First Principles Thinking: The Mental Model to Help You Think More Clearly and Accurately

personal995
May 29
5 min read

Most of us make decisions based on what seems to have worked before, copying others, following convention, or leaning on assumptions we’ve never questioned. It’s quick and saves initial mental energy, but it often leads to shallow thinking and poor choices. First Principles Thinking offers a better approach.

First Principles Thinking helps you break problems down to their core parts, question what’s really true, and build decisions from the ground up. It’s how scientists make discoveries, how great strategists cut through noise, and how clear thinkers avoid being misled by complexity or convention.

Whether you’re solving a technical problem, making a life decision, or building something new, this mental model can help you do it with more clarity, precision, and originality.

What’s in this article?

Definition of First Principles Thinking
History of First Principles Thinking
First Principles Thinking In Daily Life
Historical Example of First Principles Thinking
First Principles Thinking in Everyday Life
To Summarise
Member's Related Readings

What Is First Principles Thinking?

First Principles Thinking means breaking a problem down to its most basic, undeniable truths. And then reasoning up from there.

Instead of asking, “What’s the usual way to do this?” you ask, “What are the facts I know for sure? What can I build from that?”

It’s a way to cut through bias, tradition, or lazy reasoning. You stop relying on analogy, “because that’s how others do it,” and instead create fresh solutions by understanding the fundamental principles involved.

Some History of First Principles Thinking

Richard Feynman on First Principles Thinking

First Principles Thinking goes back to Aristotle, who described a first principle as “the first basis from which a thing is known.”

René Descartes used a similar method in philosophy, doubting everything he couldn’t prove and starting from what he could: “I think, therefore I am.” That clarity helped him build new understanding step by step.

In modern times, Richard Feynman, the Nobel-winning physicist, was known for solving problems by stripping away jargon and assumptions. He’d say, “You must not fool yourself, and you are the easiest person to fool.” Feynman learned to teach and think from the ground up, and credited that with his ability to tackle hard problems others avoided.

Feyman tells a story of how is father taught him to see the the world in this fundamental way:

He said, “It’s a brown-throated thrush. Your father doesn’t teach you much about science.” I smiled to myself, because my father had already taught me that [the name] doesn’t tell me anything about the bird. He taught me “See that bird? It’s a brown-throated thrush, but in Germany it’s called a halsenflugel, and in Chinese they call it a chung ling and even if you know all those names for it, you still know nothing about the bird–you only know something about people; what they call that bird. Now that thrush sings, and teaches its young to fly, and flies so many miles away during the summer across the country, and nobody knows how it finds its way,” and so forth. There is a difference between the name of the thing and what goes on. Richard Feynman

First Principles Thinking In Daily Life

Design a Career or Life That Fits First Principles Thinking is especially powerful when making big life or career decisions.

Instead of asking, “What job should I aim for?” or “What path is considered successful?”, you start with better questions:

Where do my skills and experiences meet the worlds needs?
What do I actually want to experience day to day?
What energizes me?
What tradeoffs am I willing to make?

You strip away prestige, pressure, or expectation, and focus on core truths: your values, strengths, constraints, and long-term goals.

This shift helps you avoid blindly copying others or chasing roles that don’t fit. You’re no longer following someone else’s playbook, you’re designing from first principles, based on how you want your life to feel and function.

It’s especially useful in fast-changing industries or if you're feeling stuck. Past norms might not apply, but the core truths about what drives you, what you can offer, and what matters to you always do.

Member's Useful link: Aspect 22: Observe

Historical Example: Feynman and the Challenger Disaster

After the 1986 Space Shuttle Challenger disaster, Richard Feynman joined the Rogers Commission to investigate. Rather than rely on surface-level reports, he went back to basics.

He asked simple questions: What materials were involved? What happens to rubber seals at cold temperatures?

Through hands-on testing (including a famous cup of ice water demonstration), he showed that the O-rings failed when exposed to cold, exactly the conditions on launch day.

While others followed layers of bureaucratic process, Feynman returned to first principles, physics, material science, testable facts. It helped uncover the real cause of the disaster and reshape NASA’s safety approach.

How to Apply First Principles Thinking to Everyday Life

Tip 1. Ask: “What do I know for sure?”

Before solving a problem, strip it down. What’s absolutely true? What are the non-negotiables? Everything else is flexible.

This helps you move from vague stress to grounded problem-solving. Whether you’re budgeting, planning a move, or starting a new habit, facts beat feelings.

Member's Useful link: Aspect 10: Focus

Tip 2. Challenge assumptions gently

You don’t need to bulldoze tradition, but you can question it. Ask: “Is this the best way, or just the default?”

This mindset often reveals low-hanging opportunities or outdated habits.

Member's Useful link: Aspect 34: Judgement

Tip 3. Rebuild from the ground up

Once you’ve cleared out false assumptions, rebuild your thinking like a scientist would. What result do you want? What inputs and processes can lead there, given what you now know?

This applies in relationships, parenting, business—even daily routines. When life gets complex, First Principles Thinking helps you reset and rebuild clarity.

Member's Useful link: Aspect 24: Knowledge

To Summarise: First Principles Thinking as a Mental Model

First Principles Thinking trains you to reason from the ground up. It helps you avoid flawed assumptions, uncover better options, and build clarity where others feel stuck.

It seems like common sense, but it's not that common.

It's more difficult. It’s not always fast, but it is more accurate.

What could you do differently, if you started from the truth instead of

initial instinct or pattern recognition?

“It is the mark of an educated man to look for precision in each class of things just so far as the nature of the subject admits; it is evidently equally foolish to accept probable reasoning from a mathematician and to demand from a rhetorician demonstrative proofs.” Aristotle