Photo by Raymond Depardon/Magnum


How do you know?

Correct information doesn’t always come with its own bright halo of truth. What makes something worth believing?

by Nate Sheff + BIO

Photo by Raymond Depardon/Magnum

You can’t be wrong on purpose. To see this, try one of my favourite philosophical parlour tricks. Right now, believe something you think is false: that the Sun is just a big lightbulb, for instance. Don’t imagine you believe it – really believe it. Become so confident in it that you’d bet good money that it’s true. When I try this, I feel a funny cognitive block, as if there’s a built-in aversion to believing on command, especially anything I already think is wrong. Unfortunately, this doesn’t mean it’s easy to believe only truths. If learning and thinking were as easy as deciding to let nothing but the facts in, we would never make mistakes. And yet we stumble into falsehood all the time. We can all think of times we were convinced of something that turned out to be wrong, and we all have our favourite perceptual illusions, ambiguous images and pictures of impossible scenes, which drive it home that things aren’t always how they seem.

With such a track record, it makes sense to reflect on why our thinking sometimes goes awry, and why it sometimes goes right. Epistemology, the philosophical study of knowledge, belief and evidence, starts here, with our fallibility. And from this beginning, there are many paths for epistemology to take, and many sorts of questions to set us down these trails.

For instance, we could continue by asking about the nature of thinking itself. Does thinking amount to nothing more than forming and reforming beliefs? Or is it something else entirely? Another option is to ask what counts as ‘success’ or ‘correctness’ in believing. This second path concerns what epistemologists call ‘justification’. Since true thoughts don’t come with a special glow announcing themselves as true, we can’t use truth as a marker for well-formed, worthwhile beliefs. Rather, we might look for something else to sort the good beliefs and opinions from the bad – something that justifies some beliefs rather than others, and that explains why some are credible and some aren’t.

Indeed, this is the big question for many epistemologists: what justification and credibility actually are. But, along the way, the path narrows, and a new question arises over the role justification plays in finding out things. While a just-the-facts filter can’t solve the problem of avoiding falsehood and getting the truth, does the credibility of a thought need to make itself obvious to you in a way that truth can’t? Or is it enough for your opinion to be credible, full stop? These questions lead to the forbiddingly named internalism/externalism debate in epistemology, but don’t let the -isms scare you off. As we’ll see, academic questions about justification lead to much deeper questions about the subject matter of epistemology itself.

To get a sense for what justification is, consider this analogy. I own a miniature American football helmet signed by the quarterback Brett Favre in the first year he took the Green Bay Packers to the Super Bowl and became MVP (a Most Valuable Player in the US National Football League). (In fact, I personally handed him the helmet to get it autographed.) If I wanted to sell you this piece of sports memorabilia, you would understandably want assurance that the autograph isn’t a forgery, since mini helmets, Sharpies and pictures of Favre’s autograph aren’t hard to come by, and you can’t tell a fake from the real thing yourself. (Genuine autographs don’t come with a special glow, either.) So, a certificate of authenticity from an expert appraiser, someone who can inspect the signature and determine whether, in their opinion, the autograph came from Favre’s own hand, might lend credibility to the claim that Favre autographed the helmet. Once the appraiser certifies the autograph as legitimate, you can rest assured and justifiably purchase the helmet. We could even go a step further and say that, if someone bought the helmet without a certificate, they’d be making a rash decision. (You might wonder whether spending money on sports memorabilia is a rash decision in the first place, but we’ll have to bracket those concerns.)

When we’re tracking something important, we often rely on something else to clue us in to its presence or absence – something like a certificate of authenticity – and the same applies when it comes to our beliefs, thoughts and opinions. To live a human life is to swim in an ocean of information fed by all sorts of channels: our senses, our memories, our social networks. But, just as the squiggles on the plastic football helmet don’t announce themselves as a real autograph to the untrained eye, information doesn’t always come with a bright halo of truth. What makes something worth believing – what makes a belief credible or justified – will have to be something else. But if beliefs require their own ‘certificates of authenticity’, what should those certificates be? That is, how does justification work?

Imagine you’re interested in buying the helmet. If an expert examines it and issues a real certificate of authenticity, and you buy it, you’re buying a certifiably genuine autograph. But in order for you to buy responsibly, in order for the purchase to be justified, how does that certificate of authenticity have to factor in to your decision?

Once the certifying takes place, the table is set for you to buy responsibly

Here’s one school of thought: you can’t buy it responsibly unless you are aware of the certificate of authenticity first. This raises a host of questions. Aware how, and of what? And who certifies the certifiers? Aren’t certificates as vulnerable to forgery as autographs? These are all fair concerns, but the basic underlying appeal of this idea seems clear enough. If you can’t tell faked squiggles from Favre’s squiggles, it’s natural to want a proxy that you can appreciate for yourself. After all, didn’t we want a clearer mark of credibility precisely because the autograph’s authenticity wasn’t obvious to us? What would be the point of the certificate if you couldn’t hold it up and say: ‘Here’s how I know this is the real deal’?

Here’s an alternative school of thought: you don’t have to be aware of the certificate at all to be in the clear for buying the helmet. While you could take a peek at the certificate, you don’t have to, in order for it to do its job. The certificate stands as the record of the fact that an expert found the autograph authentic, and so long as that record of a reliable judge’s findings exists, you can buy the helmet without worry. Once the certifying takes place, the table is set for you to buy responsibly. Isn’t that the certifying expert’s job, after all?

These schools of thought disagree over how certificates of authenticity actually factor into your decision. Since the first school suggests that certificates have to be internal to your perspective as a buyer, we can call it ‘internalist’. The second school says the certificates just have to be produced in the appropriate way for the merchandise, so we can call it ‘externalist’. The buyer doesn’t really have to consult or inspect them.

This distinction between schools resembles the actual debate among epistemologists about the nature of justification. There is the larger question of what justifies our beliefs, and there is the narrower question about how justification factors into the life of a thinking, enquiring person. For internalists in epistemology, my belief cannot be justified unless its justifier can somehow be appreciated by me. Externalists deny this; they say I can have a justified belief even if I can’t check whatever makes it credible.

Is this an academic debate? Absolutely, but I don’t think it’s merely academic. True, you’re unlikely to learn about internalism and externalism unless you’re taking upper-level philosophy courses. Nevertheless, what’s up for grabs are rival conceptions of ourselves as knowers and enquirers, and which conception will take precedence in the theory of knowledge. When we ask the hard questions about our fallible intellects, where should we start? What’s our foundational picture?

For a very long time, most philosophers took internalism for granted as good common sense. If you know something, or have good reason to believe it, then you can justify yourself with a reason you can cite. Take Socrates. His shtick consisted in asking the local experts pointed questions until it became clear that the experts didn’t actually know what they were talking about. For instance, in Plato’s Euthyphro dialogue, Socrates runs into the local priest and expert on the gods, the self-same Euthyphro, who plans to do something unholy by the local standards – to press charges against his own father. Socrates asks how he, a man wise in the ways of the gods, could do something the gods would obviously condemn?

Euthyphro answers that, in fact, his plan passes the gods’ standards. This raises only more questions for Socrates, who presses on and asks Euthyphro to clarify what he means by holiness. If Euthyphro’s plan is so holy, surely he could explain his reasoning and spell out the nature of holiness? Under questioning, though, Euthyphro reasons himself into a corner, unable to give a clear account of holiness. The dialogue ends there, with the premier theologian of Athens excusing himself with a version of ‘I’m actually late for a thing.’

Athens respected Euthyphro for his wisdom in the ways of the gods, but he couldn’t answer some elementary questions about his area of expertise. His ‘knowledge’ seems awfully deficient. Watching Socrates, we get the impression that, if you really know something, then you must be able to give an account. Like in mathematics class, you must be able to show your work. In theory, your account should be the certificate of authenticity that can justify a belief, and this should satisfy internalists, since you’ve produced your account from your thoughts ‘from the inside’. This also makes it suitable for answering the sorts of challenges Socrates would raise.

While Socratic accounts look appropriate in some areas (in geometry, for example, with its explicit step-by-step proofs), we don’t always expect or demand them elsewhere. Many trivia geeks can’t tell you how they know every answer they give – it just pops into their head. Their responses seem better than lucky guesses, but they fall far short of the Socratic ideal of reason-giving.

What good is a certificate of authenticity that can’t be shown?

The same goes for other common sources of justification, like other peoples’ testimony or our own senses. Even so, these sources seem to satisfy the basic internalist idea that justification has to be inside our experience. One view says that having experiences of a certain kind gives your belief a weaker but substantive enough kind of justification. Let’s say I have a sensory experience: I seem to hear the clicking sound that my dog’s nails make on the floor when she walks. This experience leads me to believe that my dog is walking behind me. The auditory experience justifies my belief. It doesn’t prove that my dog is nearby (she might not even be there), but it’s enough to put me in the clear to believe she is.

Like the Socratic view, this view captures the internalist idea by putting everything you need for justification inside your perspective, as available to your reasoning as anything could be. I have a justified belief about where my dog is because I had an experience reminiscent of the sounds of her feet. And the experiences themselves need no justification, since they are, as the philosopher Roderick Chisholm put it in 1966, self-presenting. They make themselves known. And how could they not? What could be more luminous and manifest than conscious experience?

Well, opinions differ. Wilfrid Sellars articulated a lasting difficulty for the self-presentation idea: raw experience isn’t fit to justify. It’s simply the wrong tool for the job. If Euthyphro had answered Socrates’ questioning with a pitch-perfect imitation of a barn swallow, the philosopher might be impressed, but would rightly think that his question had not only been answered inadequately, but hadn’t received the right sort of response at all. Likewise, if you ask me: ‘What reason do you have to think your dog is nearby?’ what good is it to indicate my unrepeatable, inarticulate inner episodes? What good is a certificate of authenticity that can’t be shown? I couldn’t even cite my experience to myself, because, as soon I have the experience, it’s gone.

Every internalist view, even weaker varieties, says that justification has to be accessible from your perspective. Justification always comes from inside. But what is this accessibility? It’s usually imagined as something you could have from the armchair, reflecting on your thoughts, so if you’re justified in believing anything, you can find that justification here and now by looking within. Reflection becomes the means of justifying your beliefs, and that places a huge burden on the shoulders of reflection.

It also means that anyone not sufficiently reflective can’t have justified beliefs. We often talk about what very young children know, even before they learn to talk, and we say that our fellow creatures know things too. I might tell you about an eastern phoebe that knows and remembers where her nest is, but can’t tell that one of her nestlings is a cowbird. While some philosophers happily write off these examples as metaphorical, others find the continuities between mature adult humans and other animals – human or otherwise – too striking to ignore. We all face the same basic problem, after all. We all have to make our way through a changing environment that doesn’t cooperate with us.

To understand our epistemic situation, then, we might look for an alternative to internalism. Internalism’s focus on armchair reflection intellectualises justification. This might seem like a funny complaint. It brings to mind what the philosopher Sidney Morgenbesser reportedly said to the behaviourist B F Skinner: ‘Are you telling me it’s wrong to anthropomorphise people?’ The air of paradox lifts when we remember some of the examples that seem problematic from an internalist point of view. Internalism captures the hard rigour of philosophy and science, where proof and argument are the coin of the realm, but when we start taking the credibility of the beliefs of children and nonhuman animals seriously, it comes up short. They typically do not or cannot reflect, so internalism would have us deny that they can have justified beliefs. The externalist says: ‘So much the worse for internalism.’

Externalism came to prominence in epistemology as reliabilism, which holds that beliefs are justified when produced by a reliable process. The appeal of this view is hard to miss. As we’ve already noted, we rely on a diverse array of information channels – perception, memory and so on – and we rely on those particular ones because they get the right answer often enough. Sure, we occasionally rely on them and make mistakes (I once showed up an hour and a half late to a graduate seminar thinking I was arriving early), but the processes themselves succeed enough of the time that, even when they give you a false belief, those beliefs are still justified. A reliable cognitive process is like a good meteorologist. You can take them at their word even when they have some mistakes in their track record.

And, also like a good meteorologist, the inner workings of a reliable cognitive process do not have to be transparent to you in order to deliver the goods. You can form justified beliefs based on what you see while having no insight into how vision works, or even into the overall reliability of your visual system. For reliabilism, justification flows from the reliability of the process, not its accessibility to consciousness. Hence, reliabilism is an externalist theory, not internalist.

Without the burden of accessibility, externalism can account for the credibility of non-reflective thinkers, such as birds, dogs and toddlers. Frank Ramsey once compared beliefs to maps, so if we model thinking on the production of and navigation by inner maps, it makes sense why we would bring our fellow creatures into the fold. Every thinking thing needs to find its way through environments where the locations of food, friends and enemies can change. So when we’re thinking about credibility and justification for the beliefs of such creatures, we’re interested in what it takes for those creatures to succeed. They need senses that put them in contact with the world. They need reliable processes to lean on.

An internalist might complain: ‘But what about the Socratic practice of giving and asking for reasons?’ Reliabilists – and other kinds of externalists, for that matter – have responded by simply externalising rational reflection. My beliefs about my beliefs come from yet another reliable process: introspection. The mature human’s ability to rationalise is awe-inspiring and entirely appropriate for social creatures who have to juggle competing priorities and egos. But that’s no reason to follow the internalist in propping it up as the source of justification, or as our only means of justifying.

What about when I’m dreaming, or stuck in the Matrix?

Another internalist argument has given externalists more trouble. Let’s go back to our autograph story. In one version of the story, you decide to buy the helmet on the basis of the certificate of authenticity, and everything works out, leaving you the proud owner of a real Favre autograph. But imagine another version with an unhappier ending: the autograph is in fact a forgery so convincing that an appraiser issues a certificate of authenticity for it, and, on the basis of the certificate, you buy the helmet. In the first story, you use the certificate to make a decision, and it gets you what you wanted. In the unhappy version, you use the certificate to make a decision, exactly as before, but it goes wrong due to no fault of your own.

Internalists say that, despite the different endings, we can see a common thread running through both versions of the story. In both cases, you reasoned and decided on the same grounds. As far as you can tell, everything is the same ‘from the inside’ in both versions. The fact that the autograph is faked in the unhappy ending makes no difference to the responsibility of your purchase, since you based your decision on a credible source. If you made the right call in the happy case, then you made the right call in the unhappy case.

We can get the same result with belief. Think about the weather where you are as you read this. How is it? For me, it’s very muggy and overcast. Let’s assume I’m right; that’s the good case. But in the bad case, though everything seems exactly the same as in the good case – it feels humid and looks cloudy – I’m actually dreaming, or stuck in a simulation without my knowledge, or am otherwise tricked, so my beliefs about almost everything, including the weather, are wrong.

Like the happy and unhappy ending for the autograph story, the outcomes of my believing – truth in the good case, error in the bad – don’t really seem relevant to whether I formed my belief in the right sort of way. Everything I have to go on in the good case is there in the bad, and vice versa. The external outcomes of the beliefs are different, obviously, but not the justification.

Externalists have struggled to explain why my beliefs in the good and bad cases seem to be on equal footing. The reliabilist can point to my senses’ reliability to explain my justification in the good case, but what about when I’m dreaming, or stuck in the Matrix? My belief-forming processes won’t be reliable in the bad cases, so I won’t have justified beliefs in them. That cuts against the impression we get from considering these stories. You can make the right call and lose, even in cases of persistent deception.

It seemed like we started with a simple question: whatever justification turns out to be, is it internal or external? We’ve seen that it isn’t so easy. While this appears to be a dispute over a single claim, it’s really a clash between distinct research programmes. To one party of the dispute, when we talk about the justification of a belief, we’re talking about the belief of a reflective, autonomous being, someone we can hold to account, someone responsible to others. Believers can (and must) explain themselves with good reasons.

But the other party doesn’t just disagree with this last point. They disagree about the whole picture of cognition as reflective accounting. Thinking isn’t just for theorising, but for doing and living. To them, we have to centre cognition’s role in animal life in our understanding of credibility. Giving and asking for reasons will come later on, derivative of the more fundamental concerns for creatures of flesh and blood.

Knowers are believers – they react to a prepackaged world by forming sentence-sized opinions

These are incompatible visions of what knowers are. When we frame questions about our fallibility as knowers, we have to ask: ‘Fallibility at what, exactly?’ But the internalism/externalism debate, as it typically plays out, starts downstream of this, as if we already have a satisfactory account of what we’re doing when we enquire: ‘Should we assume this?’

Consider the mind-body problem after René Descartes. In response to Descartes’ conclusion that the mind is an immaterial thing, a materialist might say: ‘No, the mind is the brain! It’s a material thing.’ But wait – by identifying the mind with matter, we’ve inadvertently endorsed a central Cartesian idea: minds belong in the general category of things or stuff. Minds might not be like that at all, though. If we take up ‘the mind-body problem’ as a choice between immaterial substances or material substances, we can miss a third alternative, that ‘the mind’ might be more like a collection of abilities instead of an object. It might be a kind of activity rather than another body part.

In the same way, the internalism/externalism debate might mask deeper issues and promising alternatives. It’s not that ‘Is justification internal?’ is a wrongheaded or malformed question. Rather, it limits our options at a point where the logical space of possibilities should be wide open. After all, what is a knower, according to both internalists and externalists? Knowers are believers – they react to a prepackaged world by forming sentence-sized opinions. But this claim is not a given, no more than is the idea that the mind is a substance.

Let’s retrace our steps. We’ve learned something from asking about justification and whether it’s internal. We’ve seen how different conceptions of justification can embody different theories of what knowers are. We have an opportunity to take the path we noted at the beginning, to explore a more basic question. Reflecting on our track records, our successes and failures, we can ask: ‘What is enquiry? What are we doing when we try to know?’