Max Weber, “Science as a Vocation”, in Max Weber’s Complete Writings on Academic and Political Vocations, ed. John Dreijmanis (New York: Algora Publishing, 2008), 41-43:

Let us now focus our attention on the disciplines with which I am most closely concerned; that is, sociology, history, political economy and political science and those varieties of cultural philosophy whose function is to interpret them. It has been said, and I support this, that politics has no place in the lecture hall. It is out of place there when students introduce it. I would, for example, find it deplorable if, say, pacifist students surrounded my former colleague Dietrich Schäfer in Berlin in one of his lectures and created a disturbance, and I would find it equally deplorable if, as is said to have occurred, anti-pacifist students behaved in the same way toward Professor [Friedrich W.] Förster, although my views are in many respects as far from his as it is possible to be. But neither does politics have any place in the lecture hall when the lecturer introduces it. Least of all, when his own particular subject is political science. Views regarding issues of practical politics and scientific analysis of political structures and party positions are two quite different matters. If someone speaks about democracy in a public meeting, he should make no secret of his personal point of view. It is his confounded duty and obligation to take a clear partisan position. The words used are then not a means of scientific analysis, but of political campaigning to win over others to his point of view. They are not plowshares to break up the soil of contemplative thought, but swords to use against the adversary. They are weapons in the struggle.

In a lecture or in a lecture hall, on the other hand, it would be an outrage to use words in this way. In that situation, where the topic is “democracy,” for example, one will take the different forms of democracy and analyze them to establish how they function, and what particular consequences each has for the conditions of life, and then contrast them with other, non-democratic, forms of political order and attempt to reach the point at which the listener himself can adopt a stance in the light of his ultimate ideals. But the genuine teacher, speaking from the lectern, will take great care not to force any point of view on him, whether explicitly or by suggestion, while claiming to “let the facts speak for themselves,” which would naturally be a most underhand tactic.

But why should we not do this? I admit that many highly esteemed colleagues are of the opinion that such self-denial is not feasible, and if it were practiced it would be a mere eccentricity and should be avoided. Now, one cannot demonstrate scientifically what the duty of an academic teacher should be. One can only demand from him the intellectual integrity to be clear about the difference between, on the one hand, establishing facts, mathematical or logical states of affairs, or establishing the internal structure of cultural values, and on the other hand, answering the question of the value of culture and of its individual contents, followed by the question of how one should act within the cultural community and political associations. These are two entirely heterogeneous problems. If he goes on to ask why he should not deal with both in the lecture hall, the answer is because the prophet and the demagogue have no place at the lectern in the lecture hall. The message to both the prophet and the demagogue is: “Go out on the streets and speak publicly,” which is to say, go where criticism is possible. In the lecture hall the teacher sits facing an audience who are obliged to attend his lectures for the sake of their careers and remain silent while he speaks. I regard it as irresponsible if instead of giving his listeners the benefit of his knowledge and scientific experience, which is his duty, he takes advantage of a situation where there is no one there who can criticize him and attempts to impose his political views on them. No doubt, it may be impossible for the individual to disregard his subjective sympathies entirely, but he must then face the severest criticism in the forum of his own conscience. Promoting his own views confirms nothing, as purely factual errors are also possible. Yet, they attest nothing against his duty to seek the truth. I am therefore against this approach, not least in the interests of science. I am prepared to demonstrate, from the works of our historians, that whenever the man of science puts forward his own value judgment, full understanding of the facts ceases. But this subject is beyond the scope of this evening’s topic and would call for lengthy discussion.