Epistemic unity among inquirers is an important goal of all inquiry. We strive to arrive at the same opinion on a given subject. We try to eliminate diversity of opinion, divergence of belief. The conscientious inquirer seeks consensus, convergence, homogeneity of belief. To this end we employ methods that reliably lead to identity of belief among inquirers; a method that reliably leads to belief divergence would ipso facto be defective. Why do we do this? Because reality itself is a unity, a single way things are. Truth is exclusive: what is true rules out what is false. If it’s true that snow is white, then it’s false that snow is purple; and if some people believe the latter, then their beliefs are false. Truth is not inclusive of the false. Since we aim at true belief we aim at unity of belief, because truth itself is unitary. Truth and epistemic unity go hand in hand. If there were many conflicting truths (snow is both white and purple), then epistemic unity would not be a value; on the contrary, we would strive for epistemic plurality. It is the same with logical validity: only one conclusion follows from a given set of premises. We can’t infer both p and not-p from the same set of premises. Logic excludes certain inferences while including others. To put it differently, the enterprise of knowledge is inherently exclusive and unitary, not inclusive and diverse. This is why we have refutation and falsification—in order to weed out error and falsehood. The enterprise of acquiring knowledge is inherently rejecting and selective, not accepting and indiscriminate—indeed, it must be discriminative (with respect to belief not people). Inevitably this will lead to distress, disappointment, and discomfort: it’s hard to see your pet theory refuted! But that is the nature of the game: the ideal of epistemic unity guarantees it. Ideally, then, everyone will in the end share the same set of beliefs—those that correspond to reality (which is necessarily one way rather than another). Rationality itself prescribes interpersonal identity of belief, a single right way to believe. Differences of opinion are contrary to the dictates of reason, i.e. when they concern matters of fact. Reason does not welcome all viewpoints; it opposes some viewpoints and favors others. In an ideal world everybody would agree. We might think of human history as a gradual progression towards complete epistemic unity, in which all divergence, disagreement, and diversity have been expunged. We are all one, epistemologically speaking, or should be.
What I have just said is mere truism—a set of platitudes about truth, reason, belief, and intellectual inquiry. But notice how it conflicts with a rhetoric that emphasizes diversity, inclusiveness, and equality. The enterprise of knowledge is against those values if applied to the methods of rational inquiry: it recommends unity, exclusivity, and inequality (beliefs are not equal one of them is false). Of course, it may accept such values if intended differently, but it will insist that the opposite values must obtain in the sphere of intellectual endeavor. It will certainly object to any effort to bolster those different aims by appeal to the nature of rational inquiry itself. Aiming at identity of belief is not aiming at other sorts of identity. What is interesting is that the exclusive and homogenizing nature of rational inquiry can (and must) coexist with recognizing other sorts of diversity and inclusiveness. The two must not be muddled or glossed over. It is entirely consistent to insist on stringent adherence to unity and exclusiveness in intellectual matters while accepting that disunity and inclusiveness can operate along other dimensions. The community of inquirers seeks unity of belief but not unity of race, sex, sexual preference, taste in music, height, pulchritude, and so on. Of course, the exclusionary aspects of truth and knowledge may be upsetting to some—it may not cater to their “wellness” or “comfort level” or sense of “safety”. But knowledge is not in the business of therapy: knowledge does not seek to soothe or flatter or condone. These are completely different enterprises: a university may cater to one, a hospital to another. A teacher is not a therapist. And there is no escaping the fact that rational inquiry is inherently “discriminatory”: it seeks to discriminate the true from the false, the justified from the unjustified. It has no “tolerance” for error. It sets its face against diversity of belief, if that means allowing false belief to flourish. Education is the dissemination of shared true belief, not the celebration of divergent beliefs. An education in geography, say, is not “open” to divergent geographical beliefs, allowing for the belief that Africa is smaller than England. Education forms an exclusive club—those that have it and those that don’t. This applies as much to electricians and plumbers as university professors (you don’t want much diversity of electrical knowledge if your power goes out). Students need to understand that they are being initiated into an exclusive fraternity that prizes a specific type of knowledge. They should also understand that cognitive identity is the aim of the education they receive: they are to be brought to be identical to each other with respect to knowledge. Despite other differences, they converge in this one vital respect—what they know. This unites them. So the unity of knowledge brings about social unity—an important value. It should not be forgotten or occluded or demonized: people can be brought together by means of education provided that it is recognized that epistemic unity is possible and desirable. In a world in which irresoluble diversity of opinion is deemed tolerable and even celebrated the virtues and benefits of shared knowledge will be lost. We should insist on fostering epistemic unity not questioning it. Exclusiveness, unity, inequality!
 Of course there can be culinary or aesthetic differences of opinion, and it is often not easy to discern the truth, but this doesn’t undermine the idea that we should seek convergence of belief, i.e. convergence on the objective facts of the matter. Epistemic unity is a “regulative ideal”.
 I would put moral education and moral knowledge at the top of the list. Moral belief does and should operate exclusively, ruling out immoral or evil beliefs. Ideally, all moral beings should agree in their moral convictions. And not all moral beliefs are equal: some are better than others. Determining the correct morality is another matter, but moral knowledge seeks epistemic unity, like all knowledge.