Occam’s Razor

Legend has it that NASA spent a decade and millions of dollars developing a ballpoint pen that would work in zero gravity and function in extreme temperatures. The Soviets used a pencil. The story of the “write stuff” is a myth—pencil tips break and float into equipment or eyes—but the moral holds: simplicity often outperforms complexity.

Occam’s razor is a mental model often summarized as “the simplest answer is usually the correct one.” While that captures the spirit, it oversimplifies a more powerful idea. The principle is named after William of Ockham, a 14th-century friar, philosopher, and theologian known for cutting through tangled arguments, though the model itself was formalized by later thinkers. Occam’s razor is a guiding preference: when multiple hypotheses explain the data equally well, the one that makes the fewest assumptions should be favored. Carl Sagan put it well: “When faced with two hypotheses that explain the data equally well, choose the simpler.” In other words, “when you hear hoofbeats, think horses, not unicorns.”

The value of cutting away needless complexity has roots beyond philosophy; it also aligns with a scientific principle. The second law of thermodynamics leads to the principle of minimal energy—systems naturally tend toward the lowest energy state. In problem-solving, that translates into seeking the solution with the least “expense” of assumptions, components, or effort.

Albert Einstein famously said everything should be made “as simple and as few as possible,” and the razor appears across many domains. Scientists use it to decide whether a hypothesis is worth pursuing: a theory that is easy to prove or falsify is more fruitful than a convoluted one. In medicine, doctors apply the razor every time they see a patient, looking for the fewest causes that can explain a set of symptoms. Arthur Conan Doyle’s Sherlock Holmes embodied the same instinct, asserting that once you eliminate the impossible, whatever remains—no matter how improbable—must be the truth.

The rocket scientist David Murray echoes this elegantly: the most elegant solutions “use the least number of components to solve the greatest number of problems.” Newton’s third law, “for every action, there is an equal and opposite reaction,” is a simple statement that explained rocketry centuries before it was possible. When we truly understand something, complexity tends to dissolve; as Peter Attia notes, the more we know, the less complicated a subject becomes. Words like “multifactorial” and “complex” often signal that we haven’t yet found the simple core.

Simplicity also reduces points of failure. Complicated things break more easily. Apollo 8’s safety manager observed that with 5.6 million parts, even 99.9% reliability would still yield 5,600 defects. In business, every decision that complicates a system multiplies the ways it can go wrong. SpaceX builds Falcon 9 with identical engines and a common diameter across stages, using the same aluminum-lithium alloy. This simplicity lowers costs and improves reliability—fewer components mean fewer things to buy, maintain, and fix. The Russian Soyuz launcher, simpler than the Space Shuttle, is often considered more reliable. As astronaut Paolo Nespoli put it, “Sometimes when you do less, less is better.”

Natalya Bailey, founder of Accion, applies this thinking to spacecraft propulsion. Her electric engines are the size of a deck of cards, using ions instead of hot gases. This approach is slower but ten to a hundred times more energy-efficient, safer, and radically simpler than chemical alternatives. Her philosophy mirrors that of chef Grant Achatz, who shifted from constantly asking “What else can we add?” to “What can we take away?”—a process Michelangelo called arriving at the end by taking away what is superfluous.

However, the razor cuts both ways. Simplicity isn’t the same as ease—distilling complexity takes tremendous effort, as the famous quote “If I had more time, I would have written a shorter letter” suggests. And Occam’s razor is not an excuse to ignore nuance. As H. L. Mencken cautioned, a simple solution can be “neat, plausible, and wrong.” In some cases, the complex explanation is indeed the correct one. The mathematician Alfred North Whitehead advised, “Seek simplicity and distrust it.” Use the razor as a starting point, not a final verdict. Stay open to new facts, and remember: what you need is rarely hidden in someone else’s overly complicated playbook. Often the most powerful thing you can do is cut back to the essential, letting the simple reveal itself.