The Consensus on Human Nature

Everyone talks about "human nature" like it's a settled question. It isn't.

Two thousand years of philosophy and psychology, and we still can’t agree on the basics: Are humans fundamentally rational beings who occasionally slip up? Or is something deeper going on?

Here’s the argument: across centuries and disciplines, thinkers keep arriving at the same conclusion — human nature isn’t one thing. It has three dimensions — thinking, feeling, and instinct — and the thinkers who reduce us to “rational vs. irrational” are only seeing one-third of the picture.

From Plato to Freud to modern neuroscience to the Enneagram, the three-part model keeps showing up. That pattern is worth paying attention to.

Plato is to Aristotle as Freud is to Pinker

There’s a recurring split in how great thinkers approach human nature. Some look at people and see layered complexity. Others look at people and see one defining trait — rationality — with everything else as noise.

Plato saw a layered picture. His “Tripartite Soul” described three forces constantly interacting: reason, spirit (emotion and courage), and appetite (instinct and desire). For Plato, being human meant navigating the tension between all three. No single part was the whole story.

Aristotle, his student, simplified things. He acknowledged that humans were social and that morals mattered, but for Aristotle, rationality was the defining feature. It’s what separated us from animals. Everything else was secondary to our capacity for logical thought.

This same split shows up again two thousand years later.

Freud mirrored Plato’s layered view. His model of the psyche — the id, ego, and superego — described three forces pulling at every human being. The conscious, rational mind was just the tip of the iceberg. Underneath it were drives, emotions, and moral pressures that most people never examine.

Steven Pinker, the modern cognitive scientist, mirrors Aristotle. In his book Rationality, Pinker makes a compelling case that humans have extraordinary reasoning abilities — we built science, medicine, democracy. His argument is genuine and backed by evidence. Pinker isn’t wrong that rationality is powerful. The question is whether it’s the whole picture.

Aristotle and Pinker both offer something reassuring: a clean framework. Be rational. Think clearly. The path forward is knowable. There’s an intellectual security in that — if the answer to every human problem is “think harder and more logically,” then the world is navigable.

But Plato and Freud saw something that pure rationality can’t explain. Why do smart people make terrible decisions? Why do we sabotage ourselves? Why do entire societies act against their own interests? If rationality were the whole story, none of that would happen.

Plato and Freud’s concepts side by side

The parallels between Plato and Freud aren’t vague. They map directly onto each other:

Two frameworks separated by millennia, arriving at the same architecture. That should get our attention.

But most modern discourse doesn’t start here. It starts with rationality.

The Appeal of “Just Be Rational”

Steven Pinker represents the best version of this argument. In his book Rationality, he traces how human reasoning abilities have produced extraordinary results — the scientific method, democratic institutions, declining violence over centuries. Here he is making the case:

In this clip, Pinker argues that the world is sliding toward chaos and that rationality is the cure — that human progress (science, medicine, democracy) happened because we learned to reason, and the path forward requires more of the same.

Pinker’s argument is persuasive because it’s partly true. Rationality is powerful. The problem isn’t with valuing rational thinking — the problem is with treating it as the only dimension of human nature that matters.

When rationality becomes the whole framework, every human problem gets reduced to a knowledge gap. People disagree with you? They must be misinformed. Society isn’t progressing? People need to think more clearly. Someone made a bad decision? They were being irrational.

But this framing misses something Plato and Freud both understood: the rational mind isn’t operating alone. It never was. There are forces underneath it — emotional drives, moral instincts, unconscious patterns — that shape our behavior in ways pure logic can’t access.

Why We Default to Rationality

Freud talked in great depth about his theory of the conscious and unconscious mind. He suggested that a significant portion of our mental processes occurs outside of our conscious awareness. Freud thought that the unconscious mind contains repressed thoughts, memories, desires, and unresolved conflicts that influence our thoughts, emotions, and behaviors.

A potential reason why discussions often focus on the rational aspect of the psyche, while neglecting the other parts is because the rational or conscious mind is more readily accessible and controllable. We have a direct awareness of our conscious thoughts and can easily articulate our logical ideas.

In contrast, the unconscious aspects of the psyche are not immediately accessible. It is easier to critique someone’s logic than it is their perceived morals or instincts.

By historicair - Structural-Iceberg.svg by Jordangordanier, Public Domain, Link

This isn’t just ancient philosophy. Modern neuroscience is saying the same thing.

The Iceberg in Modern Neuroscience

Andrew Huberman and psychiatrist Dr. Paul Conti, M.D. (who trained at Stanford School of Medicine) discuss this exact iceberg model on the Huberman Lab podcast. Their key point: what we’re consciously aware of — our rational thoughts — sits on top of a vast unconscious structure that drives most of our behavior. The conscious mind doesn’t run the show nearly as much as we think it does.

Huberman and Conti developed their own version of the iceberg model (view the full PDF here) that breaks down the layers of consciousness in clinical terms. The takeaway is the same one Plato and Freud arrived at: rational thought is real and valuable, but it’s only the visible tip of a much larger structure.

The Pattern That Won’t Go Away

Here’s the thing that should stop us in our tracks: the three-part model keeps showing up. Not once or twice — across completely independent traditions, separated by centuries.

Plato described it in ancient Greece. Freud rediscovered it in turn-of-the-century Vienna. Neuroscientist Paul MacLean formalized it in the 1960s with his triune brain model. And the Enneagram — which developed through an entirely separate lineage — arrived at the same structure through its three intelligence centers.

These aren’t people building on each other’s work. They’re different observers, looking at the same species, and independently finding three layers.

Four frameworks. Four different eras. Same three dimensions.

And it’s not like nobody tried other numbers. Descartes split human nature into two — mind and body. The Big Five personality model uses five traits. The Myers-Briggs uses four dichotomies. Other thinkers have proposed their own divisions. But the three-part model is the one that keeps independently re-emerging from scratch. When observers start from first principles — whether in ancient Athens, a Viennese clinic, or a neuroscience lab — they keep landing on three.

The Enneagram maps directly onto these ancient frameworks — and it goes further. It doesn’t just say “there are three dimensions.” It describes nine distinct patterns of how people prioritize these dimensions differently. Some people lead with thinking and manage fear. Some lead with feeling and manage shame. Some lead with instinct and manage anger. That’s what creates the variation in personality — not whether someone is “rational” or “irrational,” but which dimension dominates their inner life.

This reframes the whole debate. The Aristotle/Pinker view — that rationality is the defining human trait — isn’t wrong. It’s incomplete. Rationality is one-third of the picture. The people who fixate on it are usually the people for whom thinking comes most naturally. They’re seeing their own strongest dimension and assuming it’s universal.

What This Actually Means

If human nature really does operate on three dimensions, the implications are practical.

It means “just think rationally” is bad advice for two-thirds of human problems. A relationship falling apart because of unprocessed shame isn’t going to be fixed by logic. A gut-level resistance to change isn’t going to be reasoned away. The right tool depends on which dimension the problem lives in.

It means we’re talking past each other constantly. When someone who leads with thinking argues with someone who leads with feeling, they’re not just disagreeing about the topic — they’re processing reality through different channels. Neither is wrong. They’re accessing different parts of the same architecture.

It means self-knowledge requires more than intellectual analysis. You also need to understand your emotional patterns and your instinctive drives — the parts of the iceberg that sit below the waterline. That’s uncomfortable territory. It’s easier to stay in the rational mind where things feel controllable.

Which might be exactly why the Aristotle/Pinker view keeps winning the popularity contest. It’s not that rationality isn’t valuable — it is. It’s that the other two dimensions are harder to examine, harder to talk about, and harder to admit you’re governed by.

The three-part model keeps showing up because it’s true. The question isn’t whether human nature has these three dimensions. The question is whether you’re willing to look at all three in yourself — or just the one that feels safest.