How First Principles Thinking Can Rapidly Improve Your Life

When I was nineteen, I stumbled across a blog post that changed my life.

This was my thirteenth year with type one diabetes, and up until this point, managing it had been a struggle.

I exercised regularly, ate all the ‘right’ foods, and carefully followed the guidelines I had been given when first diagnosed.

Yet, despite my best efforts, I continuously fell short.

My blood sugar levels would fluctuate which affected my energy levels and emotional state.

Managing diabetes was just plain hard, and it required tremendous amounts of willpower, self-discipline and sacrifice – and even then, you weren’t guaranteed good results.

Or at least that’s what I was telling myself at the time…

Then, one evening I was researching diabetes online and discovered a blog post from Mark Sisson. In the post, Sisson explained that insulin sensitivity was one of the keys to thriving health, and that the more sensitive you are to this hormone, the better your health would be.

This one idea hit me like a lightning bolt.

The real secret to effectively managing diabetes was to keep my body as sensitive to insulin as possible.

This was the first principle.

When I realised this, I stopped asking myself how could I better manage my condition, and instead started asking: how can I keep my body in an insulin sensitive state?

Discovering insulin sensitivity as the first principle and knowing that it was the right thing to aim at, meant I was now free to experiment with different methods for achieving it. I no longer needed to blindly follow the guidelines I was given when first diagnosed.

Over time, this led me to reducing my insulin intake from around 30 units per day to an average of 3.

I now have more energy throughout the day, more control over my blood sugars and a more stable emotional state as a result.

And this leads me to the point of this blog post:

Understanding first principles empowers you.

It frees you to be original, to think for yourself and puts you in the driver’s seat of your life. You no longer need to depend upon the tactics and strategies of others.

All tactics and strategies are aimed at achieving first principles.

They’re the means to the end. When you understand the end, you are free to experiment with different approaches for getting there.

But what exactly are first principles? And how can you uncover them in your own life?

How to Build a Rocket Ship

In a nutshell, thinking in first principles involves boiling the problem you are trying to solve down to its most basic elements.

These are the core components that everything else is built upon.

When you know what the first principles of what you are trying to achieve are, you can find alternative methods for reaching your end goal.

How Elon Musk launched SpaceX is a good example of this way of thinking in action.

When he discovered that the cost of purchasing just one rocket would be $65 million, he had to come up with an alternative approach.

“I tend to approach things from a physics framework. Physics teaches you to reason from first principles rather than by analogy. So I said, okay, let’s look at the first principles. What is a rocket made of? Aerospace-grade aluminium alloys, plus some titanium, copper, and carbon fiber. Then I asked, what is the value of those materials on the commodity market? It turned out that the materials cost of a rocket was around two percent of the typical price.”

This led Musk to a revolutionary idea.

Instead of buying one rocket (already made) for $65 million, he could buy all of the different materials required for only 2% of the price, and then hire a team to build a new rocket from scratch.

And thus, SpaceX was born.

Becoming an Original Thinker

“As to methods there may be a million and then some, but principles are few. The man who grasps principles can successfully select his own methods. The man who tries methods, ignoring principles, is sure to have trouble.”

Harrington Emerson

The example above highlights one of the key benefits of this approach:

First principles enable you to think for yourself.

When we’re trying to achieve something, we tend to look at what others in the space are doing, and then follow their approach.

The problem with this is that if there are any incorrect assumptions in their thinking, then we inherit them by default. This can cost us time, energy and take us down paths we’d have been better off avoiding in the first place.

Conversely, thinking in first principles enables you to come up with original solutions, free of the dogma and assumptions previously held in the area.

While everyone else is following the latest guru or tactic, you’ll be free to experiment with different approaches, or come up with a new one entirely.

Therefore, one of the most effective skills you can develop in today’s information overloaded world is the ability to tell the difference between first principles and assumptions.

So how do you do that?

First Principles vs Assumptions

Let’s compare examples of first principles with assumptions in two important areas of life: happiness and health.

The First Principles of Happiness

In ‘The Happiness Hypothesis, Professor Jonathan Haidt aimed to identify the core components of a happy, fulfilling life.

To do that, he spent years researching the best wisdom from ancient philosophies, religions and practices, and then put them to the test of modern scientific research.

His conclusion was that if you want lasting happiness, you should focus on getting three primary relationships right:

  1. Your relationship with your work
  2. Your relationship with the people in your life (spouse, family, friends, community)
  3. Your relationship with something bigger than yourself (e.g. a sense of purpose, the universe, God, consciousness, etc.)

Haidt argues that if you have these first principles covered, happiness occurs as a by-product.

Assumptions about Happiness

The following are some assumptions we might have about happiness:

  • To be happy, I need the approval of [insert person’s name]
  • To be happy, I need to achieve [insert goal here] e.g. make a million, get promoted, etc.

The First Principles of Health

In The Primal Blueprint, author Mark Sisson advocates an ancestral approach to health and fitness.

He argues that for optimal health, we should base our lifestyle habits around those of our hunter gatherer ancestors.

Sisson’s approach is based on the science that our bodies are very much the same as they were 200 000 years ago, which means we evolved for a very different way of life and environment than the one we currently find ourselves in.

Therefore, a first principles approach to health and fitness is to align your eating, exercise and sleeping habits with those of your ancestors. The more you can do that, the healthier you will be in the modern world.

In the book, Sisson outlines a blueprint to help you achieve this, which you can learn more about here.

Assumptions about Health

The following are some common assumptions we might have about health:

  • To be healthy, I need to follow the [X] diet (e.g. Atkins, Paleo, Vegan, Carnivore)
  • To be healthy, I need to run [X] miles every day
  • To be healthy, I need to follow the p90x workout method

Are you starting to see the difference between a first principles based approach and an assumptions-based approach?

What do first principles have in common?

First principles usually have the following characteristics:

1. They stand the test of time.

They were true (and would work effectively) one hundred years ago and are also likely to work effectively one hundred years in the future.

2. They span across multiple domains.

They are not usually confined to one area. You can apply a first principle in multiple different fields.

3. They give you flexibility in your approach.

A first principle allows you to select or design your own methods for achieving a result. Following assumptions, on the hand, leads to a more rigid approach.

4. They are falsifiable.

First principles are usually based on a statement that can be proved wrong.

How to Uncover First Principles

In his book: The Great Mental Models’, Shane Parrish explains that one of the most effective ways to uncover first principles is to get back in touch with your 4-year-old-self.

When you were that age, how did you find out about how the world worked?

The question ‘why’ was probably your primary tool of inquiry.

When someone told you something, you asked why. When they gave you an answer, you asked why again. When they gave you an answer to that, you asked why again.

And you kept doing it until you were asked to stop…

We’re born with a deep, innate curiosity and desire to understand how the world works. We asked why so much because we knew instinctively that it would keep getting us closer to the truth.

However, as we get older, we lose touch with this innate curiosity and desire to question things.

We increasingly take on the assumptions and beliefs of the people around us and assume them to be true.

Therefore, one of the best ways to uncover first principles, is to get back in touch with your 4-year old self and ask why 5 times.

If your whys result in a statement of falsifiable fact, you have hit a first principle.

If they land on a ‘because I said so’ or ‘that’s the way it is’, then you know you have landed on an assumption.

Although this method may slow you down in the short term, it can help you cut through faulty assumptions, uncover first principles and come up with original solutions that save you valuable time and effort in the future.


“If [more] information was the answer, then we’d all be billionaires with perfect abs.”

Derek Sivers

We live in an age of information overload.

For anything you want to achieve, there are hundreds, if not thousands, of different tactics out there.

Therefore, learning how to think in first principles is one of the most powerful skills you can develop.

If you can do this, it puts you in the driver’s seat of your life.

While everyone else is blindly following the latest guru or tactic, you’ll be flexible in your approach and free to experiment with different methods for achieving your end goal.

You might even come up with your own unique solutions.

How do you apply first principles thinking in your life?

Leave a comment below and let me know.

Picture of Niall McKeever

Niall McKeever

Writer and Founder of The Weekend University. Passionate about making great ideas more accessible.

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One Response

  1. Hi Nick,

    I have an autoimmune disease called Takayasu’s arteritis, also called Pulse-less disease.
    This has forced me to think in First Principles too. I didn’t even know I was thinking in First Principles until I came across certain blogs like yours.

    My First Principle is: Heal the mind with Honesty/Truthfulness/Authenticity/Integrity and the rest will automatically follow, in the way it wants to.

    Felt happy reading your progress using the right approach. Keep it up.
    God bless you. 🙏😊

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