First Principles Thinking

 First principles are the fundamental building blocks of an idea. They're the most indivisible part that we know to be true, and that we use to build more complex thoughts. I know this sounds a little abstract right now, but let me give you some history and analogy and an example.

Thinking from first principles isn't a new or groundbreaking idea

In fact, it's been the dominant mode of thinking among all great scientists and philosophers for a while now. It's probably the single most consistent factor among great thinkers, although there have been many practitioners of this way of thinking. I'd like to zoom in on one that you may have heard about; Aristotle.

He was a prolific organizer who believed that everything could be divided into categories and subcategories. The smallest subcategory in any domain is what we would call a first principle. He was also one of the earliest empiricists that we know; someone who believes that all knowledge is achieved through experience.

As one of the earliest major contributors to the study of biology, it makes sense that Aristotle was a first principles thinker. He would dissect animals to gain real world knowledge and then use his capacity for reason to organize and categorize the information. This cycle of seeking knowledge through experience and using reason to give its structure is how one comes to know the first principles of a subject.

Aristotle believed that we couldn’t claim to truly know something unless we understood it from its foundations — the most basic elements that everything else depends on. With that in mind, let’s shift into a more tangible analogy to explain what first principles thinking looks like in practice.

Imagine you’re trying to understand how a mechanical wristwatch works

A conventional thinker might look at the watch face, note that it tells the time accurately, maybe admire its design, and conclude that it’s “a tool that shows hours and minutes.” That’s not a wrong answer, but it’s superficial. It doesn’t tell you anything about how the watch actually functions.

A first principles thinker would approach it differently. They would remove the back case and begin studying what’s inside. They’d notice the motion of the gears, how each cog is attached to a smaller spring or tensioning component, and how those elements work together to regulate energy. They would see that every small mechanical decision — gear size, tooth shape, material tension — contributes to the accuracy of the time being shown on the face.

Instead of just identifying what the watch does, they would ask how and why each part plays the role it does. They would begin mapping how the system works as a whole — not just as a collection of parts, but as an interdependent mechanism.

At this point, the scattered observations; the “free-floating facts” — start forming a structured understanding. They’re no longer just looking at springs and screws; they’re seeing a coherent system with cause and effect.

Now compare this to someone who tries to build a watch by copying the outside only. They could replicate the dial. They could mimic the weight and casing. But without understanding how energy is stored, transferred, and regulated — without seeing how one gear drives another — their watch might look real, but it won’t keep time.

That’s the key difference.

The conventional thinker assumes surface behavior tells the whole story. The first principles thinker traces the behavior back to its origin — the inputs, the structure, the physics — and sees how it all connects.

In other words: a first principles thinker understands that precise timekeeping begins not with the hands, but with the movement. They have a deeper, more reliable form of knowledge.