What Does It Mean When Words Don't Mean the Same Thing? Medieval Theories of Analogy

You know how sometimes you use the same word to talk about two very different things, and you know it’s not an accident? Like when you say that your friend’s dog is “healthy,” and then you say that the food you feed it is “healthy,” and then you say that the way it looks—bright eyes, shiny coat—is a “healthy” sign. You’re using the same word, but you don’t mean the same thing. The dog actually has health inside it. The food causes health. The bright eyes are a sign of health. Three different meanings, but they’re all tied together somehow.

Now imagine a harder puzzle. Suppose you want to say that God is good, and your friend Sarah is good. Are you using “good” the same way? Sarah’s goodness is limited—she’s good at some things, not others, and sometimes she’s selfish. God’s goodness, if you believe in God, is unlimited and perfect. Can the same word really apply to both? And if it can’t, how can we even talk about God at all?

This is the kind of question that drove medieval philosophers to develop a theory of something they called analogy. It’s a strange word that shows up at the intersection of logic, theology, and metaphysics. And the arguments they had about it—about whether words like “being,” “good,” and “healthy” work the same way, and about how many meanings a word can have before it breaks—still matter today, not just for religious thinkers but for anyone who wonders how language connects to reality.

The Basic Problem: One Word, Many Meanings

Medieval philosophers thought about language in a particular way. They believed that spoken words (like “dog” or “healthy”) were arbitrary—we just decided to make those sounds. But the concepts those words connected to in our minds were natural. All humans with similar experiences would form the same concepts, just by thinking about the world.

The tricky part came when one word seemed to connect to more than one concept. Aristotle, the ancient Greek philosopher whose work was the foundation of medieval education, had pointed out two basic possibilities.

Sometimes a word is univocal—it means exactly the same thing every time you use it. When you call your neighbor’s dog “animal” and a wolf “animal,” you’re using the word to pick out the same kind of thing: a living creature that moves and senses and breathes. Same concept, different individuals.

Sometimes a word is equivocal—pure coincidence that the same sound means different things. When you say “bank” (where you put money) and “bank” (the side of a river), those are just two different words that happen to sound the same. Medieval philosophers called this “chance equivocation” and gave the example of “canis,” which in Latin could mean a barking dog, a sea creature (a dogfish), or a constellation (the Dog Star). Same sound, totally unconnected meanings.

But what about words like “healthy”? It’s not pure chance—the meanings are obviously connected. And it’s not exactly the same meaning either. “Healthy” seemed to fall somewhere in between. Medieval philosophers called this kind of in-between term analogical.

The Three Kinds of Analogy

By the thirteenth century, philosophers had worked out a standard way of classifying analogical terms. They identified three types, all involving a “prior and posterior” sense—meaning that one use of the word is basic, and the other uses depend on it.

Analogy of Attribution: “Healthy”

The most discussed example was “healthy.” When you call an animal healthy, you mean it actually possesses health. When you call food healthy, you mean it causes health in an animal. When you call urine healthy, you mean it signals health in an animal. The animal’s health is the primary meaning; everything else is defined by its relationship to that primary case.

This kind of analogy is called “attribution”—you’re attributing healthiness to different things based on how they relate to the one thing that really has health. Notice that the definition of “healthy food” literally includes the idea of a healthy animal. You can’t explain what healthy food is without mentioning animals getting health from it.

Analogy of Proportionality: “Principle”

A second kind of analogy involved comparing relationships. Consider the word “principle” (in Latin, principium). You might call the number 1 a “principle” of counting, and a point a “principle” of a line, and a heart a “principle” of an animal, and a source a “principle” of a river. What do these have in common? Not a shared nature—numbers, lines, hearts, and rivers are completely different kinds of things. But there’s a similarity in the relationship: each is the starting point for something else. 1 is to number as point is to line as heart is to animal as source is to river.

This is analogy of proportionality. The meaning of “principle” shifts because the relationships are similar, even though the things themselves are totally different.

The Special Case of “Being”

The most important and difficult case was the word “being” itself. Everything that exists is a being—you, your backpack, the number seven, the color blue, a thought about pizza. But these don’t all exist in the same way. You exist as a substance (a thing that can exist on its own). The blue of your backpack exists as a quality (it depends on the backpack to exist at all). The number seven exists as a mathematical object (maybe in a different way entirely).

When you say “your backpack exists” and “blue exists,” are you using “exists” in the same sense? Medieval philosophers were deeply divided. Some thought “being” was analogical—all the meanings are tied together, but they’re not identical. Others thought it was univocal—there’s one core meaning of “exists” that applies to everything. And a few thought it was purely equivocal—just a coincidence that we use the same word for such different kinds of existence.

Thomas Aquinas and Talking About God

The most famous treatment of analogy comes from Thomas Aquinas (1225–1274), a Dominican friar who spent his career trying to reconcile Christian theology with Aristotle’s philosophy. Aquinas’s problem was this: Christians wanted to say positive things about God—that God is good, wise, powerful, and so on. But they also believed that God is completely different from anything in creation. God doesn’t have a body. God doesn’t exist in time. God is simple (no parts or properties that could be separated from each other). So how can human words, which were invented to describe created things, possibly apply to God?

Aquinas argued that the words we use for God can’t be purely equivocal—if they were, we couldn’t make any meaningful claims about God at all. “God is good” would be just a random sound. They also can’t be purely univocal—if they were, we’d be saying God is good in exactly the same way your friend Sarah is good, which would make God seem limited and creaturely.

So the words must be analogical. When we say “God is good,” we’re using “good” in a way that’s related to but different from “Sarah is good.” The relationship is one of cause and effect. God is the source of all goodness. Sarah’s goodness is a limited participation in God’s infinite goodness. So “good” applies to God first (in a prior sense) and to creatures second (in a posterior sense), because God’s goodness is the original that creatures copy imperfectly.

Aquinas made a subtle move here. He distinguished between the thing signified by a word (the what-it-is) and the mode of signifying (the how-we-say-it). When we say “God is good,” the thing signified—goodness itself—really does apply to God. But the mode of signifying—the way our language implies time, composition, and limitation—does not. So we have to use analogical language, always aware that our words point beyond themselves to a reality they can’t fully capture.

John Duns Scotus: A Challenge to Analogy

Not everyone agreed with Aquinas. John Duns Scotus (1266–1308), a Scottish Franciscan, thought the whole idea of analogy was confused. Scotus argued that for a term to function in logical arguments—the kind of arguments philosophers and theologians use to prove things—it has to be univocal. If “being” or “good” means something different when applied to God and creatures, then any argument that moves from creatures to God would commit the fallacy of equivocation. It would be like arguing “dogs bark, bark is a tree covering, therefore dogs are tree coverings.”

Scotus’s solution was bold: he claimed that words like “being” are actually univocal. There is one concept of being that applies to everything—God, you, your backpack, numbers, everything. This doesn’t mean that God and creatures share some nature (Scotus was clear that they don’t). It just means that our mind can form a single concept that covers all cases. We can grasp that something is a being without knowing whether it’s finite or infinite, substance or accident. That ability, Scotus argued, shows that “being” is univocal.

This sparked a huge debate. If “being” is univocal, then we can do theology and metaphysics with clear concepts and valid arguments. But does that mean we’re missing something important about the radical difference between God and creatures? Many theologians thought Scotus went too far.

The Nominalist Response

A third position came from philosophers called nominalists, especially William of Ockham (1287–1347) and John Buridan (1300–1361). The nominalists were suspicious of any entities that weren’t strictly necessary. They thought that if you said “being” is analogical, you were multiplying concepts unnecessarily. They argued that analogical terms were really just equivocal—they had two different concepts associated with them. “Healthy” as applied to animals and “healthy” as applied to food aren’t really the same word with a stretched meaning; they’re two different meanings that happen to be related through causal connections.

For the nominalists, words like “good” when applied to God and creatures were either metaphorical (and so not literally true) or else they were univocal (and so applied in the same sense). There was no real middle ground. This position had the virtue of clarity, but it made it harder to explain how we could make literally true statements about God.

Why This Still Matters

You might wonder why anyone cares about these medieval debates. But consider: every time you use a word—“healthy,” “good,” “true,” “real”—you’re relying on some theory about how that word relates to the world. Are you saying the same thing every time? Or are you stretching the meaning? And how do you know?

The medieval theory of analogy is, at bottom, a theory about how language can be flexible without breaking. It’s about how we can use the same word to capture real connections between different things, without pretending those things are identical. It’s about how we talk about things we can’t fully understand—whether that’s God, or consciousness, or the color red, or what it means for something to be “fair.”

The philosophers who argued about analogy were trying to answer a question that never goes away: does language capture reality, or does it just organize our thoughts? Their answer was that it does both—and the relation between the two is where all the interesting puzzles live.

Appendices

Key Terms

Term	What It Does in This Debate
Signification	The basic job of a word: making known something beyond itself (a concept or a thing in the world).
Univocal	A word that means exactly the same thing in every use; one concept for one word.
Equivocal	A word that means different, unrelated things in different uses; multiple concepts for one sound.
Analogical	A word that means different but related things; the meanings are connected but not identical.
Prior and posterior	A way of ranking meanings: the “prior” sense is basic, and the “posterior” sense depends on it (like healthy animal vs. healthy food).
Analogy of attribution	One kind of analogy where secondary meanings are defined by their relation to the primary meaning (e.g., food causes health, urine signals health).
Analogy of proportionality	Another kind of analogy where the similarity is in the relationships between things, not in the things themselves.
Ratio/concept	A mental representation—what you grasp when you understand a word.
Mode of signifying	How a word presents what it means—including things like time, gender, and whether it’s abstract or concrete.

Key People

Aristotle (384–322 BCE): Ancient Greek philosopher whose works on logic and metaphysics were the foundation of medieval education. He identified the basic categories of equivocal, univocal, and what later thinkers would call analogical terms.
Boethius (480–524 CE): Roman philosopher who translated Aristotle’s logic into Latin and wrote commentaries that shaped medieval thinking about language. His division of equivocal terms became the standard starting point.
Thomas Aquinas (1225–1274): Dominican friar who tried to reconcile Christian theology with Aristotle. He used analogy to explain how human words can apply to God, arguing that God is the “prior” sense of perfections like goodness.
John Duns Scotus (1266–1308): Franciscan philosopher who argued that “being” is univocal—one concept that covers everything from God to rocks. He thought analogy made logical arguments impossible.
William of Ockham (1287–1347): Franciscan philosopher who argued against multiplying unnecessary entities. He thought analogical terms were really just equivocal in disguise.

Things to Think About

When you say “this is a fair game” and “this is a fair teacher,” are you using “fair” in the same sense? If not, how are the meanings related? Is one more basic than the other?
Scotus argued that we can form a concept of “being” that applies to everything, without knowing whether something is finite or infinite. Do you think that’s true? Can you really think “this something exists” without having any idea what kind of thing it is?
What about words like “real”? Is a real tree and a real memory both “real” in the same way? What about a real number and a real friendship? Do you think we need analogy to connect these, or can we find one core meaning?
If you were trying to explain something you believe in but can’t fully describe (maybe God, or consciousness, or the feeling of being in love), would you need analogical language? Or could you find exact words?

Where This Shows Up

Everyday arguments about words: When someone says “you’re using that word wrong” and you say “I’m using it in a different sense, but it’s related,” you’re having a debate about analogy.
Science and mathematics: Scientists talk about “energy” in different but connected ways (kinetic, thermal, chemical). Mathematicians talk about “number” covering whole numbers, fractions, and imaginary numbers. These are analogical extensions.
Religious and philosophical discussions: Debates about whether we can talk meaningfully about God, or about consciousness, or about abstract objects like numbers, often turn on whether the words we use are univocal or analogical.
Translation and cross-cultural communication: When you try to translate a word from another language that doesn’t have an exact match in English, you have to ask: is this analogy of attribution, or proportionality, or something else entirely?