Do You Really Know Why You Believe What You Believe?
The Question You Can’t Answer
Ava is in seventh grade. One day at lunch a friend asks, “What’s the capital of Illinois?” Without hesitating, Ava says “Springfield.” Then the friend follows up: “How do you know that?” Ava opens her mouth, then closes it. She can’t remember where she learned it. Was it from a textbook in fourth grade? From a documentary? From a game? She just knows it. But does she really have good reasons if she can’t point to them?
Philosophers have asked this kind of question for centuries. They want to know whether knowing something—or having a belief that’s justified—requires you to be able to reflect and find the reasons inside your own mind. Or can your beliefs be perfectly okay even if you can’t see those reasons?
Can You Always Find Your Reasons Just by Thinking?
In the early twentieth century, the British philosopher H. A. Prichard (1871–1947) proposed a bold idea. He said that when you know something, you either can directly know that you are knowing it—just by reflecting quietly, without doing any extra research. He called this “knowing by reflection.” This is the KK‑thesis: knowing implies knowing that you know.
Prichard’s view is a form of knowledge internalism. Internalists think your knowledge basis—the reasons, experiences, or evidence that support your belief—must be something you can become aware of, at least with some quiet thought. For example, if you know there is a flock of geese in the park because someone just told you, an internalist expects you to be able to reflect and bring that testimony to mind as your reason.
Not all internalists say you have to be aware of your knowledge basis right now. Many hold that you only need to be able to become aware later, just by thinking. That is accessibility internalism. It comes in weaker and stronger versions. Suppose that some item really is an essential part of your knowledge basis. Weak accessibility says you can become aware of what that item is. Strong accessibility says you can become aware that the item actually is your knowledge basis. Both versions focus on your ability to reflect—not on having everything in mind at once.
Justifiers: What Gives a Belief Its Backbone?
Philosophers use the term justifier for whatever makes a belief justified. A justifier could be a past experience (seeing a tree), a memory (recalling a teacher’s words), or a piece of reasoning. When you hold a justified belief, internalists say you must be able to reflect and find at least some essential part of your justifiers.
But we carry around thousands of justified beliefs at once. Right now you probably believe that Abraham Lincoln was the sixteenth U.S. president, that water freezes at 0°C, and that your own name is whatever it is. If you had to call up every single justifier for each one, you would be swamped. That is why internalists usually only require that you can access some essential part—not the whole kit.
Some philosophers go even further. Mentalists, like Earl Conee and Richard Feldman (both late twentieth century), argue that all justifiers are mental states—your own beliefs, experiences, or sensations. According to this view, called mentalism, only what is inside your mind can justify your beliefs. Nothing in the outside world counts as a justifier unless it shows up as something in your mind.
Is Justification a Secret Duty?
There is another way to think about justification—one tied to what you ought to do. Some philosophers say that being justified is a deontological concept: it is about living up to your intellectual duties. When a scientist gathers evidence and follows it honestly, we admire her because she is doing what her evidence demands. If she ignored solid evidence just because she didn’t like where it pointed, we might say her belief was not justified—she failed her epistemic duty.
A famous story helps make this point. Imagine Maud, who believes she has clairvoyant powers, even though her family and friends flood her with scientific evidence that such a power is impossible. One day a belief pops into her head—that the President is in New York City—and she holds onto it simply because she trusts her alleged clairvoyance. It turns out the belief is true, and her clairvoyant process is in fact perfectly reliable. Yet most of us feel that Maud’s belief is not justified. She irresponsibly ignored evidence that she could easily have considered. This suggests that part of what we mean by “justified” is that you haven’t ignored your duties as a thinker.
The Hidden Machinery of Your Mind
Externalists about justification deny that you must be able to access your justifiers. They say your beliefs can be justified even if you couldn’t figure out those reasons through reflection alone. A powerful externalist theory is the reliable process theory, defended by Alvin Goldman (1938–2024). The idea is simple: a belief is justified if it is produced by a reliable belief‑forming process—a mental method that usually yields true beliefs. You do not need to be aware of the process at all.
Think of an avatar in a video game. Inside the game, the character “believes” there is a wall ahead because the code reliably generates that belief. The character cannot inspect the code. The belief is justified by the reliability of the hidden programming, not by the character’s inner awareness. That is externalism in a nutshell.
Externalists often point to a problem for internalists called the Subject’s Perspective Objection (SPO). Consider Norman, a reliable clairvoyant who has absolutely no idea how his power works and no evidence that he has it. When a true belief about the President’s location pops into his head, from Norman’s own perspective it feels exactly like a stray hunch. Many philosophers think Norman’s belief is not justified because he cannot see any reason for it—which sounds like a win for internalism. Externalists, however, reply that this case only shows that a little access is sometimes helpful, not that access is always required.
A deeper challenge is the dilemma of strong access. If internalism demands strong awareness—that you must be able to know that something is a justifier—then you need a justifier for that second‑order belief, and a justifier for that, leading to an endless chain no real person could complete. If internalism settles for weak, non‑conceptual awareness (just a raw feeling with no judgment), then from your own perspective your belief feels exactly like a random hunch—the SPO strikes back. Many philosophers see this dilemma as a serious obstacle for access internalism.
What It Means for You
So why does this dusty argument matter? You have had the experience of confidently knowing a fact—maybe “bats are mammals”—without being able to remember how you learned it. You might worry: Is my belief still okay? An internalist would say you should be able to dig up some justification just by reflecting; if you can’t, perhaps your belief is not truly justified. An externalist would say that as long as your belief was formed by a reliable process—a good teacher, a trustworthy book—your belief is justified even if you can’t retrace the steps.
This connects to everyday disagreements. When you argue with a friend and demand, “How do you know?” the internalist thinks that is a fair request: a justified person should be able to produce some reasons. The externalist replies that sometimes a belief is justified even if the person can’t explain it on the spot—like a skilled chess player who “just knows” the best move. The debate helps us think about what we really owe each other when we share what we believe.
The fight between internalists and externalists is not settled. It forces us to ask: How much of your own mind can you really see? And does it even matter?
Think about it
- Suppose you believe a fact but have completely forgotten where you learned it. Does that make your belief less justified, or is it still perfectly okay?
- If a highly reliable book told you something, and you believed it, would your belief be justified even if you never looked inside the book to check?
- Is it fair to expect your friend to always explain the reasons for every single thing they believe? Why or why not?
