Know What You Don't Know

# Circle of Competence Omaha. 1983. Warren Buffett sits in his office, writing to his shareholders. And he uses a phrase that's going to echo through investment circles for decades: "You don't have to be an expert on every company... or even many. You only have to be able to evaluate companies within your circle of competence." Circle of competence. Three words that sound almost *boring*... until you realize what they actually mean. Which is that most of us are walking around pretending our circle is way bigger than it is. Here's the thing: Buffett didn't invent some new financial instrument. He didn't discover a hidden market inefficiency. He just said, out loud, what nobody wanted to admit. That knowing what you *don't* know... might be more valuable than what you *do* know. That the edge isn't in being smarter than everyone else. It's in being honest about where your knowledge actually stops. His mentor, Benjamin Graham, had laid the groundwork back in 1950 with *The Intelligent Investor*. Graham never used the exact phrase... but the whole book is basically a love letter to limitations. Know your strengths. Know your weaknesses. Don't pretend you're something you're not. Graham had watched the 1929 crash destroy people who thought they understood markets they'd never studied. He lost nearly everything himself. That humility wasn't philosophical. It was scar tissue. Buffett took that idea and gave it a name. A boundary. A shape you could draw. But let's be real. This goes against everything we want to believe about ourselves. Ninety-three percent of American drivers think they're above average. Which is... you know... mathematically hilarious. We are spectacularly bad at assessing our own competence. And that's not just ego talking. Enter David Dunning and Justin Kruger. Two psychologists at Cornell who, in 1999, decided to test something that probably seemed obvious... but nobody had really measured. They gave people tests. Grammar. Logical reasoning. Humor. Then they asked them to guess how well they'd done. The people who bombed? They thought they'd *crushed* it. Bottom quartile performers overestimated their ability by almost fifty percentile points. They weren't just a little off. They were living in an alternate reality. And the people who actually knew their stuff? They *under*estimated. They were so aware of what they didn't know that they assumed everyone else knew it too. Here's what's wild about the original study: Dunning and Kruger tried to *fix* the problem. They took the worst performers and gave them training. Actual instruction on the material. And you know what happened? Their performance improved, yes. But more importantly... their ability to assess themselves improved. They suddenly realized how bad they'd been. Learning made them *less* confident, not more. The path from incompetence to competence passes through a valley of humiliation. This became the Dunning-Kruger effect. And it's basically the scientific version of that moment when you're at a party... and someone who took one economics class starts explaining monetary policy with the confidence of a Federal Reserve chair. The less you know, the more certain you feel. The more you know, the more you see the gaps. Dunning later said something that stayed with me: "The scope of your ignorance is invisible to you." You can't see what you can't see. Your circle of competence has no visible border from the inside. You need external feedback. Reality checks. Failures. Just to know where it ends. So here's the turn. If Buffett's circle of competence is about knowing your boundaries... and Dunning-Kruger is about how bad we are at finding them... then the real question becomes: How do you actually figure out where your circle ends? Buffett's answer was weirdly simple. He just didn't invest in things he didn't understand. Tech boom in the late nineties? Everyone's making money on dot-com stocks? Buffett sat it out. People thought he'd lost his touch. Barron's ran a headline in 1999: "What's Wrong, Warren?" His crime? Not buying into companies with no earnings, no profits... just stories. He said, essentially: "I don't know how to value these companies, so I'm not going to pretend I do." And when the bubble burst in 2000... five trillion dollars in market value evaporated. Pets.com. Webvan. eToys. Gone. Suddenly that looked less like caution and more like wisdom. But here's what people miss: Buffett wasn't right because he predicted the crash. He was right because he knew he *couldn't* predict it. The boundary held. But staying inside your circle isn't the same as never growing it. This is where people get confused. They think the circle is fixed. Like you're born with certain competencies and that's it. The circle can expand. It just expands slowly... through what researchers call deliberate practice. There's this study from 1993 by Anders Ericsson and his colleagues at Florida State. They looked at violinists at a Berlin music academy. By age twenty, the best violinists had put in ten thousand hours of deliberate practice. The good ones? Seventy-five hundred hours. The teachers who never made it as performers? Thirty-five hundred hours. Same school. Same instructors. The difference was focused, uncomfortable practice on specific skills... within a specific domain. And here's what matters for the circle of competence idea: that practice has to be *within a domain*. You can't become an expert in "everything." You become an expert in chess. Or classical guitar. Or evaluating insurance companies. The violinists weren't getting better at "music." They were getting better at *violin*. At shifting positions. At controlling vibrato. At sight-reading Paganini. So the circle can grow... but it grows in specific directions. You don't inflate it like a balloon. You extend it, carefully, into adjacent territory where you can actually build real knowledge. Think about it like mycelium. Those underground fungal networks. A mushroom doesn't just expand in all directions at once. It sends out threads into the soil, following nutrients, connecting to roots, building pathways. It grows where conditions support growth. Your circle of competence is the same. You extend into adjacent areas where your existing knowledge gives you leverage. Buffett knew insurance... so he learned reinsurance. He knew consumer brands... so he learned consumer behavior. Each extension built on what came before. And this connects to something happening in business strategy around the same time Buffett was writing those letters. 1990. Two academics named C.K. Prahalad and Gary Hamel published this idea called core competence theory in Harvard Business Review. They were talking about companies, not individuals... but the logic is the same. A company should focus on what it's uniquely good at—its core competencies—and not try to be everything to everyone. They used Honda as the example. Honda's core competence? Engines. Small, efficient, powerful engines. So they put them in motorcycles. Then cars. Then lawnmowers, generators, outboard motors. Same competence, different applications. They didn't try to make airplanes or ships or refrigerators. They stayed in their circle and extended it systematically. Apple's the modern version. They don't make cars. They make computers and phones and they do it really well. That's their circle. Except... wait. Now they're making cars. Or trying to. For a decade they've had Project Titan, hiring thousands of engineers, and it's been a mess. Layoffs. Leadership changes. Strategy pivots. Maybe because making cars isn't in their circle. It's not adjacent to consumer electronics. It's a different domain with different physics, different regulation, different timescales. You can't ship a software update to fix brake failure. Except now we're in 2025 and things are getting weird. Because AI is doing things that used to require deep expertise. You can ask ChatGPT to write code, analyze data, draft legal documents. So does that expand your circle of competence? Or does it create this *illusion* of competence... where you think you understand something because a machine did it for you? That's an open question right now. There's a 2024 study from MIT that tested this. They gave people access to AI coding assistants and measured performance. Junior developers got better. The AI helped them punch above their weight. But here's the catch: they also became overconfident. They thought they understood the code the AI generated better than they actually did. When asked to explain it or debug it... they struggled. The tool gave them output without understanding. A circle that looked bigger but had no substance. Which is exactly the kind of thing Buffett warned against. If you can't explain why the AI made that choice... if you can't verify the output... if you can't see the errors... you're outside your circle. You're just pressing buttons and hoping. Picture a university lecture hall at Cornell in the late 1990s. David Dunning is explaining his findings to a room full of students. The echo of his voice. The scratch of pens taking notes. He's showing them the data. How the least competent people rated themselves highest. And you can feel it in the room. That uncomfortable recognition. Everyone's wondering: Am I one of those people? Am I overestimating myself right now? That's the emotional beat of this whole concept. It's humbling. And humility isn't sexy. We celebrate confidence. Boldness. People who take big swings. But Buffett became one of the richest people on earth by being ruthlessly honest about what he didn't know. That's not a story we tell very often. We prefer the myth of the genius who sees what others miss. But Buffett's genius was simpler... and harder: he saw what he *couldn't* see. Here's what's counterintuitive: experts are often *less* confident than novices. Not because they know less... but because they know more about what they *don't* know. They've seen enough to understand complexity. A beginner looks at investing and thinks: "Buy low, sell high. How hard can it be?" An expert looks at the same thing and sees a thousand variables. Unknowns. Ways to be wrong. There's a beautiful moment in physics that captures this. In 1900, Lord Kelvin—one of the most respected physicists alive—gave a lecture titled "Nineteenth-Century Clouds over the Dynamical Theory of Heat and Light." He said physics was basically complete. Just two small clouds on the horizon to clear up. Those two clouds? They became quantum mechanics and relativity. They shattered classical physics and rebuilt it from scratch. Kelvin was brilliant. He was also standing at the edge of his circle... and didn't know it. So if you're feeling uncertain about something... that might actually be a sign you're learning. And if you're feeling really confident? That might be the moment to pause. But let's not romanticize staying small. There's a real debate about whether this circle of competence thing can become an excuse. A way to avoid growth. To play it safe. To never take risks. Some critics say Buffett's framework leads to excessive risk aversion. That you miss opportunities if you're too rigid about your boundaries. And they're not entirely wrong. Buffett missed Google. Missed Amazon. Missed the entire tech revolution for decades because it was outside his circle. He's admitted this cost him billions. So the question is: How do you expand your circle without stepping so far outside it that you're just guessing? How do you grow without pretending you already know? The answer seems to be: slowly. Deliberately. With awareness. You don't jump from knowing nothing about biotech to investing millions in pharmaceutical companies. You study. You learn. You build adjacent knowledge. You expand the circle inch by inch... not mile by mile. There's also this idea from education called the zone of proximal development. Soviet psychologist Lev Vygotsky came up with it in the 1930s. It's the sweet spot between what you can do alone... and what's completely beyond you. You want to work right at that edge. Where you're stretching but not breaking. That's where the circle grows. Sports psychology uses something similar. Athletes focus on their strengths rather than trying to be good at everything. A basketball player who's great at three-pointers doesn't spend all their time practicing post moves. They make their strength stronger. Steph Curry takes five hundred three-point shots a day in practice. Not layups. Not free throws. Threes. He knows his game. He lives in his circle and makes it devastating. Back to that office in Omaha. Buffett writing by hand. The scratch of pen on paper. He's not trying to sound profound. He's just describing what he does. Stay inside the circle. Know what you know. Don't pretend. It sounds simple. Because here's what it requires: honesty. Discipline. The ability to say "I don't know" when everyone around you is pretending they do. The ability to pass on opportunities that look good but fall outside your expertise. The ability to be okay with being really good at a few things... instead of mediocre at many. And maybe that's the real gift of the circle of competence. Not that it tells you what to do. But that it gives you permission to *not* do things. To say no. To let opportunities pass. In a world that celebrates the polymath, the generalist, the person who can do everything... this framework says: Actually, focus is power. Boundaries are power. Knowing what you don't know is power. So here's what you can actually do with this. Tomorrow. Or today. Pick one area where you're making decisions. Could be work. Could be personal finance. Could be how you're raising your kids. And ask yourself: Am I inside my circle of competence here... or am I winging it? If you're winging it, that's not automatically bad. But you should *know* you're doing it. You should price that uncertainty into your choices. And if there's something that matters... something where you're consistently operating outside your circle... maybe that's the thing to study. Not everything. *That* thing. Grow the circle there. Deliberately. Over time. Because the goal isn't to know everything. The goal is to know what you know... know what you don't... and be honest about the difference. That's the edge. That's the whole game.