Philosophy has to do with many things, but historically the major ones have been three big questions: What’s real? How do we know what’s real? And what shall we do about what’s real? This essay is about the second of these questions.

I was recently asked what is the most important thing to know. You could answer this in many ways. You could say that the most important thing is to know what’s real so that your actions will be based on reality and thus likely to be successful. Or you could say that the most important thing is to know what to do about what’s real, because acting without that knowledge could lead you astray in the maze of life’s moral perplexities. But I think the best answer has to do with the second big question.

The most important thing to know is how to know. By “how to know” I mean how to acquire true beliefs and be assured that they are true. I could restate this idea in a number of ways. The most important thing to know is how to tell whether what you think you know is true or not; how to tell whether you really know what you think you know; how to tell what is true; how to acquire accurate knowledge; or how to tell when you are really knowing rather than just believing.

The word “know” implies having true beliefs. If what you think you know turns out to be wrong, then you find out that you had false beliefs, not knowledge. There is more to knowledge than just true beliefs, however, as Plato suggested in the Meno more than two thousand years ago. Plato has a charming metaphor: He likens mere belief to the magical statues of Daedalus, which move around if not fastened down. If you don’t tie them down, they are worthless because they wander away. But if you do tie them down, you get to enjoy their magnificent beauty.⁽¹⁾

Similarly, if you just have true beliefs but don’t know what makes them true, then you are at risk of losing them. Someone might come along with a plausible but false argument against them, or someone who seems to have authority might tell you something different. But if you know how you came to your beliefs, if you know what led you to believe them and can retrace your steps of reasoning, then you can withstand the wiles of those with glib tongues and the pronouncements of so-called experts. As Plato says,

True opinions are a fine thing and do all sorts of good so long as they stay in their place, but they will not stay long. They run away from a [person]’s mind, so they are not worth much until you tether them by a chain….Once they are tied down, they become knowledge, and are stable.⁽²⁾

Plato, at least in the Meno, considers this tether to be recollection of an immutable realm of knowledge that we knew before we were born. Today we can take it to be a chain of reasoning or the working out of a solution. The point is that if you know how you came to your beliefs, if you know what led you to believe them, then you can retrace that chain of reasoning whenever you need to. Your true beliefs are both more stable in your mind and more worthy of your confidence in them.

And stability is important because of what knowledge is for: to guide our actions in the world. Without accurate knowledge we cannot succeed in doing what we intend. True beliefs enable us to succeed, and knowledge—true beliefs that we can justify—enable us to succeed time and time again.

We know how to acquire true beliefs about the physical world: by using the scientific method, which is a formal, systematic way to gather and assess evidence and to check what people say about reality. It minimizes the influence of bias and prejudice, and it results in a representation of the world that is reliable, non-arbitrary and consistent. With it we have made great progress in understanding and mastery.

The physical world is not the only realm we need to master. Perhaps more important is the social realm of the people we live, play and work with. Here, the scientific method helps us less. Psychology, anthropology and sociology can tell us facts about how people behave, but facts alone are not as valuable as practical interpersonal skills, skills which we learn by growing up in the company of others. It’s not so much a chain of reasoning that anchors our true beliefs but the informal evidence of our experience. We know that an acquaintance is trustworthy or not because of our past interactions with that person. Or because of that person’s reputation, what others tell us about him or her. Unfortunately what others tell us can be wrong, particularly when it reflects social prejudice. If we don’t apply critical thinking to social judgments against, for instance, people of a different race or creed or ethnicity or sexual orientation, then we risk doing harm to those people or at least missing out on rewarding interactions. In the social as well as the physical realm we need to figure out how to find the truth.

And we need to understand ourselves too. We need to understand how our thinking works. Much of our everyday thinking, as opposed to theoretical reasoning, is based on intuition, which consists of rapid judgments that we make without much deliberate thought. But sometimes intuition doesn’t work. Daniel Kahneman, a Nobel-prize-winning psychologist, has described at length many of the ways our cognitive apparatus fails to provide accurate results. In Thinking, Fast and Slow he describes a surprisingly large array of cognitive biases with names such as “availability heuristic,” “affect heuristic,” “confirmation bias,” “halo effect” and the like. His hope is that if we put names on them we will be more likely to spot them when they crop up. The evidence of our immediate intuition is unreliable, so we have to think critically about it.

Using the scientific method; reflecting critically on how we acquire social knowledge; and paying attention, as best we can, to our own intuitive biases: these are all ways of knowing how to know. A common theme runs through them, the need to observe reality carefully and to assess our evidence critically.

Knowing is one of the things we humans do best; by paying attention to our own thinking we learn to think better. Without accurate knowledge we risk believing what is false and failing in our endeavors. Hence, knowing how to know is the most important thing to know.

——

Notes

(1) Meno, 97d-e.

(2) Meno, 97e-98a.

References

Kahneman, Daniel. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux, 2011.

Plato, Meno. Tr. W.K.C. Guthrie. The Collected Dialogues of Plato, Ed. Edith Hamilton and Huntington Cairns. New York: Pantheon Books, 1963.