Realism, Nominalism, Modality

There is an important intersection between the 14th century debate about realism and nominalism and contemporary questions about the status of modality in logic that ought to be of interest to non-specialists. Both of these topics probably sound obscure to most people. At sound-byte level, the first is about the status of universals, and modality is something we implicitly presuppose any time we try to reach for something “more” than allegedly pure phenomena or mere appearance.

Both sides of the medieval debate often wanted to enlist the support of Aristotle, who took a remarkably even-handed approach to these questions we have yet to clarify. The debate was often invested with a great moral significance, and provoked a number of intemperate claims. But at the same time, both sides were able to use the technical vocabulary of the theory of “supposition” — along with shared familiarity with Aristotle — to discuss semantic issues of concrete meaning and word use in detail, in terms both sides could in large measure agree upon. This led to a very high quality and sophistication in many contributions to the debate on both sides.

On some slight acquaintance, many modern readers can easily sympathize with nominalist critiques of the premature and illegitimate use of universals. We may think of vulgar platonism, excessive abstraction, reification, alienation, and so on. On the other side though, there are premature and illegitimate claims that universals can be explained away entirely. But Hegel’s Frau Bauer could not even recognize her individually named cows, if there were no such thing as legitimately reusable reference, naming, and vocabulary. I think most people should be able to see that there are two sides to the coin here.

If we ask how legitimate repeatabilities in ordinary language are constituted and used, something like modality inevitably comes into play. It now occurs to me that Brandom’s emphasis on the priority of hypotheticals over alleged categoricals in real-world material inference — a point to which I am deeply sympathetic — really calls for something like the notion of modality that he develops.

Meaningful “Seeing”

We ordinarily “see” things with the appearance of immediate meaning — for instance, not just patches of color but recognizable objects and individuals. We experience these as having properties that we expect to hold under various conditions that do not apply at present. We also seem to immediately apprehend subtler aspects of situations that presuppose what Kant and Hegel called “reflection” to discern and express at all. This goes far beyond any simple passive registering of sense data.

The Stoics tried to bridge the gap between a theorized passivity of perceiving and knowing and the already meaningful character of experience in a naturalistic way, by positing some kind of material transmission of “phantasms” from objects to the perceiver.

Variants of this were adopted by many Latin scholastics under the name of “sensible species”. By analogy, Aquinas and others argued for the real existence of “intelligible species” that could be passively received by the intellect.

However, medieval nominalists already anticipated modern empiricism in rejecting both sensible and intelligible species, and medieval Augustinians argued for a much larger role of active powers of the soul in the apprehension of meaning.

Kant and Hegel broadly agree with the nominalist and empiricist critique of the theory of passive transmission of species, and with an abstracted version of the Augustinian thesis of the role of active capabilities in perception and knowledge.

How this all relates to Aristotle involves many subtleties, some of which are mentioned in Aristotle on Perception.

Ockham on Reference

William of Ockham (1285-1347) is the most famous so-called “nominalist” in Latin medieval philosophy. He sought to explain our practical and theoretical uses of universals entirely in terms of our relations to existing singular things.

Without losing sight of Plato’s emphasis on the value of pure thought, Aristotle had adopted a broader perspective, starting from the generality of human life. In this context, in contrast to Plato he had emphasized the genuine importance, positive role, and irreducibility of singular beings or things that we encounter in life. “For us” singular beings and things come first, even if they do not come first in the order of the cosmos.

Singular beings and things are more concretely “real” than any generalizations about them. But Aristotle simultaneously upheld the “Platonic” view that knowledge in the strong sense can apply only to generalizations of necessary consequences between things, and not to our experiences of singulars. There can be no necessity in our experience of something purely singular. What I would call the extraordinarily productive tension between Aristotle’s fundamental views of reality (putting singulars first) and of knowledge (putting universals first) created an appearance of paradox that later commentators sought to resolve, often by favoring one side at the expense of the other.

Ockham wanted to explain universals entirely in terms of singulars. In the Cambridge Companion to Ockham, Claude Panaccio summarizes that “Ockham’s project is to explicate all semantical and epistemological features — truth values, for instance — in terms of relations between sign-tokens and singular objects in the world” (p. 58).

Ockham built on the work of many less well-known figures. The Latin world had seen lively inquiries about logic and semantics since the 12th century, when Arabic learning first began to be disseminated across Europe. Within this tradition, there is more than one approach to meaning.

The technical notion of “signification” was a development inspired largely by Augustine’s theory of “signs”. Unlike more recent usages (e.g., in Saussurean linguistics), this kind of signification involves a simple relation of correspondence between a thing taken as a “sign” and some other thing.

Ockham and many of his predecessors held that there is such a thing as natural signification, independent of any language. In this sense, smoke is taken to be a “sign” of a fire. This relation of smoke signifying fire is called “natural”, because in our experience smoke only exists where there is fire, and this has to do with how the world is, rather than with us. This is very different from the conventional imposition of the word “fire” to refer to a fire.

At the same time, this notion of signification also seems to have an irreducible “psychological” component. It has something to do with how the world is, but in a more direct sense, it has to do with something like what the British empiricists later called the association of ideas. Our “natural” association of smoke with fire is not arbitrary. As the empiricists would say, it is grounded in experience. As the Latin scholastics would say, the soul “naturally” tends to associate smoke with fire, and this is as much a truth about the soul — or about the soul existing in the world — as it is a truth about the world.

For Ockham, natural signification applies to concepts, which constitute the core of a sort of “mental language” that is in many ways analogous to spoken or written language, but is more original and does not depend on convention. Concepts on this understanding are subject to all the same kinds of syntactical relationships as individual words in speech.

In this tradition, the meaning of concepts is analyzed by analogy with the role of individual words in speech. This presupposes a view that linguistic meaning overall is founded on the meanings of individual words. The individual concepts of “mental language” that apply to individual real-world things are analogously supposed to have pre-given, natural meanings. Logic and semantics are then a sort of mental hygiene with respect to their proper use.

Ockham offers a rich analysis of connotative terms that modify the concepts corresponding to things.

Again building on the work of many authors in the Latin tradition, he develops the theory of logical “supposition”, which contemporary scholars associate with semantic discussions of reference to real-world objects. This has nothing to do with supposition in the sense of hypothesis; rather, it relates etymologically to a notion of something “standing under” something else.

Notably, Ockham and this whole tradition insist that while individual words independently have signification, only in the context of propositions or assertions expressed by whole sentences do words have the kind of reference associated with supposition. I suspect this is ultimately grounded in Aristotle’s thesis that truth and falsity apply only to whole propositions or assertions; “supposition” is to explain not just meaning, but also truth and falsity. This tradition develops a much more explicit theory of reference than Aristotle did, and the kind of reference it develops is tied to contexts of assertion, or true assertion.

The idea that reference to real-world things should be approached at the level of propositions rather than individual words or concepts has much to recommend it. But for Ockham and the tradition he continued, supposition is still fundamentally governed by signification, and signification begins with individual words or concepts. Individual words or concepts are thought to have pre-given meanings, and Ockham attempts to give this a theoretical grounding with his notion of “mental language”.

As Ockham suggests, there is a way in which notions of syntactic relations apply to pure concepts. But I take this to be an abstraction from actual usage in spoken or written language, and I don’t believe in any pre-given meanings.

Ockham’s general strong privileging of individual things over universals has a deep relation to his voluntarist and fideist theology, which owes much to his fellow Franciscan Duns Scotus. In logic, Scotus is considered a defender of “realism” about universals as opposed to nominalism, but in his theology he developed a strong notion of individuation, tied to a very radical notion of divine omnipotence that refused to subordinate it in any way, even to divine goodness (see Aquinas and Scotus on Power; Being and Representation). Essentially, from this point of view, every single thing that happens is a miracle coming directly from God, and all observed regularity in the world pertains only to a sort of divine “habit” that could be contravened at any moment.

Aquinas aimed at a sort of diplomatic compromise between this extreme theistic view that makes everything solely dependent on God, and Aristotle’s unequivocal assertion of the reality of “secondary” causes. Scotus and Ockham applied high levels of logical sophistication in defense of the extreme view.

Ockham also denied the reality of mathematical objects. Together with his extreme view on divine power, this makes very unlikely the view promoted by some scholars that Ockham in particular represented the strand of medieval thought that most helped promote the emergence of modern science. Ockham’s undeniable logical acumen was dedicated to downplaying rather than elaborating the practical importance of order in nature.

It does seem, though, that views like Ockham’s contributed to the shaping of British empiricist philosophy. Here is another chapter in the complex history of notions of reference and representation. Ockham’s very strong notion of reference as directly grounded in singular real-world objects — combined with that of the natural signification or pre-given meaning of concepts in “mental language” — helped lay the ground for what modern empiricism would treat as common sense.

For most of the 20th century, the mainstream of analytic philosophy seemed to be inseparable from a strongly empiricist direction. But Wittgenstein, Quine, Sellars, Brandom, and others have initiated a new questioning of the assumptions of empiricism from within contemporary analytic philosophy. Analytic philosophy is no longer nearly so opposed to the history of philosophy or to continental philosophy as it was once assumed to be. It is in this context that we can begin to look at a sort of Foucaultian or de Libera-esque “archaeology” of empiricism, in which Ockham certainly deserves an important place.

Nominalist Controversies

Especially in the 14th century, controversies associated with the opposition between nominalism and realism greatly exercised philosophers and theologians in the Latin West. These terms have been been variously understood, but as a first approximation, nominalism wants to deny claims about the real basis of abstractions that the realism of this context wants to affirm.

In this case, a polar opposition is concealed behind a pair of concrete terms (nominalism, realism), where in context one is understood as the simple negation of the other. As usual with debates around distinctions based on polar opposition rather than more limited and definite determinate negation, the greatest interest often lies in the way each side tries to recover something like the strong points of the other side, but in its own terms.

These controversies are worth lingering over for several reasons. For one thing, they help illustrate the great diversity, subtlety, and liveliness of medieval thought. For another, they develop many fine distinctions that are of lasting value in talking about human knowledge and understanding. We would all like to rightly apprehend things, whatever that means. The waters are commonly muddied not only by insufficient distinctions among things, but also by fundamental unclarity or ambiguity on the meaning of “existence” or “reality”, which gets worse where abstract things are involved. Who we might think was right in the debates is of secondary importance compared to clarifications of this kind. Finally, these debates involved much discussion of mental representation, its origins, and its role in thought.

Speaking with very broad brush, nominalism begins as a critique of a sort of “platonism”. Such platonism wants to say the universal is more real than the particular. It may go on to claim that abstract entities are as real as — or more real than — concrete ones. It may extend to further claims that universals simply “exist” in some pure way, independent of space and time. Nominalism in general wants to say the opposite, that universals are actually not real at all.

Aristotle already criticized platonist views of the sort just mentioned, while still maintaining that the development of universals is essential to knowledge. I think that in the big picture, he wanted to recommend an essentially even-handed approach, recognizing both universals and particulars as necessary to any developed view of experience, while pointing out their very different and complementary roles. Whatever we may think about the reality or unreality or existence or nonexistence of given things or of various kinds of things, we need universals to support the implicit reasoning standing behind any developed knowledge. We also need particulars as practical starting points, and as cross-checks to keep us honest. This does not yet make any claim about reality or existence that might support such needs. Aristotle often practiced a careful minimalism, sticking to essentials and leaving other questions open, and this is a good case in point.

Albert the Great and Thomas Aquinas wanted to develop Aristotle’s position into a firmer doctrine, classically called moderate realism. Most people agree that Aristotle thought universals do not “exist” independently of particular things and thought. Albert and Thomas argued that implicitly, what Aristotle said committed him to 1) a claim that universals are real and 2) a claim that universals exist, but only in concrete things and in thought.

Nominalists especially disputed the claim that universals exist in concrete things. They most commonly advocated a mental origin of universals, while differing on the precise status attributed to them. Already in the 12th century, Roscellinus had argued that universals are mere names (root of the word “nominalism”). Whether or not the great Peter Abelard should be interpreted as a nominalist or a middle-of-the road “conceptualist” is contested among scholars.

The theologian William of Occam (1285 – 1347) was the most famous medieval nominalist. Early in his career, he argued that universals were ficta (“fictions”) of the mind. Later, he worried that this still tacitly presupposed they were representations, which would seem to still imply something corresponding to them in external objects. He then argued that external objects have causal impact on the mind, but not by representation.

The important secular master John Buridan (1301 – 1358) is usually also called a nominalist. Buridan was one of the leading logicians of the middle ages, and wrote on a wide range of philosophical questions. He had several noteworthy students who are also considered nominalists, including the logician, natural philosopher, and bishop Albert of Saxony (1320 – 1390). Marsilius of Inghen (1340 – 1396) was another nominalist who wrote on logic, natural philosophy, and theology. The theologian Gregory of Rimini (1300 – 1358) is also considered a nominalist.

The great theologian John Duns Scotus (1265 – 1308) was a commited realist who nonetheless influenced Occam on some relatively unrelated points. The influential Walter Burley (1275 – 1344) is sometimes called an extreme realist. Paul of Venice (1369 – 1429) was formerly classed as a nominalist, but is now considered a realist.

Among those who were called nominalists, there were many different views and distinctions related to the complex medieval theories of sensible and intelligible “species”. In one aspect, these were mental representations, but theories of sensible species usually had a physical component loosely inspired by Stoicism. Occam denied species, while Buridan made use of them.

From the 12th century onward, Latin philosophers developed sophisticated original theories of the different kinds of “supposition”, or generic ways in which something said can be meant. The general notion was that the kind of supposition that should be read into a concrete utterance should be determined by analyzing the context of the utterance in various ways. This was basically a kind of semantics. What is perhaps surprising is that broadly similar supposition theories were largely shared by dedicated nominalists like Occam and commited realists like Walter Burley, providing a common vocabulary.

On a side note, Occam’s causal impact theory seems problematic from the point of view of the development here. While its avoidance of dependence on representation is attractive, a direct causal link from external objects to thoughts does not seem adequate to account for the full range of diversity of thoughts. Also, there seems to be an incipient mentalism already at work here, related to that of Avicenna.

Occam was a theological voluntarist and a fideist. Fideism is the belief that faith offers a kind of knowledge superior to reason, an extreme position that was repeatedly condemned by the Church. Occam has nonetheless often been named as a major precursor of the point of view of modern science. Even though some connections can be made, this seems questionable as well, given his mainly theological intent and the character of the theology he promoted.