Introduction
First principles reasoning (also called first principles thinking) is a problem-solving approach that involves breaking problems down to their most fundamental truths and building solutions from the ground up . It means separating what is absolutely true about a problem from all assumptions, and then using those basic truths as the foundation for decision-making or innovation . This approach has been used by great thinkers throughout history – from ancient philosophers like Aristotle and René Descartes to modern innovators like Elon Musk – to question conventional wisdom and spur breakthrough ideas. Over two millennia ago, Aristotle defined a first principle as “the first basis from which a thing is known” , emphasizing that true understanding must start with fundamental truths. In essence, reasoning from first principles requires identifying the core facts or elements of a situation that are beyond doubt, then using those elements to reconstruct new solutions from scratch, rather than defaulting to what has been done before.
What Does It Mean to Reason from First Principles?
Reasoning from first principles is often described as “thinking like a scientist.” Instead of taking anything for granted, one starts with basic questions: What do we know for sure? What has been proven true? All complex problems are treated as assemblies of smaller components, and the goal is to reduce a problem to its fundamental parts or truths. A first principle, by definition, is a basic assumption that cannot be deduced any further . By continually asking “why?” or digging deeper into why things are the way they are, you peel away layers of assumptions until you’re left with bedrock truths. The French philosopher Descartes famously exemplified this approach with his method of systematic doubt: he “doubted everything he could possibly doubt until he was left with what he saw as purely indubitable truths” – the most famous being “I think, therefore I am.” Starting from that first principle, Descartes attempted to rebuild a foundation of knowledge. In practice, you don’t always need to break every problem down to the atomic or existential level to benefit from first principles thinking. Often, going just “one or two levels deeper” than usual yields new insights . By identifying the elemental facts of a situation – the things you are sure are true – you set the stage to derive fresh ideas or approaches that others might miss.
For example, consider a thought experiment by strategist John Boyd: imagine a motorboat, a tank, and a bicycle, then break each into its components (a boat’s motor and skis, a tank’s metal tracks and armor, a bike’s handlebars and wheels) . If you forget the original products and focus on these fundamental parts, you could recombine them into something new – Boyd suggested a snowmobile – by mixing pieces from each . This playful scenario illustrates first principles reasoning in action. It’s a cycle of deconstruction and reconstruction: you deconstruct a situation into core pieces and then reassemble those pieces in a more effective or innovative way . By resetting everything to the basics, you escape the confines of how things are usually done.
Why Is First Principles Thinking Valuable?
Reasoning from first principles is powerful because it unlocks original solutions and breakthrough innovations. Instead of making superficial tweaks to existing ideas, first principles thinking can reveal fundamentally better ways of doing things. As one source puts it, “First principles thinking is one of the most effective strategies for breaking down complicated problems and generating original solutions” . The method forces you to confront what is actually possible, rather than what everyone assumes. By questioning assumptions and going back to basics, you may uncover opportunities that are hidden when we simply follow convention. In short, first principles thinking moves you away from incremental improvements and opens up entirely new possibilities .
Another key benefit is that it helps you think for yourself instead of copying others. It’s easy to fall into mental ruts by doing things a certain way just because that’s how they’ve always been done. First principles analysis cuts through this inertia. If we never learn to take something apart and challenge our assumptions, “we end up bound by what other people tell us is possible” . By contrast, first principles thinkers actively resist being limited by outdated or unexamined beliefs. This kind of thinking can be crucial when conditions change or when facing novel problems – it allows you to adapt and find solutions outside the usual playbook . Many transformative ideas in history emerged when someone decided to ignore the prevailing “rules” and rethink the problem from scratch.
Importantly, building knowledge on first principles also leads to deeper understanding. Nobel-winning physicist Richard Feynman, for example, lamented that many people “don’t learn by understanding; they learn by some other way… Their knowledge is so fragile!” . Knowledge built on rote memorization or analogy can crumble when conditions change, but knowledge built on first principles is more robust. By understanding why things are the way they are at a fundamental level, you can better troubleshoot issues and adjust to new situations. In fields from science to entrepreneurship, a firm grasp of first principles ensures that you’re standing on solid ground. As one author notes, “understanding the first principles of your field is a smart use of your time” because without a firm grasp of the basics, it’s hard to master the finer details or innovate meaningfully . In summary, first principles thinking is valuable because it promotes creativity, independence, and clarity – it equips you to solve problems in ways that others might never consider .
First Principles vs. Reasoning by Analogy
It’s helpful to contrast first principles reasoning with the far more common approach: reasoning by analogy. When we reason by analogy, we make decisions based on precedent – we look at how others have done it or how it’s been done before, and we make “slight iterations on a theme” . In other words, analogy means copying or tweaking existing ideas instead of genuinely examining whether those ideas are the best way. As Elon Musk famously pointed out, “through most of our life, we get through life by reasoning by analogy, which essentially means copying what other people do with slight variations” . This kind of thinking is the default for everyday decisions because it’s fast and cognitively easy – you’re following known paths. However, it can also trap you in incremental improvements and inherited assumptions.
By analogy, if someone hands you a small toy house built from LEGO bricks, you might reason by analogy and simply rearrange a few bricks to improve it. Your changes would be minor because you’re accepting the given structure. First principles thinking, by contrast, would have you take the house completely apart into individual LEGO pieces, and realize you could build something entirely different – perhaps a bridge or a spaceship – not just a slightly better house . Most people stop at the first approach (tinkering with the existing model), whereas first principles thinkers see the raw components as building blocks for any design. This illustrates how first principles reasoning frees you from the original analogy and lets you conceive radically different solutions.
A real-world example of analogy vs. first principles is the history of travel luggage. For centuries, travelers carried suitcases and bags in their hands. Innovators kept trying to make a “better bag” – using stronger materials, adding pockets or straps – but the basic form (a box or sack carried by hand) stayed the same . Wheels were widely used on vehicles since ancient times, yet nobody thought to combine the bag and the wheel for an extremely long time . This is because everyone was reasoning by analogy: “a suitcase is something you carry,” so they focused on improving handles and straps. It wasn’t until 1970 that Bernard Sadow, stuck lugging heavy bags in an airport, asked a different question: what is the real goal here? It’s to move things efficiently from point A to B. With that first-principles focus on the core function (moving stuff), the solution emerged: put wheels on the suitcase . The rolling suitcase was born, and it revolutionized travel gear. In hindsight it seems obvious, but it was missed because everyone had been fixated on the existing form (a carryable bag) rather than the underlying need (portable transport of belongings). As one analysis quipped, “what looks like innovation is often an iteration of previous forms rather than an improvement of the core function” . The first-principles thinker abandons loyalty to the old form and instead optimizes for the function or goal itself .
Elon Musk offers a similar observation with the question, “Where are the flying cars?” People who ask that, he notes, are imagining a car with wings – they’re tied to the form of a car. But if the real goal is airborne transportation, we already have “flying cars”: they’re called airplanes . This highlights Musk’s point that many of us “live life by analogy”, sticking to traditional forms and ideas . First principles thinking, in contrast, invites us to “abandon [our] allegiance to previous forms” and focus on the result we want to achieve . In practice, reasoning by analogy tends to produce continuous, incremental improvement within an established framework, whereas reasoning from first principles can set you on a different trajectory altogether . Both approaches have their place – analogy can be useful when speed is needed or when a problem is well-understood. But for truly novel, transformative solutions, first principles reasoning is often the key. It requires more mental effort (Musk notes that reasoning from first principles “takes a lot more mental energy” than going by analogy ), but it enables breakthroughs that analogy-bound thinking would never permit.
Historical Foundations of First Principles Thinking
Aristotle: Origins of First Principles in Philosophy
The concept of first principles has deep roots in philosophy, especially in the work of Aristotle. Aristotle believed that every field of knowledge and every logical argument must ultimately rest on foundational truths that do not themselves depend on any deeper proof. In his Metaphysics, he wrote that the starting point of understanding is identifying these primary truths – as noted earlier, “the first basis from which a thing is known.” In practice, Aristotle and his teacher Plato were searching for knowledge that was certain and could serve as a secure basis for further reasoning . Aristotle held that by deducing conclusions from the right first principles, one could attain scientific knowledge (episteme). For example, in his approach to logic and science, he emphasized finding self-evident axioms or postulates about a subject and then building up knowledge by reasoning from those axioms. This Aristotelian emphasis on first principles laid the groundwork for the deductive systems in geometry and the scientific method centuries later. The influence is clear: even today, when we “go back to first principles,” we are following a path that Aristotle illuminated – starting from what is fundamentally true and reasoning forward from there.
René Descartes: Cartesian Doubt and Fundamental Truths
In the 17th century, René Descartes carried the first principles approach into modern philosophy and early science. Confronted with a world of uncertain beliefs and potential illusions, Descartes decided to wipe the slate clean and rebuild knowledge from scratch using only absolutely certain truths. He employed what is now called Cartesian doubt: he “systematically [doubted] everything he could possibly doubt” until he arrived at a truth that was unquestionable . That truth was the famous realization “Cogito, ergo sum” – “I think, therefore I am.” No matter what else could be false or deceiving, Descartes concluded that the very act of doubting proved the existence of his own mind as a thinking entity. This became the first principle of his philosophy. From there, Descartes attempted to reason outward to establish the existence of God, the reality of the external world, and so on, using logic and clear definitions.
Descartes’ exercise was essentially first principles reasoning applied to epistemology (the theory of knowledge): he stripped away every inherited assumption and accepted belief, and started from an indubitable starting point to derive new knowledge. His approach illustrates the courage and rigor of first principles thinking – it was valuable in questioning dogma, notably challenging the scholastic teachings of his time, and it contributed to the development of the scientific method. In science, Descartes also applied systematic reasoning from basic principles in areas like analytical geometry and optics. While not all of Descartes’ conclusions stood the test of time, his method of thinking from first principles remains a cornerstone of rational inquiry. Philosophically, it showed that sometimes progress can only be made by questioning everything down to the foundations – a hallmark of first principles reasoning.
Modern Examples Across Different Domains
First principles reasoning is not just a philosophical exercise; it’s alive and well in modern science, engineering, business, and design. Let’s look at how this mode of thinking appears in various domains and contemporary examples:
Physics and Science: Grounding Ideas in Fundamental Laws
In the realm of physics and science, reasoning from first principles is virtually a default approach. Scientists seek to explain phenomena by tracing them to underlying laws of nature. Instead of relying on analogies or purely empirical correlations, they ask: What fundamental principles (laws of physics, basic equations) govern this system? By understanding those, they can derive predictions or engineer solutions. For instance, if an engineer wants to design a more energy-efficient refrigerator, she shouldn’t start by just copying existing fridge designs. A first-principles approach would begin with the laws of thermodynamics – the physics of heat, energy, and entropy – since those laws dictate what is possible for cooling systems . Starting from thermodynamic principles (e.g. how heat flows, the Carnot efficiency limit), the engineer can then determine what must be true for any efficient refrigerator and identify novel ways to achieve cooling that previous designs might have overlooked. In fact, a domain expert might break it down further: a theoretical physicist could dive into the principles behind the Second Law of Thermodynamics to explore new refrigeration cycles that defy conventional expectations . In short, the science approach is to anchor problem-solving in unchanging natural laws – these are the “first principles” for engineers and researchers.
We can also see first principles thinking in how great scientists approach learning and problem-solving. They often derive formulas or solutions from scratch using fundamental knowledge, rather than memorizing answers. Richard Feynman, mentioned earlier, was legendary for re-deriving physics equations from basic principles whenever he needed them, which ensured he truly understood the material. Another example is Albert Einstein. Einstein’s theory of special relativity was born from examining fundamental inconsistencies in physics (like the speed of light being constant) and reasoning from two basic postulates, instead of accepting the established Newtonian analogy of absolute space and time. By trusting first principles (the laws of light and the principle of relativity) over prevailing assumptions, Einstein was able to revolutionize physics. These examples show that in science, first principles reasoning drives progress: researchers strip problems down to core truths and then reconstruct understanding in a way that aligns with those truths, often yielding groundbreaking insights.
Entrepreneurship and Innovation: Elon Musk and Beyond
In the world of entrepreneurship and technology, first principles thinking is a key to disruptive innovation. No one illustrates this better than Elon Musk, who explicitly credits his success in multiple industries to reasoning from first principles. Musk, who has a background in physics, describes first principles as a “physics framework” for solving problems – you “boil things down to the most fundamental truths and reason up from there” rather than copying what’s been done . When Musk started SpaceX in 2002, conventional wisdom said that rockets were extremely expensive and only governments or huge aerospace companies could build them. Instead of reasoning by analogy (i.e. “rockets have always cost millions, so any new rocket will also cost that much”), Musk went back to basic physics and raw materials. He asked himself: “What is a rocket made of?” The answer: aerospace-grade aluminum alloys, titanium, copper, carbon fiber, and other materials . Then he researched the going rate of those raw materials on the commodity market, and found that the materials cost was around 2% of the price of a finished rocket . This was an eye-opening revelation – it meant that if one could buy those materials and assemble a rocket efficiently, the price might be dramatically lower. Musk realized the high cost was not a law of physics but an artifact of how rockets were traditionally built (analogy thinking). In his words, “the only reason [for high rocket cost] is that people are stuck in a mindset that doesn’t hold up to first principles.” Armed with this insight, Musk founded SpaceX to build rockets from scratch, focusing on engineering fundamentals and cost-efficiency from the ground up. The result? Within a few years, SpaceX had slashed the cost of launching a rocket by about a factor of ten while still turning a profit . This incredible innovation – culminating in reusable rockets – was born directly from first principles reasoning about materials and physics.
Musk applied the same thinking at Tesla. A common belief in the early 2000s was that battery packs for electric cars would always be expensive (historically around $600 per kilowatt-hour), making electric vehicles impractical for the mass market. Rather than accepting this, Musk again broke the problem down: What are the fundamental components of a battery? He listed the materials – cobalt, nickel, aluminum, carbon, polymers, and a steel can – and calculated how much those ingredients would cost on the market . It turned out the raw materials for a battery were only about $80 per kWh of storage . In a first-principles view, then, there was no physical reason electric car batteries had to be exorbitant; it was a matter of finding a clever way to combine those materials into a functioning battery at low cost. This insight drove Tesla to innovate in battery design and manufacturing, contributing to dramatic reductions in battery prices over time. As Musk explained, if you simply assumed “that’s just the way it is” because historically batteries were costly, you’d never try – but by questioning the assumption and digging down to materials, you discover the situation “clearly” can be changed . Today, Tesla’s success in electric vehicles and stationary storage is a testament to first principles thinking yielding real-world results.
Musk is not the only entrepreneur who uses first principles reasoning. Other innovators likewise identify core truths in their industry and build products or strategies around those truths. For example, entrepreneur Johannes Gutenberg (inventor of the printing press) can be seen as an early case of first principles innovation. Printing books in the 15th century was slow and costly because it relied on copying by hand or crude woodblock presses. Gutenberg broke the problem down: the essentials of text reproduction were movable type, ink, paper, and applied pressure. He realized that a recent invention, the screw wine-press, could be adapted to apply pressure efficiently on inked type . By recombining elements from different domains (printing and wine-making), Gutenberg created a press that could print pages quickly and uniformly – a world-changing innovation . This happened because he questioned the assumption that one had to stick to existing printing methods and instead thought from the basic requirements of the task.
In modern business, we also see first principles thinking in strategies. The founder of BuzzFeed, Jonah Peretti, identified that the first principle of a successful online media site was not traditional journalistic merit, but wide distribution – getting content that people want to share widely on social media . By focusing on that core insight (what content triggers people to share), BuzzFeed grew explosively using a new model of viral content, rather than imitating the old newspaper or portal website models . Another entrepreneur, Derek Sivers, applied first principles when building his online music store CD Baby. He asked: What does a successful business really need? The answer he chose was simply “happy customers,” and so he ignored many standard trappings of startups (chasing VC funding, flashy offices) and focused on delighting each customer in creative ways . This contrarian approach – stripping a business down to the principle “serve the customer” – enabled Sivers to thrive with a lean operation while others burned through cash on non-essentials . These examples across entrepreneurship show that first principles reasoning can challenge industry norms and yield novel business models or products. By starting with “What are we really trying to achieve, fundamentally?” and “What true constraints do we have (versus assumed constraints)?”, innovators can bypass the status quo and discover more effective solutions.
Design Thinking and Problem Solving: Reframing the Problem
Design thinking and creative problem-solving disciplines have embraced techniques very similar to first principles thinking. Central to design thinking is the idea of questioning the brief – reframing the problem you’re trying to solve by understanding the core needs and assumptions. This often means peeling back why a certain feature is needed or why a process is done a certain way. A well-known method from engineering and product design is the “Five Whys” technique, originally from Toyota’s manufacturing philosophy. By asking “Why?” five times (or as many times as needed) about a problem, you drive toward the root cause or fundamental requirement. Children do this instinctively – they ask “Why? Why? Why?” endlessly – and while it can exasperate adults, it’s essentially first principles analysis in its purest form . Each “why” question forces you to examine the reason behind something, often exposing that many reasons are just assumptions or habit. This method helps designers and problem-solvers to identify which aspects of a situation are truly fixed by nature or physics, and which aspects are merely conventions or legacy from earlier solutions.
Another powerful questioning framework is the Socratic method. By systematically probing the assumptions, evidence, and logic behind a statement, Socratic questioning teases out first principles. In practice, a designer might use Socratic questions like: “Why do we think this feature is necessary? What assumption does it rest on? Is that assumption always true? What if the opposite were true?” Through such questions, one can separate must-haves from nice-to-haves and uncover fresh ways to meet a user’s underlying need . For example, consider early smartphone design. If the problem is defined as “How do we make a better Blackberry phone?”, you might just add a nicer keyboard or a bigger screen (analogy thinking). But a first-principles reframe might ask: “Why do people need a portable computing device? What essentials does a user truly require on the go?” Questions like these led designers to realize a multi-touch screen could replace a physical keyboard entirely, resulting in the paradigm-shifting iPhone. By challenging the assumption that a “phone” must have a physical keypad (because all earlier phones did), designers opened the door to a new form and user experience. This illustrates that in design, as in other fields, re-examining core assumptions can produce innovations that feel obvious in retrospect but were missed by those trapped in analogy.
Modern design thinking frameworks explicitly encourage this kind of reasoning. Teams are urged to empathize with the user’s fundamental needs, define the core problem (often different from the initially stated problem), and ideate without self-imposed constraints. The underlying message is “don’t accept the brief or the existing solutions as gospel – dig down to what’s really needed and build up from there.” This is first principles thinking at work. Whether it’s designing a better city layout, a user interface, or a healthcare process, starting from first principles means focusing on the essential function or goal and exploring all possibilities to achieve it, unconstrained by how it’s been done historically. The result is often more creative, human-centered solutions. As one expert cleverly summarized: “Optimize the function. Ignore the form.” In other words, figure out what you’re really trying to accomplish – the core outcome – and don’t get hung up on the traditional form that outcome has taken in the past. This mindset is what allows designers and innovators to, for example, see an airplane where others only saw a “flying car,” or to add wheels to a suitcase when others only saw “bags.” It’s a mindset of possibility unbound by precedent.
How to Apply First Principles Reasoning (Step-by-Step Guide)
Adopting first principles thinking is a deliberate process. Here is a step-by-step guide to apply first principles reasoning to solve problems or innovate:
- Define the problem and identify your assumptions: Clearly state the problem you want to solve or the goal you want to achieve. Then, list out everything you (and others) are assuming about the problem . These could include beliefs about what solutions are possible, how things “must” be done, or any constraints that you take for granted. At this stage, try to be exhaustive – write down the “obvious” truths you’ve been treating as immovable. For example, you might assume “Growing my business will cost a lot of money” or “This device has to be a certain size because that’s what users expect.” . Bringing these assumptions to light is crucial, because they will soon be put to the test. (As Albert Einstein reputedly said, “If I had an hour to solve a problem, I’d spend 55 minutes thinking about the problem and 5 minutes thinking about solutions,” underscoring the importance of properly understanding and defining the problem .)
- Question every assumption to find the core truths: For each assumption on your list, challenge it. Ask “Why is this true? How do I know this? What if the opposite were true?” Essentially, you want to trim away unwarranted assumptions and see what’s left. Use child-like curiosity and the “Five Whys” approach – keep asking “why?” until you reach a fundamental explanation or you hit a natural law that underpins the issue . Through this process, you may discover that many constraints are self-imposed or based on outdated analogies. Distill the problem down to its irreducible elements. What are the facts or first principles that you absolutely must work with? Musk describes this step as boiling things down to “the fundamental truths” . At the end of this step, you should have a short list of first principle facts or requirements that are definitely true in this situation. Everything else is up for creative reinterpretation. (If you find it challenging to do this alone, Socratic questioning can help: have someone ask you probing questions about why you believe each aspect is necessary . This can expose hidden assumptions and biases.)
- Derive a solution from the fundamental truths: Now, take those basic elements and brainstorm new ways to achieve your goal given those truths. This is the creative part – you’re essentially rebuilding from the ground up. Because you’re no longer constrained by pre-existing models, allow yourself to imagine alternatives freely. One technique is to consider analogies from other fields: since you’re working with fundamentals, you might combine them in ways that are used elsewhere. (Recall the earlier example: motor + skis + tank treads + bike handles were recombined into a snowmobile .) Ask yourself, “Given these raw ingredients and facts, what could I create to solve the problem? Is there a completely different way to arrange these pieces?” It can help to consider the ideal solution first (if cost or technology were no issue) and then see if any fundamental piece truly prevents that, or if there’s a clever way around it. For instance, Musk’s team, after breaking down the cost of batteries to raw materials, asked: what is a clever way to put those materials together into a battery? This led to innovations in battery manufacturing that achieved far cheaper battery packs . The key here is imagination grounded in facts – since you know your first principles are valid, any combination or strategy that respects those principles is fair game. Often, this step reveals solutions that sound unconventional but make logical sense given the fundamentals. Don’t be afraid to think outside the box; in fact, you have deliberately removed the box (the old constraints) in the previous step.
- Prototype, test, and iterate: Reasoning from first principles might give you a brilliant concept, but it still needs to be tested in the real world. The final step is to implement your new solution on a small scale (if possible) and see how it works. Build a prototype or run an experiment to validate that your idea actually holds up and solves the problem. Because your solution is likely novel, expect a period of refinement and continuous improvement. First principles thinking sets a new direction, but practical success may require many iterations to get it right . For example, even after SpaceX had the fundamental idea for a cheap, reusable rocket, it took numerous design adjustments and test launches to iron out the kinks . Use the feedback from testing to improve the solution, but stay true to the first principles you identified – these are your guideposts to ensure you don’t slip back into convenient but false assumptions. Over time, your solution will mature, and you’ll have something truly innovative that stands on solid principles. Throughout this process, maintain a willingness to revisit steps 1–3 if new information arises; sometimes testing reveals that something you thought was a first principle wasn’t absolute after all, and you may need to refine your core assumptions. This iterative loop of learn → rethink fundamentals → improve is how first principles reasoning leads to robust, creative outcomes.
Tip: Adopting first principles thinking can be mentally demanding at first. It requires one to “think hard” and question habits that feel second-nature. Musk has noted that “reasoning by analogy is mentally easier” because it relies on familiar references, whereas first principles thinking “takes a lot more mental energy” . Don’t be discouraged by the effort – start with small problems to build the skill. Practice asking “why” and tracing problems to their roots in everyday situations. Over time, you’ll train yourself to naturally see the fundamental level of issues. The reward is that you’ll gain a reputation for original thinking. While others solve problems by copying existing models, you’ll be the one coming up with ideas that are truly new and effective. In a rapidly changing world, the ability to ground your reasoning in first principles is like having a compass when everyone else is navigating by following old maps.
Conclusion
First principles reasoning is a timeless tool of intellectual exploration and innovation. By insisting on foundational truth and clarity, it allows us to cut through complexity and convention. History’s great minds – from Aristotle questioning the basis of knowledge, to Descartes rebuilding philosophy, to engineers and entrepreneurs reinventing technology – have all relied on this mode of thinking to some extent. In our own lives and work, cultivating a first principles mindset can help us tackle challenges that seem unsolvable and make our thinking more rigorous and creative. It teaches us to be skeptics of “because that’s how it’s always been” and fans of “what if we started from scratch?”. Of course, not every problem requires reinventing the wheel – but when you encounter obstacles or need a quantum leap in understanding, reasoning from first principles is a proven approach to find a way forward. As a final reminder, be wary of ideas you inherit without question: if you catch yourself or your team saying “we can’t do X because nobody does it that way,” that’s a signal to dig down to first principles and see if that’s truly the case . By doing so, you just might discover a solution that breaks the mold and sets a new precedent for others to follow. Reasoning from first principles is both a discipline and an adventure – one that can lead to some of the most profound and game-changing insights across all domains of human endeavor.
Sources: The concepts and examples above were drawn from a variety of sources on first principles thinking, including analyses by Farnam Street , James Clear , and insights from Elon Musk and other innovators . These illustrate how first principles reasoning works in theory and in practice, from ancient philosophy to cutting-edge technology. The step-by-step framework is synthesized from thought leaders who have studied and applied first principles thinking in fields like business and design . By studying these examples and techniques, anyone can begin to incorporate first principles reasoning into their problem-solving toolkit.