[Excerpt from his new book, The Constitution of Knowledge: A Defense of Truth, published by Brookings Institution Press.]

When Americans think about how we find truth amid a world full of discordant viewpoints, we usually turn to a metaphor, that of the marketplace of ideas. It is a good metaphor as far as it goes, yet woefully incomplete. It conjures up an image of ideas being traded by individuals in a kind of flea market, or of disembodied ideas clashing and competing in some ethereal realm of their own. But ideas in the marketplace do not talk directly to each other, and for the most part neither do individuals. 

Rather, our conversations are mediated through institutions like journals and newspapers and social-media platforms. They rely on a dense network of norms and rules, like truthfulness and fact-checking. They depend on the expertise of professionals, like peer reviewers and editors. The entire system rests on a foundation of values: a shared understanding that there are right and wrong ways to make knowledge. Those values and rules and institutions do for knowledge what the U.S. Constitution does for politics: They create a governing structure, forcing social contestation onto peaceful and productive pathways. And so I call them, collectively, the Constitution of Knowledge. If we want to defend that system from its many persistent attackers, we need to understand it—and its very special notion of reality.

What reality really is

The question “What is reality?” may seem either too metaphysical to answer meaningfully or too obvious to need answering. Colloquially, people also use the terms “real” and “reality” to convey certainty or confidence that things are the way they are. Reality, in common parlance, is that which is reliable and intractable and cannot be wished away: the rock we stub our toe on, the abrupt encounter with the ground when we fall. 

Such colloquial definitions are not very helpful. The whole problem is that humans have no direct access to an objective world independent of our minds and senses, and subjective certainty is no guarantee of truth. Faced with those problems and others, philosophers and practitioners think of reality as a set of propositions (or claims, or statements) that have been validated in some way, and that have thereby been shown to be at least conditionally true—true, that is, unless debunked. Some propositions reflect reality as we perceive it in everyday life (“The sky is blue”). Others, like the equations on a quantum physicist’s blackboard, are incomprehensible to intuition. Many fall somewhere in between.

Now, you must have noticed that a phrase I used a few sentences ago, “validated in some way,” hides a cheat. In epistemology, the whole question is, validated in what way? If we care about knowledge, freedom, and peace, then we need to stake a strong claim: Anyone can believe anything, but liberal science—open-ended, depersonalized checking by an error-seeking social network—is the only legitimate validator of knowledge, at least in the reality-based community. Other communities, of course, can do all kinds of other things. But they cannot make social decisions about objective reality.

That is a very bold, very broad, very tough claim, and it goes down very badly with lots of people and communities who feel ignored or oppressed by the Constitution of Knowledge: creationists, Christian Scientists, homeopaths, astrologists, flat-earthers, anti-vaxxers, birthers, 9/11 truthers, postmodern professors, political partisans, QAnon followers, and adherents of any number of other belief systems and religions. It also sits uncomfortably with the populist and dogmatic tempers of our time. But, like the U.S. Constitution’s claim to exclusivity in governing (“unconstitutional” means “illegal,” period), the Constitution of Knowledge’s claim to exclusivity is its sine qua non.

Rules for reality

Say you believe something (X) to be true, and you believe that its acceptance as true by others is important or at least warranted. X might be that the earth revolves around the sun, that God is a trinity, that an embryo is a human being, that human activity is causing climate change, that vaccination saves lives, that Joe Biden was lawfully elected president, or some other consequential proposition. The specific proposition does not matter. What does matter is that the only way to validate it is to submit it to the reality-based community. Otherwise, you could win dominance for your proposition by, say, brute force, threatening and jailing and torturing and killing those who see things differently—a standard method down through history. Or you and your like-minded friends could go off and talk only to each other, in which case you would have founded a cult—which is lawful but socially divisive and epistemically worthless. Or you could engage in a social-media campaign to shame and intimidate those who disagree with you—a very common method these days, but one that stifles debate and throttles knowledge (and harms a lot of people).

What the reality-based community does is something else again. Its distinctive qualities derive from two core rules: 

The fallibilist rule: No one gets the final say. You may claim that a statement is established as knowledge only if it can be debunked, in principle, and only insofar as it withstands attempts to debunk it. That is, you are entitled to claim that a statement is objectively true only insofar as it is both checkable and has stood up to checking, and not otherwise. In practice, of course, determining whether a particular statement stands up to checking is sometimes hard, and we have to argue about it. But what counts is the way the rule directs us to behave: You must assume your own and everyone else’s fallibility and you must hunt for your own and others’ errors, even if you are confident you are right. Otherwise, you are not reality-based.

The empirical rule: No one has personal authority. You may claim that a statement has been established as knowledge only insofar as the method used to check it gives the same result regardless of the identity of the checker, and regardless of the source of the statement. Whatever you do to check a proposition must be something that anyone can do, at least in principle, and get the same result. Also, no one proposing a hypothesis gets a free pass simply because of who she is or what group she belongs to. Who you are does not count; the rules apply to everybody and persons are interchangeable. If your method is valid only for you or your affinity group or people who believe as you do, then you are not reality-based.

Both rules have very profound social implications. “No final say” insists that to be knowledge, a statement must be checked; and it also says that knowledge is always provisional, standing only as long as it withstands checking. It rejects the possibility of any ultimate authority—any priest, prince, or politburo—who can dictate truth or legitimately enforce intellectual conformity.

“No personal authority” adds a crucial second step by defining what properly counts as checking. The point, as the great American philosopher Charles Sanders Peirce emphasized more than a century ago, is not that I look or you look but that we look; and then we compare, contest, and justify our views. Critically, then, the empirical rule is a social principle that forces us into the same conversation—a requirement that all of us, however different our viewpoints, agree to discuss what is in principle only one reality.

By extension, the empirical rule also dictates what does not count as checking: claims to authority by dint of a personally or tribally privileged perspective. In principle, persons and groups are interchangeable. If I claim access to divine revelation, or if I claim the support of miracles that only believers can witness, or if I claim that my class or race or historically dominant status or historically oppressed status allows me to know and say things that others cannot, then I am breaking the empirical rule by exempting my views from contestability by others.

Though seemingly simple, the two rules define a style of social learning that prohibits a lot of the rhetorical moves we see every day. Claiming that a conversation is too dangerous or blasphemous or oppressive or traumatizing to tolerate will almost always break the fallibilist rule. Claims which begin “as a Jew,” or “as a queer,” or for that matter “as minister of information” or “as Pope” or “as head of the Supreme Soviet,” can be valid if they provide useful information about context or credentials; but if they claim to settle an argument by appealing to personal or tribal authority, rather than earned authority, they violate the empirical rule. 

“No personal authority” says nothing against trying to understand where people are coming from. If we are debating same-sex marriage, I may mention my experience as a gay person, and my experience may (I hope) be relevant. In fact, good scientific practice requires researchers to disclose their personal equities so as to surface conflicts of interest. But statements about personal standing and interest inform the conversation; they do not control it, dominate it, or end it. The rule acknowledges, and to an extent accepts, that people’s social positions and histories matter; but it asks its adherents not to burrow into their social identities, and not to play them as rhetorical trump cards, but to bring them to the larger project of knowledge-building and thereby transcend them.

There is more, much more, that distinguishes the Constitution of Knowledge from traditional, tribal, and tyrannical epistemic regimes. But the fallibilist and empirical rules are the common basis of science, journalism, law, and all the other branches of today’s reality-based community. For that reason, both rules also attract hostility, defiance, interference, and open warfare from those who would rather manipulate truth than advance it.

Jonathan Rauch is a senior fellow at the Brookings Institution and the author of The Constitution of Knowledge: A Defense of Truth.