Michael: You probably think you know what ‘knowledge’ is. But what if I told you that for over 2,000 years, philosophy’s best definition was broken, and a single, three-page paper in 1963 proved it? It turns out, being right isn't enough. Kevin: Whoa, hold on. A three-page paper broke a 2,000-year-old idea? That sounds like the philosophical equivalent of a kid with a paperclip taking down a bank vault. What are you talking about? Michael: It's the central puzzle we're exploring today, drawn from Jennifer Nagel's fantastic book, Knowledge: A Very Short Introduction. Kevin: A 'very short' introduction to a 2,000-year-old problem? That sounds ambitious. Michael: It is, but Nagel, who's a Canadian philosopher, is brilliant at this. She's known for making these huge, complex ideas incredibly clear and accessible, which is why the book is so highly-rated by readers. She doesn't just give you answers; she guides you through the questions, which is exactly what we'll do today. Kevin: I like that. Less of a lecture, more of a detective story. Michael: Exactly. And to see how it all fell apart, we first have to build the thing that broke. So, what was this classic, seemingly perfect definition of knowledge?

Michael: Let me ask you, Kevin. If you say you know something, not just think it or hope it, what does that imply? What ingredients do you need? Kevin: Okay, well, first, I have to actually believe it. I can't know something I don't believe. And second, it has to be true. I can't 'know' that the sky is green. Michael: Perfect. That's Belief and Truth. Two essential pillars. Philosophers have long agreed on those. But there's a third, crucial ingredient. Imagine a coin is tossed and put in a sealed, opaque box. It's either heads or tails—that's a fact, a truth. But does anyone know what it is? Kevin: No, of course not. It's hidden. You need access to the fact. Michael: Exactly. Knowledge requires a knower. But let's add another layer. What if you just take a wild guess? You say, "I believe it's heads!" and you happen to be right. Do you know it's heads? Kevin: No, that's just a lucky guess. I had no reason to think that. Ah, I see. You need a good reason for your belief. A justification. Michael: Precisely. And that's the classic, three-part recipe for knowledge that stood for centuries: Justified True Belief. Or JTB, for short. To know something, you must (1) believe it, (2) it must be true, and (3) you must be justified in believing it. Kevin: That makes a lot of sense. It feels complete. For example, I know I'm holding a coffee mug. I believe it, it's true, and my justification is that I can see it, feel it, and taste the coffee. It covers all the bases. Michael: It seems to. And it helps us spot the difference between knowledge and other states. Take the story Nagel tells of a father whose daughter is accused of a crime. He is absolutely convinced she is innocent. Let's say, for the sake of argument, she is truly innocent. So his belief is true. Kevin: Okay, so he has a true belief. Michael: But his justification is purely emotional. He says, "I just know my daughter, she could never do that!" He refuses to look at any of the evidence, the police reports, the witness statements. Is his justification good enough for him to know she's innocent? Kevin: I'd say no. His belief is based on love and denial, not evidence. He's avoiding the facts, not engaging with them. So even though he's right, he doesn't really know. He just happens to believe the right thing. Michael: Exactly. His justification is flawed. So this JTB model seems to work perfectly. It weeds out lucky guesses and blind faith. It feels robust, logical, and complete. Kevin: Yeah, it seems rock-solid. I can't see a flaw. What could possibly be wrong with that? Michael: That's what everyone thought. For two millennia, from Plato onwards, this was the gold standard. It was the bedrock of epistemology. And then, it all came crashing down.

Kevin: Okay, you've built this up. I'm on the edge of my seat. How does a rock-solid, 2,000-year-old definition just... break? Michael: It breaks with a story. In 1963, a philosopher named Edmund Gettier, in that tiny three-page paper I mentioned, presented a couple of thought experiments. They've become known as "Gettier cases," and they're designed to show you can have a perfectly Justified True Belief and still not have knowledge. The most famous version, which Nagel discusses, is the story of the broken clock. Kevin: I'm ready. Hit me with it. Michael: Alright. Imagine a man named Smith. He's walking through a deserted train station on a Sunday afternoon and he's lost track of time. He needs to know the time, so he looks up at the big, official-looking station clock on the wall. The clock reads 1:17. Kevin: Okay, seems like a reliable source. Michael: It does. So, Smith forms the belief, "The time is 1:17." And he's perfectly justified. Looking at a large public clock is a standard, reasonable way to find out the time. Now, here's the twist. Unbeknownst to Smith, that clock is broken. It stopped working two days ago, and its hands are frozen at 1:17. Kevin: Ah, so his belief is false. He doesn't know the time. Michael: But here's the second, crucial twist. By sheer, one-in-a-million cosmic luck, Smith happens to glance at that broken clock at the exact moment it actually is 1:17 in the afternoon. Kevin: Wait. What? No. Come on. Michael: Yes. So let's run it through our checklist. One: Does Smith believe it's 1:17? Kevin: Yes, he does. Michael: Two: Is his belief true? Kevin: Yes, by a crazy coincidence, it is. Michael: Three: Is he justified in believing it? Kevin: Yes! Looking at a station clock is a perfectly good justification. He has no reason to think it's broken. So... he has a Justified True Belief. Michael: He has a perfect Justified True Belief. But Kevin... does he know what time it is? Kevin: Oh, man. No. Absolutely not. He has no idea what time it is. He just got incredibly, absurdly lucky. His justification—"I saw it on the clock"—is based on a false premise, that the clock is working. But the final belief is true anyway. That's a total mind-bender. Michael: That's the Gettier bomb. That's the glitch in the matrix of epistemology. It's a case where all the conditions for knowledge are met, but our intuition screams that it isn't knowledge. It's just a lucky accident. And once you see it, you can't unsee it. These cases show that justification and truth can be disconnected. You can be right for all the wrong reasons. Kevin: That's wild. It's like correctly guessing a password because you thought it was your birthday, but it was actually a random string of numbers that just happened to match your birthday. You were right, but you didn't know the password. So what do philosophers do after their 2,000-year-old definition gets torpedoed like that? How do you even begin to fix that?

Michael: That's the billion-dollar question in philosophy, and it split the field into two major camps. Everyone agreed that the Justified True Belief formula was missing something. The debate was about what that missing ingredient was. The two big answers are known as Internalism and Externalism. Kevin: Okay, Internalism and Externalism. Layman's terms, please. Michael: Of course. Let's start with Internalism. The internalists looked at the broken clock and said, "The problem is inside Smith's head. His justification was defective, even if he didn't know it." His reasoning chain included a hidden false belief: namely, "that clock is working correctly." Kevin: Right, which it wasn't. Michael: So, for an internalist, for a belief to count as knowledge, your justification has to be internally sound. You have to be aware of your reasons, and those reasons can't be built on a lie or a mistake. Knowledge is about what's accessible to you, from your first-person perspective. You should be able to reflect and see for yourself that your grounds are good. Kevin: That sounds reasonable. It's about mental hygiene. Don't base your knowledge on bad assumptions. So what's the other side? Externalism? Michael: The externalists took a completely different path. They said the problem isn't what's in Smith's head, it's his connection to the world outside his head. The issue wasn't his reasoning, but the process he used. Kevin: What do you mean by process? Michael: They argue that for a belief to be knowledge, it has to be formed by a reliable process. A working clock is a reliable process for telling time. A broken clock is an unreliable process. Smith used an unreliable process, so even though he got lucky, he can't have knowledge. Kevin: Huh. So it's not about what Smith is thinking, but about the tool he's using. Michael: Exactly. Nagel gives another great example: Fake Barn County. Imagine you're driving through a county where, for some weird reason, the locals have put up dozens of incredibly realistic barn facades. They're just fronts, with nothing behind them. But, hidden among them is one single, real barn. Kevin: Okay, I'm with you. Michael: You drive by, point to the one real barn, and say, "Hey, look, a barn." Your belief is true. It's justified by your vision. But do you know it's a barn? Kevin: No, because I could have just as easily pointed to a fake one. My barn-spotting ability is totally unreliable in that specific environment. I just got lucky again. Michael: And that's the externalist argument in a nutshell. Knowledge depends on an external, reliable connection between your belief and the truth. It doesn't matter if you can internally justify it; what matters is whether the process that produced your belief is one that generally gets things right. Kevin: That’s a fascinating split. So, Internalism is like a detective who says, "I know he's guilty because I've reviewed all the evidence in my head and my logic is sound." But Externalism is like saying, "I know he's guilty because the DNA evidence—an external, physical thing—provides a reliable link to him, even if I don't fully understand the science behind it." Michael: That is a perfect analogy. It's a debate about where the magic of knowledge happens: inside the mind, with our reasons and reflections, or in the connection between the mind and the world.

Kevin: So where does this leave us? After the JTB definition was broken and philosophers split into these two camps, is there an answer? Do we know what knowledge is now? Michael: The fascinating thing, and Nagel's book makes this wonderfully clear, is that the debate is still very much alive. There's no single, universally accepted "fix" for the Gettier problem. Both Internalism and Externalism have their own strengths and their own tricky counter-examples. Kevin: So the whole field is still kind of up in the air? Michael: In a way, yes. But the quest itself has taught us something profound. The real takeaway isn't a neat new definition. It's the realization that knowledge is so much more than just being right. It's about the quality of the connection between our minds and reality. It's not a static possession; it's a relationship. Kevin: I like that. The quality of the connection. And that feels more relevant today than ever. Michael: Absolutely. Think about the internet, social media, AI-generated content. We are living in Fake Barn County. We are constantly looking at things that look like knowledge—a well-designed website, a confident-sounding influencer, a viral tweet. They look like working clocks. Kevin: But they could be broken. They could be accidentally right, or intentionally misleading. We're all facing Gettier problems every single day. Michael: We are. And that's why this philosophical journey isn't just an academic exercise. The struggle to tell the difference between a lucky guess and genuine knowledge, between a reliable process and a broken one, has become a fundamental survival skill for navigating the modern world. Kevin: Wow. So epistemology isn't just for the ivory tower; it's for anyone with a smartphone. Michael: It is. And it leaves you with a really powerful, maybe even humbling, question to ask yourself. Kevin: What's that? Michael: What's one thing you think you know for sure, and how could you prove to yourself that your belief isn't just a lucky guess from a broken clock? Kevin: That is a great question. And a tough one. We'd love to hear what our listeners think. Find us on our socials and share your 'unbreakable' piece of knowledge, and how you know it's not just luck. Michael: This is Aibrary, signing off.