Consider a plate—any plate you've ever held or seen. While each individual plate differs in material, shape, and size, something profound unites them all: their essential "plateness." Before any specific plate could be crafted, the very concept of what makes a plate a plate had to exist. This observation opens the door to one of philosophy's most consequential debates: the problem of universals.
The Realists, led by luminaries like Anselm of Canterbury, argued that these universal concepts aren't mere human constructs but exist as real entities. It provided the foundation for understanding how knowledge itself is possible. When we recognize a plate as a plate, we're not just applying an arbitrary label, we're recognizing a real universal structure that exists independently of our minds.
The Nominalist Challenge
The Nominalist movement, which gained significant momentum in the later Middle Ages, presented a formidable challenge to Realist thought. Led by influential thinkers like William of Ockham (1285-1347) and Roscelin of Compiègne (c. 1050-1125), Nominalists argued that universal concepts were merely names (nomina) or useful fictions—convenient labels we attach to groups of similar things, but nothing more. For them, only individual, particular things truly existed.
Roscelin, often considered the father of medieval Nominalism, went so far as to declare that universal concepts were merely "flatus vocis" (puffs of air)—just sounds we make with our voices, devoid of any real existence. This radical position earned him considerable controversy, especially when he applied this thinking to religious concepts like the Trinity.
William of Ockham, perhaps the most sophisticated Nominalist thinker, developed a more nuanced position. He argued that while universal concepts might exist as mental concepts (conceptus mentis), they had no reality outside the mind. His famous principle of parsimony—"Ockham's Razor"—suggested we shouldn't multiply entities beyond necessity, leading him to reject the existence of universal forms as unnecessary metaphysical baggage.
The Nominalists gained particular strength in the 14th century, with thinkers like Jean Buridan and Nicolas of Autrecourt joining their ranks. They were often associated with the "via moderna" (the modern way) in contrast to the "via antiqua" (the ancient way) of Realism. Their approach appealed to those seeking to break from traditional authorities and emphasize direct observation of particular things—a tendency that would later influence the development of empirical science.
The Nominalist approach had significant practical implications. Their insistence that only particular things existed led them to emphasize direct observation over abstract theorizing. However, as we'll see, this apparently practical approach ultimately creates more problems than it solves, leaving us unable to explain the remarkable success of scientific generalizations and mathematical reasoning.
The Three-Layered Architecture of Reality
Thomas Aquinas developed perhaps the most sophisticated defense of Realism through his brilliant three-layer theory of universals. This framework explains how universal concepts exist simultaneously at different levels of reality:
Ante Rem (Before Things): Universal concepts exist first in the divine intellect as perfect archetypes. These aren't just abstract possibilities but the actual blueprints of reality. Just as an architect's plans precede a building, these universal forms precede their particular instantiations.
In Re (In Things): Universals exist within actual objects as their essential nature. When we encounter any particular thing—whether it's a rose, a triangle, or an act of justice—we're encountering both its individual characteristics and its participation in a universal form. This explains why we can recognize different instances of the same type despite their individual variations.
Post Rem (After Things): Finally, universals exist as concepts in the human mind, abstracted from our experience of particular things. This explains how we can form reliable knowledge about categories and types, rather than just collecting disconnected observations of particulars.
Why Science Needs Realism
Modern science, far from disproving Realism, actually depends on it in ways that many fail to recognize. When scientists formulate natural laws, they're not merely creating useful fictions, they're discovering real patterns in nature. The remarkable success of scientific prediction makes no sense unless scientific theories are capturing genuine universal structures in reality.
Consider quantum mechanics: while individual quantum events may be probabilistic, the mathematical structures that govern them are perfectly universal and precise. This is exactly what we would expect if universal mathematical structures were real features of the universe, not just human constructs.
The Logical Necessity: Scotus's Unanswerable Challenge
John Duns Scotus was an important medieval philosopher and theologian. He was known as the "Subtle Doctor" due to the precise and nuanced nature of his philosophical arguments. He was a Franciscan friar who taught at Oxford, Paris, and Cologne. Scotus provided several devastating arguments against Nominalism that remain powerful today.
The Problem of Similarity: If everything is purely individual, how do we explain real similarities between things? Two white swans are similar in both their "swanness" and their whiteness. Without real universal natures, this double similarity becomes inexplicable.
The Paradox of Pure Individuality: If there were only individual things with no universal natures, then the very fact that all things share the characteristic of being individual would itself be a universal—creating a self-contradiction in the Nominalist position.
The Ineffability of the Individual: Pure individuals, Scotus argued, are actually unspeakable, because any concept we use to describe them already implies universality. This shows that universal concepts must be real, as they're necessary even to think about individuals.
The Unity of Classification: Scientific classification would be impossible if things weren't united by real universal natures. The fact that we can recognize natural kinds suggests that universals are real features of the world, not just convenient fictions.
Why This Matters
The Realist position has profound implications that extend far beyond abstract philosophy. Consider first how it transforms our understanding of scientific research: if universal laws and categories are real, science becomes a process of discovery rather than invention. This explains why scientific theories so often reveal unexpected connections and predict previously unknown phenomena. Similarly, the famous observation by physicist Eugene Wigner about the "unreasonable effectiveness of mathematics" in describing nature makes perfect sense if mathematical structures are real features of the universe rather than human constructs.
The implications reach into the moral realm as well: moral truths can have objective standing if universal values are real rather than mere social conventions, providing a solid foundation for ethical knowledge and moral progress. This understanding transforms our view of knowledge and learning too—the very possibility of genuine knowledge depends on there being real universal structures to know, which explains why education can be more than just learning conventions; it can be genuine discovery. Even our technological advancement rests on this foundation, as our ability to create new technologies depends fundamentally on the reality of universal natural laws that can be understood and applied in novel ways.
Conclusion: The Triumph of Reality
The medieval Realists were protecting our ability to understand reality itself. Their sophisticated defense of universal structures provides the most coherent foundation for understanding both scientific and moral truth. Sadly our world today is dominated by relativism and subjectivity, it's time to recognize that those medieval thinkers glimpsed something profound: universal concepts are real features of an objective world waiting to be discovered.
The debate over universals is the key to understanding how knowledge, science, and ethics are possible at all. The Realist position, far from being outdated, provides the most coherent foundation for understanding both the remarkable success of modern science and the possibility of objective truth in all domains of human inquiry.