In an age which values certainty, it may seem odd to extol the merits of not knowing. Yet it is precisely because of the deep need for certainty, in a time when that is increasingly elusive, that the question must be asked: how do we know what we think we know?

Certainly, we can be led astray by emotion, but reason too can mislead. Formulating propositions that are supposed to be either true or false suggests that things can be known with definite certainty. We are trained in school to answer true-or-false questions on exams. But only statements are true or false, never reality itself. At a given moment, it may seem reasonable to suppose that either it is raining or it is not. But when you step outdoors and feel a single drop of moisture on your face, is it then raining or not? The question may only matter if you are trying to decide whether to take your umbrella. The point of certainty is to decide a course of action.

We are all familiar with the maddening limitations of public surveys, which ask you to rate your agreement with various propositions. Such “multiple choice” questions are also familiar from school days. Expanding the number of categories beyond two may seem like an improvement, but the crucial fact remains that all categories are artificial. In the case of surveys, our replies are used by others to make decisions that matter—to them, and potentially to us. While such information may reflect how people actually think and act, haven’t you wished you could give more nuanced answers? In some ways, the survey is an apt metaphor for our own internal thought processes. We poll ourselves to decide some issue that could require action. But then we tend to think in words, which means in either/or terms and forced categories.

The essence of digitation is formally known as the law of excluded middle: there is no ground between ‘on’ and ‘off’. But these are categories designed to force the issue, to artificially create the certainty upon which to act decisively. (“Either you are for us or against us.”) In many cases this serves society well. It’s why digital files can be copied without error. Even if we cannot predict the weather perfectly, digitation enables us to send spacecraft millions of miles to rendezvous with a precise location. Yet, no plan or calculation ever corresponds perfectly to reality, which can surprise us because it is always more nuanced than we think. Probability and statistics help to compensate for this limitation of thought in relation to the naturally ambiguous real world. Yet, even they deal with events that are presumed either to have happened or not. Reason depends on categories and operations that are clearly defined—putting reality aside. While thought aims at certainty, it also presumes it.

Certainty is a state of mind, not a state of the world. We hope to feel certain when action is required, since being wrong (or failing to act) can have dire consequences. Yet, however right we feel, mistakes are possible. Sometimes it is better to do nothing than to act prematurely. In some situations, it is wise to doubt what the situation actually is, because the reality is never as clear and simple as we think or others say. Psychologically, however, it is very challenging to remain in doubt, since it goes against a fundamental requirement to feel settled and decisive. A different skill is required.

I do not envy people in positions of authority who must make weighty and timely decisions. Errors of judgment often involve false assumptions and poor information (such as rumor). An underlying problem is knowing when to trust one’s mind and one’s information. Though not always possible, deferring judgment makes time for self-examination as well as further examination of the data.