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Nominalism: The Stubble Left by Ockham’s Razor

Ockham was a methodological minimalist, not a philosophical minimalist

William of Ockham (c. 1287–1347), a Franciscan friar, was a prominent 14th-century philosopher. He taught at Oxford and other institutions in Europe. Ockham is best known for his principle of parsimony (Ockham’s Razor): “Plurality is never to be posited without necessity” and “It is pointless to do with more what can be done with fewer.”

The basic idea was not original with him, but he developed and spread it with unprecedented effectiveness.

Ockham did not say that complex metaphysical realities don’t exist. He said that we should trim our understanding of reality to the use of as few concepts as possible for reasons of efficiency, even at the cost of absolute precision. Ockham may thus be said to be a methodological minimalist, not a philosophical minimalist. He acknowledged that reality was likely a very complex matter indeed. But he insisted that we can best understand reality by paring it down to essentials and never going beyond these essentials.

In effect, he said that Christians should not use the most rigorous logic to support Christian doctrine and faith. They must instead choose the most parsimonious logic. This was in contrast to his contemporary Thomas Aquinas (1225–1274). Aquinas would undoubtedly agree with Ockham that we should not multiply explanations unnecessarily but he would also insist that we follow logic and evidence wherever it takes us, even beyond parsimony.

I think that Ockham’s razor provides a glimpse into Ockham’s soul, so to speak. His views are certainly Franciscan in flavor. The Dominicans, for whom Thomas Aquinas is the consummate example, emphasized the Divine intellect as the source of God’s actions and favored intellectual philosophical rigor, even at the expense of brevity. The Franciscans, in contrast, stressed the importance of the Divine and human will, and stressed the primacy of love over reason.

This is of course a radical generalization. Duns Scotus (1266–1308), a brilliant Franciscan philosopher and contemporary of Aquinas, was a rigorous and meticulous logician. Aquinas wrote extensively on Divine and human will and love. But the generalization expresses a truth about the Franciscan/Dominican divide that is itself a reflection of perennial styles of human knowledge. Ockham loved simplicity, true to the Franciscan spirit, but such love of parsimony led him to a profound philosophical error — the error that I think is at the root of all modernist error.

Ockham was a nominalist. Nominalism is the view that universals exist only as concepts in the mind, but not in reality. A universal is a category of being — for example, “mankind” is a universal, and “Donald Trump” is a particular. Donald Trump is a real tangible specific person, whereas mankind is a concept, of which Donald Trump is an example.

The opposite of nominalism is realism. The ancient Greek philosopher Plato (429?–347 B.C.E.) was the archetypal realist. Plato believed that abstract categories such as “mankind” are real. They really exist in the realm of Forms. In fact, Plato believed that the Forms were the ultimate reality, of which particulars merely participate in a shadowy way.

One noteworthy kind of Platonic realism was that of Augustine (354-430 C.E., left), who proposed that Platonic Forms are Ideas in the mind of God. Aristotle (384-322 B.C.E.) held to another form of realism, called semi-realism; he held that universals are real but that they exist in nature and in things, not independently in a separate realm.

Nominalists deny all of this. They propose that universals are mere categories created in the human mind, without any extra-mental reality of their own. “Mankind” is, in the nominalist view, just a way that we organize ideas in our minds.

You can see how Ockham’s passion for parsimony (and his Franciscan love of simplicity!) led him to this view: Reality is a much simpler place if we don’t bother ourselves with the realm of Forms and philosophical discourse on the Ideas in God’s Mind. And Ockham had logical reasons to deny the reality of universals. That is not to say that Ockham didn’t believe that God exists and that He held ideas comparable to universals in His Mind. But Ockham believed that metaphysics is most efficiently done without such complicating distractions as universals.

This difficulty with Ockham’s nominalism — and he was the first and most important scholastic philosopher to advocate nominalism — is that it cuts us off from any kind of reality except the reality of the senses. Over time, even that reality is in danger. Particular things — individual men and trees and rocks—can be perceived directly and Ockham was fine with that. But denying the reality of universals denies our access to knowledge and truth about things, except for knowledge about the particulars we can sense.

Ockham would say that we can create our own categories by which we understand reality, but as a nominalist he implicitly denies that our knowledge of categories has any link whatsoever to the external real world. And if we can’t know universals (because they don’t exist outside of our minds), then it’s not a big leap to doubt even our knowledge of particulars too.

Nominalism leads inexorably to Kant’s distinction between phenomena and noumena — things as they appear to our senses and things as they are in themselves. That distinction locks us into a mental theatre in which we can observe and know only projections of the world, and not anything about reality itself. This distinction between what is real and what we perceive and know is an insidious problem for us moderns, and it has its roots in Ockham’s nominalism. Nominalism also leads, inexorably, to a problem with what we can know about God.

Ockham’s razor, like his nominalism, was a destabilizing intellectual force. Parsimony is fine but truth is better. Often the move to deeper truth is the move away from parsimony. Consider the scientific advance from parsimonious Newtonian mechanics to the enormously more complex quantum mechanics and relativity, which are closer to the truth.

Ockham’s nominalism, which is of a piece with his principle of parsimony, was a virus that infected philosophy in the ensuing centuries and today is the primordial problem of modern philosophy and of modernity itself.

I’ll have more to say in due course on nominalism, and on why it is an error, why realism is true, and on how (I think) universals ought to be understood.


Further reading on nominalism: Can we engineer consciousness in a robot? One neuroscientist thinks we need only “simple guidelines.” His underlying assumptions are just wrong.


Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

Nominalism: The Stubble Left by Ockham’s Razor