Epistemology: Internalism vs. Externalism
You Might Know Things You Can't Explain — And That's Not a Flaw
The most important question in epistemology isn't 'what do you know?' — it's 'what makes your belief count as knowledge in the first place?'
The Idea
For centuries, philosophers treated knowledge as something that had to be fully accountable to the knower. If you knew something, you should be able to reach inside your own mind, examine your reasons, and justify the belief from the inside. This view — called internalism — holds that what makes a belief legitimate is something you have direct, conscious access to. Your evidence, your reasoning, your introspective sense that everything checks out. Externalism turns this on its head. It says the conditions that make a belief count as knowledge don't have to be things you're aware of at all. What matters is whether your belief was produced by a reliable process — whether your cognitive machinery, so to speak, is well-connected to the truth. If your visual system is functioning normally, the lighting is good, and you see a bird on the branch, you know there's a bird on the branch — even if you couldn't articulate the optics of colour perception or explain why your eyes are trustworthy. The philosopher Alvin Goldman gave this view its most influential shape in the 1970s, calling it 'reliabilism.' The radical implication is that knowledge doesn't require self-transparency. A child can know their name. A patient with certain memory conditions can know how to ride a bicycle. An expert can know something is wrong before they can say why. This isn't just an academic puzzle. It's a question about whether your mind needs to be its own auditor — and whether that's even possible.
In the World
In 1975, a neuropsychologist named Lawrence Weiskrantz was working with a patient referred to as D.B., who had lost a significant portion of his primary visual cortex following surgery. D.B. was clinically blind in part of his visual field — he reported seeing nothing there. But when Weiskrantz asked him to guess where a light was being flashed in that blind region, D.B. pointed to the correct location at rates far above chance. When told he was right, D.B. was genuinely astonished. He had no experience of seeing. He had no internal access to any evidence. He couldn't justify the belief. And yet, something in him was tracking the truth reliably. Weiskrantz called this 'blindsight,' and it became one of the most discussed phenomena in both neuroscience and philosophy of mind. For externalists, it's close to a perfect demonstration of their view: D.B.'s belief-forming process was reliable even though it was entirely opaque to him. If knowledge required internal justification, D.B. couldn't know anything about what was in his blind field. But that feels like the wrong answer. His case quietly dismantles the assumption that the knowing self is always the one in the room — that consciousness is the site where knowledge lives. Sometimes the machinery runs deeper than awareness, and runs true.
Why It Matters
This debate has a surprisingly personal dimension. Most of us carry an internalist assumption about our own minds — that our beliefs are only trustworthy if we can consciously examine and justify them. This can tip into a kind of epistemic anxiety: the feeling that you don't really know something unless you can fully account for how you got there. But externalism offers a quieter kind of confidence. Your intuition that something is wrong in a relationship, that a decision doesn't sit right, that a person is being dishonest — these might be the outputs of genuinely reliable processes built from years of experience, even when you can't articulate the reasoning. That doesn't mean gut feelings are always right. Reliability is the bar, and some of our instincts are badly calibrated. But it does mean that the inability to explain yourself isn't automatically a disqualification. There's also something useful here for how you hold disagreement. If knowledge can be external to conscious justification, then someone who believes differently from you might not simply be reasoning badly — they might be tracking something you're not. Intellectual humility isn't just a virtue; on the externalist view, it's epistemically warranted.
A Question to Ponder
Is there something you feel certain about but couldn't fully justify — and do you trust it more or less because you can't explain it?
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