Some people think that knowledge is something in the head. I have a belief, and it has appropriate connections to other ideas and beliefs, all in my head. These connections ensure that my belief has good grounding or justification: I have reasons for my belief. And if this particular belief maps onto some structure in the world in the right way, in such a way that we might say my belief is “true”, then I have knowledge. But whatever is “out there” in the world is not my knowledge; it is only a fact or state of affairs that renders my belief true. It’s what is in my head that is my knowledge.

I’m not sure how many people find this way of looking at things congenial. It is a way of looking at knowledge that has been commonplace among anglo-american philosophers through the 20th century, at least. But as I write it down, I realize how strange it is. In ordinary daily life, knowledge is not regarded as a private pile of chestnuts kept within a cranium. Knowledge is almost always in action, playing an explanatory role in what we do or say or write. On some occasions it is only when we do or say something that we ourselves realize we had some knowledge we didn’t know we had. On other occasions other people see what we are up to, and they say to themselves, “He doesn’t know what he’s doing.”

On ordinary occasions, knowledge is a set of capacities we have, capacities which can be witnessed by others as present. You watch me change a tire, and you see that I know what I’m doing. Sam takes a calculus test and gets a high score. Nelly recounts the history of the Beatles. Juniper fits a cast on a dog’s broken leg. All these people have knowledge, and it is out in the open for anyone to see. Of course there is something going on in their heads—heads are not just ornamental—but the knowledge consists in an agent’s performance, or their capacity to perform, as judged by some kind of audience or measure that indicates their success. It’s not merely “in the head” any more than running is merely “in the legs”.

But even this generous schmearing of knowledge across agents, judges, and environments is too restrictive. For some of our knowledge we possess in virtue of belonging to a group that has that knowledge, loosely speaking. For example, I know humans can colonize Mars. If you press me on this, asking how we would secure a source of water and get plants to grow and protect our living entourage from radiation and hurricane-force winds, my story would crumble pretty quickly. I don’t know those things. My knowledge is based on some loose facts: that we have sent probes to Mars, and humans to the Moon, and I haven’t heard anyone say we could not possibly colonize Mars. That’s just about all I have to offer, and it hardly qualifies me as an expert. But I also believe that if I spent a few weeks doing research or consulting with experts, I could put together a much more detailed account of how we could colonize Mars, perhaps with charts and figures and artist renderings. That is to say, I don’t have the knowledge on me right now, but I could get it for you if you give me a few weeks, because I live in a society where that knowledge is available.

We could play with words and say, for example, that I don’t KNOW we can colonize Mars; I only sort of “know” we can colonize Mars. But I think in most conversations I could make the claim that we can colonize Mars and get virtually no resistance from others, whereas if I assert that we can train monkeys to do brain surgery, I very likely will receive some polite resistance on the matter, even though my knowledge of training monkeys is not appreciably less than my knowledge of establishing a base on Mars. The difference between the two cases is explained by the fact that our society, as a whole, knows how to colonize Mars, and we don’t know how to train monkeys to perform brain surgery. 

Somehow we gain a rough sense of the knowledge that is within our society’s reach, and what is not, though none of us are experts on most matters. Actually, this is no surprise: this is what it is to live in a society rich in knowledge, information, and access. We read and watch and listen and learn, and thus come to a fallible estimation of our collective capacities. One needn’t travel far down the road, geographically or historically, to come across other societies far poorer in their collective knowledge.

We might see if we can organize our knowledge into a series of gradations, extending from what I really know, right here, right now, to knowledge I have as a result of the society I am in. In between these extremes would be layers of things I know something about, or just a little about, or remember knowing at one time, or things about which I know some parts but am confused about others. It would be a complicated, multi-dimensional series, to be sure.  But I want to try to push aside as many complications as possible, and focus on the things we know mostly because we are in a society that knows them. Let’s give this murky area of known things its own distinctive name: educated true opinions.

For example, my knowledge that we can colonize Mars is an educated true opinion. Your knowledge that vaccines reduce the risk of contracting certain diseases is an educated true opinion. Our knowledge that humans are causing global warming is an educated true opinion, and our knowledge that antisemitic conspiracy theories have no factual basis in reality is an educated true opinion. It’s a cumbersome name, but each element is important. I insist on the word “educated” because these opinions are grounded in a roughly accurate sense of what our society collectively knows, even if we as individuals are not able to supply extensive reasons immediately upon request. I insist on the word “true” because I do not wish to say that any of these true opinions are merely opinions that might be true or false: no, they are true. I insist on the word “opinion” because this knowledge concerns matters about which we are not experts.

As the examples I just offered might suggest, many of us end up arguing over educated true opinions. That is, many of us argue over which claims are educated true opinions, and which aren’t. For some of us this arguing is only an occasional pastime. For others it becomes a rage-filled, life-consuming passion. Why it ends up being so important to some people, and not to others, is an interesting question.

One might think any such argument could be settled quite easily by asking some experts to tell us what’s true and what isn’t. But whether we can trust the experts, or even identify them reliably, turns out to be a matter over which there is further disagreement. On many issues we don’t even agree on what it would take to establish a claim as an educated true opinion. Sometimes the arguments become so acrimonious that it can be asked whether we are living in the same society.