

The problem of universals relates to a number of questions in close relation to not only metaphysics but, to logic and epistemology, all in efforts to understand how the thought of universals has a connection to those of singular properties.

Psychological nominalism

Psychological nominalism is the view advanced in Wilfrid Sellars' paper "Empiricism and Philosophy of Mind" (EPM) that explains psychological concepts in terms of public language use. Sellars describes psychological nominalism as the view that “all awareness of sorts, resemblances, facts, etc., in short, all awareness…is a linguistic affair.”

Judging solely from the mention in EPM, psychological nominalism would seem to be a form of verbal behaviorism, which holds that ascriptions of psychological states are definitionally equivalent to predictions about behavior. For example, the verbal behaviorist holds that a statement like "John is scared of thunderstorms" is meaningful only insofar as it can be parsed into predictions concerning the sorts of things John is likely to say and/or do in the event of a thunderstom (i.e. "John will say, or have a propensity to say, "I am scared" when he hears thunder" or "John will hide, or have a propensity to hide, his face when he sees lightning").

Psychological nominalism extends the verbal behaviorist's explanation of psychological states (like fear, love, desire, thinking etc.) to cognitive states (being aware, knowing, etc.) while denying the premise that falsifiability criteria can give statements their meaning. The psychological nominalist concedes that survival of mental terminology in natural language can be explained in terms of the practical utility of mental-state ascriptions, but denies that this constitutes an analysis of the meaning of any particular mental-state ascription because the psychological nominalist contends that the meaning of any term, mental or otherwise, is irreducibly bound with its usage. Thus, the verbal behaviorist fails to give a completely philosophically satisfying account of psychological statements because he fails to recognize that the linguistic statements are themselves meaningful in light of the kinds of behavior associated with them.

Richard M. Weaver

Richard Malcolm Weaver, Jr (March 3, 1910 – April 1, 1963) was an American scholar who taught English at the University of Chicago. He is primarily known as an intellectual historian, political philosopher and a mid-20th century conservative and as an authority on modern rhetoric. Weaver was briefly a socialist during his youth, a lapsed leftist intellectual (conservative by the time he was in graduate school), a teacher of composition, a Platonist philosopher, cultural critic, and a theorist of human nature and society. Described by biographer Fred Young as a "radical and original thinker," Richard Weaver's books Ideas Have Consequences and The Ethics of Rhetoric remain influential among conservative theorists and scholars of the American South. Weaver was also associated with a group of scholars who in the 1940s and 1950s promoted traditionalist conservatism.


Roscelin of Compiègne (c. 1050 – c. 1125), better known by his Latinized name Roscellinus Compendiensis or Rucelinus, was a French philosopher and theologian, often regarded as the founder of nominalism.

Species concept

The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for sexually reproducing organisms such as birds is useless for species that reproduce asexually, such as bacteria. The scientific study of the species problem has been called microtaxonomy.One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from reproductive isolation with no interbreeding, to panmixis, unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others.

Many of the debates on species touch on philosophical issues, such as nominalism and realism, and on issues of language and cognition.

The current meaning of the phrase "species problem" is quite different from what Charles Darwin and others meant by it during the 19th and early 20th centuries. For Darwin, the species problem was the question of how new species arose. Darwin was however one of the first people to question how well-defined species are, given that they constantly change.

Trope (philosophy)

The term "trope" is both a term which denotes figurative and metaphorical language and one which has been used in various technical senses. The term trope derives from the Greek τρόπος (tropos), "a turn, a change", related to the root of the verb τρέπειν (trepein), "to turn, to direct, to alter, to change"; this means that the term is used metaphorically to denote, among other things, metaphorical language. Perhaps the term can be explained as meaning the same thing as a turn of phrase in its original sense.The term is also used in technical senses, which do not always correspond to its linguistic origin. Its meaning has to be judged from the context, some of which are given below.

Universal (metaphysics)

In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of which is green. These two chairs both share the quality of "chairness", as well as greenness or the quality of being green; in other words, they share a "universal". There are three major kinds of qualities or characteristics: types or kinds (e.g. mammal), properties (e.g. short, strong), and relations (e.g. father of, next to). These are all different types of universals.Paradigmatically, universals are abstract (e.g. humanity), whereas particulars are concrete (e.g. the personhood of Socrates). However, universals are not necessarily abstract and particulars are not necessarily concrete. For example, one might hold that numbers are particular yet abstract objects. Likewise, some philosophers, such as D. M. Armstrong, consider universals to be concrete.

Most do not consider classes to be universals, although some prominent philosophers do, such as John Bigelow.

William of Ockham

William of Ockham (; also Occam, from Latin: Gulielmus Occamus; c. 1287 – 1347) was an English Franciscan friar, scholastic philosopher, and theologian, who is believed to have been born in Ockham, a small village in Surrey. He is considered to be one of the major figures of medieval thought and was at the centre of the major intellectual and political controversies of the 14th century. He is commonly known for Occam's razor, the methodological principle that bears his name, and also produced significant works on logic, physics, and theology. In the Church of England, his day of commemoration is 10 April.

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