How We Learned to Think in Categories

You probably didn’t choose to think in categories. You just do. So do I. So does everyone.

We sort people, objects, ideas, even feelings into neat mental buckets: smart vs. foolish, living vs. dead, natural vs. artificial, red vs. blue, friend vs. stranger. Categories make the world navigable. They’re the scaffolding of sense-making.

But they’re not neutral. And they’re not inevitable.

This essay explores how humans learned to think in categories: where the impulse came from, how it evolved, and what it does to our perception of reality.

The Origins: Pattern-Hungry Minds

Long before writing or science, early humans faced a brutal question: Is this thing safe, dangerous, edible, sacred, or cursed?

Our brains evolved to answer that question fast. Not through reasoned analysis, but through pattern recognition. If a plant with red berries made someone sick, you learned to avoid all red berries. That’s categorization in action.

It was adaptive. It helped us survive. But it also created a bias: we started expecting the world to fall into patterns, even when it didn’t quite fit.

Early Categories Were Spiritual

Before there were sciences, there were symbolic systems. Many ancient cultures organized the world not by biology or chemistry, but by sacred correspondences: earth, water, fire, air. Yin and yang. Hot and cold. Dry and wet.

Things weren’t just placed into categories—they meant something. They expressed cosmic order. To violate a category (e.g., eating something “unclean”) wasn’t just odd—it was taboo.

In this way, early classification systems were less about utility and more about meaning. They offered a story for how everything fit together.

Aristotle: The Taxonomist of Thought

Fast forward to ancient Greece, and we meet one of history’s most systematic thinkers: Aristotle. He loved categories. He wanted to sort everything—animals, ethics, logic, rhetoric, reality—into orderly hierarchies.

His system of classification influenced the Western world for centuries. Animals were grouped by characteristics (blooded vs. bloodless, walking vs. swimming). Ideas were grouped by cause (material, formal, efficient, final).

Aristotle believed that everything had an essence—a core feature that made it what it was. That belief would echo through centuries of philosophical and scientific categorization.

The Middle Ages: Categories Become Cosmic

Medieval scholars inherited Aristotle’s logic and fused it with religious doctrine. The result was a deeply hierarchical view of existence: the Great Chain of Being.

This “chain” placed everything in the universe into ranks—from rocks to plants to animals to humans to angels to God. Everything had its rightful place.

Classification wasn’t just practical—it was moral. To question the order of categories was to question divine wisdom.

The Enlightenment: Naming Everything

In the 17th and 18th centuries, science exploded. Exploration, printing, and measurement tools all accelerated. The world suddenly seemed knowable—and nameable.

Enter Carl Linnaeus, the Swedish botanist who developed the modern system of biological classification: genus, species, etc. He gave Latin names to thousands of plants and animals and turned classification into a scientific pursuit.

To name something was to know it. To sort it was to understand it. Taxonomy became a tool of reason and empire alike—used both to map nature and to categorize people.

The Dark Side of Categorization

Not all classifications are benign.

Colonial powers used categories to draw racial and cultural boundaries—declaring certain groups “savage,” “civilized,” or “scientifically inferior.” The pseudosciences of phrenology and eugenics emerged from misapplied classification logic.

The problem wasn’t categorization itself—it was the assumption that categories were fixed, natural, and value-neutral. That they revealed truth, rather than shaped it.

Modern Psychology: Schemas, Heuristics, and Bias

In the 20th century, cognitive science began exploring how our minds construct categories—not from logic, but from experience.

We form mental schemas—internal templates for understanding the world. These help us predict and act quickly. But they also lead to stereotyping, false associations, and inflexible thinking.

Terms like “implicit bias” and “cognitive distortion” describe what happens when our categories harden into blind spots.

Identity: Categories as Containers for the Self

In the past century, categorization turned inward. We now classify ourselves: introvert vs. extrovert, Type A vs. Type B, neurodivergent vs. neurotypical, creative vs. logical.

Sometimes, these labels help us understand and connect. Other times, they constrain. We begin to perform our categories—living as if the label defines the person.

Even our politics runs on identity categories: liberal/conservative, urban/rural, elite/populist. These buckets are tidy—but often too small for real people.

Can We Think Beyond Categories?

Categories are useful. Essential, even. But they’re also mental maps, not the territory.

The danger comes when we forget they’re made-up. When we treat them as immutable truths instead of provisional tools. When we build walls instead of windows.

Philosopher Ludwig Wittgenstein famously challenged the idea that categories always had hard edges. He used the example of “games”: What do chess, tag, and solitaire all have in common? Not a single feature. Just family resemblance.

Maybe the same is true of many things we try to neatly sort.

Try This: Practice “Soft Classification”

For one day, notice every time your brain makes a category-based judgment:

• That looks like a “type of person”
• That action feels “weird” or “normal”
• This idea is “smart” or “silly”

Then ask: What would happen if I blurred this boundary?

You’re not trying to reject all categories. Just to see them—and loosen your grip on them, where helpful.

Conclusion: Categories Are Tools, Not Truths

We learned to think in categories because it helped us survive. Then it helped us make sense of the world. But now, in a world defined by complexity and ambiguity, maybe it’s time to rethink how we think.

To remember that the lines we draw—between ideas, between people, between possibilities—aren’t walls. They’re sketches. Provisional. Changeable. Useful until they’re not.

After all, if we created the categories, we can reimagine them too.

This article is part of our Idea Histories trail — essays that trace how our deepest mental frameworks came to be, and how we might begin to question them.