First Principles Thinking

First Principles Thinking (also called first principles reasoning) is essentially about getting back to basics. It means breaking down a problem or idea into its most fundamental parts (the things you know are absolutely true) and then using those to solve the problem in a new way. It’s like taking apart a complex LEGO model into individual bricks, then using those bricks to build something entirely different.

This approach is considered one of the most effective strategies for generating original solutions and learning to think independently. It helps cut through the usual assumptions and habits so you can see opportunities that others might miss.

To truly grasp the power of first principles, we need to understand the default way our brains operate. Most of the time, we’re not thinking from first principles; we’re doing the opposite.

The vast majority of our day-to-day thinking is reasoning by analogy. This means we solve problems and make decisions based on what has been done before. We look at how others have solved similar problems, we follow established conventions, and we copy what seems to work.

Think of a cook following a recipe. A cook can be highly skilled, meticulously following each step to produce a delicious meal. They might even make small tweaks to improve the final dish. This is incremental improvement. It’s safe, it’s efficient, and it works well for known problems.

This is how we operate most of the time:

• We design a presentation for work using the same template everyone else uses.
• We start a fitness routine we saw in a magazine because it worked for someone else.
• A company prices its new product based on what its competitors charge.

Reasoning by analogy is our brain’s go-to method because it’s fast and requires less mental energy. It’s a fantastic tool for efficiency when you’re operating within a system that already works well. But it has a huge limitation: it makes it hard to produce something truly new. It traps you in the way things have always been done, making breakthrough innovation unlikely to happen.

First Principles Reasoning is the alternative. A first principle is a foundational truth that cannot be broken down any further. It’s a core building block of knowledge that stands on its own.

Think of a chef. A chef doesn’t just follow recipes - they can invent them. Why? Because they understand the first principles of cooking: the chemistry of how heat transforms ingredients, the science of flavor profiles (salt, fat, acid, heat), and the fundamental properties of different foods. With this deep knowledge, a chef can walk into a kitchen with a random assortment of ingredients and create something original and delicious. They are not limited by existing recipes because they can build their own from the ground up.

That is the essence of First Principles Reasoning. It’s about having the discipline to ignore the “recipe” (the conventional wisdom) and instead ask: What are the fundamental truths here?

The key is to understand that these are two different tools for two different jobs. You don’t need to use the mentally demanding first principles approach to decide what to have for breakfast. Analogy is perfect for that. But when you face a complex, important problem, or when you want to create something truly original, analogy becomes a trap. That’s when you need to learn to think like a chef.

Identify exactly what you’re trying to solve or decide. For example, “I want to save more money each month,”, “I’m not happy in my job,” or “I want to eat healthier.” Having a clear question or goal focuses your thinking.

Write down all the things you think you know about the problem and all the constraints you assume to be true. Be exhaustive and honest - some assumptions are so ingrained we barely realize we have them.

A fantastic tool for this is the Five Whys technique where you simply state your problem and ask “Why?” five times (or as many times as it takes).

Let’s walk through an example: “I want to eat healthier, but I keep failing.”

1. Why do I keep failing? Because I end up grabbing unhealthy takeout on my way home from work.
2. Why do I grab takeout? Because I’m too tired and overwhelmed to cook a proper meal when I get home.
3. Why am I too tired and overwhelmed? Because my workday is stressful, and I haven’t planned what to cook in advance.
4. Why haven’t I planned in advance? Because the idea of “meal prepping” on a Sunday feels like a huge, complicated chore.
5. Why does it feel like a huge chore? Because I’m assuming I need to plan and shop for seven different, complex, new recipes every single week.

Aha! We’ve moved from the vague problem of “failing to eat healthy” to a very specific root cause: a hidden assumption that meal prepping must be elaborate and complicated.

Once you’ve deconstructed the problem, examine each piece and determine what is an undeniable fact versus what is merely an assumption, belief, or convention.

Socratic Questioning is a great tool for this. It’s a disciplined process of asking probing questions to challenge your own thinking and uncover hidden beliefs. It forces you to provide evidence for your ideas rather than just accepting them.

Here are some example applications for our use case of eating healthier:

• Clarify thoughts: What does ‘eat healthier’ actually mean to me? More vegetables? Less sugar? Cooking at home?
• Challenge assumptions: Is it true I need to meal prep 7 full meals in advance? What if just having a couple of base ingredients ready is enough?
• Look for evidence: Do I know anyone who eats healthy with minimal prep? What do they do differently?
• Consider alternatives: What if I tried a grocery delivery service, or pre-cut veggies? Could I simplify my meals without sacrificing nutrition?
• Examine consequences: What happens if I keep believing that meal prep must be elaborate? Will I keep defaulting to takeout?
• Question the question: Why am I focused on ‘meal prepping’ as a big event? Is the real problem the complexity I’ve assigned to it, or is the core issue just having anything healthy ready to go?

Once you have your pile of fundamental truths (the “atoms” of your problem, stripped of all assumptions), brainstorm new ways to achieve your goal, as if you’re starting fresh. Ask yourself:

Knowing these fundamentals, how else could I solve this?

This is the stage to be imaginative. Combine pieces in unconventional ways. You’re essentially rebuilding the LEGO model: try out new configurations using the same blocks. Don’t worry if the ideas seem unconventional - that’s the point.

Let’s return to our healthy eating example.

The old solution: I must force myself to do complex meal prep every Sunday.

The fundamental truths:

• I want to eat according to current dietary guidelines.
• Simple, whole foods can be very healthy.
• My time and willpower are limited after a stressful workday.
• Having a pre-made option is crucial for me to avoid takeout.

The new solution: On Sunday, I will do the simplest thing possible: cook a large batch of one simple protein like grilled chicken and one simple carb like rice or quinoa. During the week, my ‘cooking’ will just involve combining these with a handful of cooked vegetables and a simple dressing. This takes 5 minutes.

Once you start looking for them, you’ll see opportunities to apply this thinking everywhere. Here are some examples.

We often follow unspoken “rules” in relationships (like “never go to bed angry” or the expectation to exchange expensive gifts on holidays) without asking why. First principles thinking can improve relationships by refocusing on fundamental needs like trust, understanding, and care.

For instance, if you and your partner are arguing constantly, step back and ask: What do we really want out of this conflict? Probably to be heard and to resolve an issue. That’s the fundamental goal. With that in mind, you might realize the method of arguing isn’t serving the goal. A different approach, like each writing down feelings calmly or taking turns speaking without interrupting might achieve the fundamental need (feeling heard) better than the inherited “fight it out” pattern.

Similarly, if gifting has become a source of stress, remembering that the core purpose is to show appreciation could inspire a simpler, more heartfelt gesture instead of an expensive purchase.

Suppose you want to stop eating junk food every afternoon. Rather than just trying the latest diet trend (reasoning by analogy - doing what others do), use first principles. Ask why you reach for snacks at that time. Are you actually hungry, or just bored or stressed? If it’s stress, the fundamental need might be relaxation or a mental break. You could satisfy that need with a short walk or a healthy smoothie instead. By addressing the core reason (stress or hunger) with an alternative, you’re solving the problem from its root, not just fighting the symptom.

Don’t just book a standard package tour (reasoning by analogy). Deconstruct the idea of a vacation into its first principles. What is the fundamental goal - relaxation, adventure, connection, or learning? What are the absolute constraints - budget, time, travel companions? From these truths, rebuild an itinerary from scratch that perfectly matches your unique desires, not a generic template.

Say you want to learn a new language and the common advice is “take this six-month class” or “memorize these vocabulary words.” If you use first principles, you’d ask what the foundational pieces of learning a language are.

You might conclude: you need to understand a certain basic vocabulary/grammar, practice regularly (immersion), and get feedback to correct mistakes. There might be faster or more enjoyable ways to get those elements than a formal class. Perhaps you find a language exchange partner online to practice speaking (covers practice and feedback) and use a fun app for the basics.

By focusing on the why behind each learning method, you can mix and match techniques that work best for you, rather than doing something just because it’s the traditional route.

This is a big life decision often influenced by tradition or peer pressure. Maybe you assume “I have to move to a big city because that’s where opportunities are” or conversely “I should stay in my hometown because it’s what I know.”

First principles reasoning would have you list what truly matters to you in a place to live (e.g. job opportunities, cost of living, climate, community, proximity to family). Weigh each factor from scratch. You might realize that with remote work available (a fundamental change in job markets), you could live in a smaller town with a lower cost of living and still have a great career.

The “right” choice might be something unconventional once you clarify your true criteria, rather than following where everyone else your age is moving.

Imagine you’ve heard that waking up at 5 AM is the key to productivity because “all successful people do it.” Before you force yourself out of bed at dawn, apply first principles. Why does early rising often help? Perhaps because it’s quiet and free of distractions. That is the fundamental benefit - not the specific time on the clock. If you’re not a morning person, you might achieve the same benefit by finding uninterrupted time at night or by minimizing distractions during the day.

In short, instead of copying someone else’s routine, focus on the core need (quiet focus time) and find a way to get that which suits your life.

In the 17th century, Isaac Newton famously watched an apple fall from a tree and wondered why it always fell straight down to the ground, rather than sideways or upward. At the time, most people would shrug and say “apples fall because that’s just what they do.”

But Newton dug deeper: why do objects fall straight toward Earth? He broke the problem down and suspected there was an invisible force at play. This basic question of treating the falling apple as a clue to a hidden fundamental truth eventually led him to develop the law of universal gravitation. He reasoned from first principles that the same force pulling the apple down might also explain the motions of the Moon and planets.

Newton’s first principles thinking transformed a simple everyday observation into one of the most important scientific laws of all time. It’s a great reminder that when we question basic facts that others take for granted, we can discover completely new insights.

In the early days of Tesla when battery packs for electric cars were extremely expensive (around $600 per kilowatt-hour) and experts assumed they’d always cost that much.

Elon Musk (Tesla’s founder) didn’t accept “that’s just the way it is.” Instead, he asked: What is a battery made of at the core? He listed out the raw materials: cobalt, nickel, aluminum, lithium, carbon, polymers, and so on. Then, he calculated that buying those components on the market would cost only about $80 per kWh in total. In other words, the fundamental cost of a battery’s ingredients was a tiny fraction of the price people were paying.

Realizing this, Musk reasoned that if Tesla could assemble batteries from the raw materials in a clever way, the price could be drastically lower. This insight led the company engineers to design new battery manufacturing methods. Over time, this first-principles approach proved correct. Battery costs fell dramatically (down to around $130/kWh by 2023, and still dropping), enabling affordable long-range electric cars.

Musk’s ability to go back to basics - treating a battery not as a pricey black-box component but as a collection of metals and parts - allowed him to innovate where others had written things off as “impossible.”