First Principles Thinking

What is it?

First principles thinking means breaking a problem down to the most basic facts you know are true, and building your answer back up from there, instead of copying what everyone else does.

Most of us think by analogy. We look at what others are doing and copy it, with small changes. First principles thinking is different. You ask:

"What do I actually know for sure here? Forget assumptions — what are the raw facts?"

Then you rebuild your solution from those facts.

A simple way to picture it

Think of a problem like a tree.

• The leaves are opinions, trends, "how things are usually done."
• The roots are the basic truths physics, math, cost, human needs things that don't change.

Most people argue about leaves. First principles thinking means going down to the roots.

Example 1: Elon Musk and rocket costs

Everyone said rockets are expensive because that's just how much rockets cost that was the "copy others" answer.

Musk asked instead: What is a rocket actually made of? Aluminum, titanium, copper, carbon fiber. He priced out the raw materials.

Turns out the raw materials were only about 2% of the price people were paying. So the high cost wasn't a law of nature it was just how the industry always did it. That's why SpaceX started building rockets themselves instead of buying them at the "normal" price.

Example 2: Cooking

Say you want to make a sauce but don't have the exact recipe.

• Analogy thinking: "I don't have the recipe, so I can't make it."
• First principles thinking: "What does a good sauce actually need? Fat, acid, salt, and something to build flavor (onion, garlic, herbs). I have butter, lemon, salt, and garlic I can make something good."

You're not copying a recipe. You're using the basic truths about what makes food taste good.

How to actually do it (3 steps)

1. Ask "why" until you hit bedrock. Keep asking why something is the way it is, until you reach a fact that's just true not an opinion or tradition.

2. List only what you're 100% sure of. Throw out assumptions, "common knowledge," and "that's how it's always done."

3. Rebuild from scratch. Using only the true facts, construct a new answer. It might look nothing like the "normal" way and that's fine.

Why it matters

• It helps you solve problems nobody else has solved, because you're not just copying old solutions.
• It helps you question habits and beliefs that don't actually make sense anymore.
• It makes you harder to fool, because you're reasoning from facts, not from "everyone says so."

One-line takeaway

Don't ask "how has this always been done?" Ask "what is actually true here?, then build up from that.