A great analysis by Polanyi of the cultural structure that maintains (or at least maintained) Marxism:

This is the characteristic structure of what I shall call a dynamo-objective coupling. Alleged scientific assertions, which are accepted as such because they satisfy moral passions, will excite these passions further, and thus lend increased convincing power to the scientific affirmations in question—and so on, indefinitely. Moreover, such a dynamo-objective coupling is also potent in its own defence. Any criticism of its scientific part is rebutted by the moral passions behind it, while any moral objections to it are coldly brushed aside by invoking the inexorable verdict of its scientific findings. Each of the two components, the dynamic and the objective, takes it in turn to draw attention away from the other when it is under attack.

We can see that this structure underlies also a logical fallacy exposed by the academic critics of Marxism, and explains why the fallacy survives its exposure. The critics say that no political programme can be derived from the Marxian prediction of the inevitable destruction of Capitalism at the hands of the proletariat. For it is senseless to enlist fighters for a battle which is said to be already decided; while if the battle is not yet decided, you cannot predict its issue. But within a dynamo-objective coupling, the logical objection against using a historical prediction as an appeal to fight for the certain outcome of history no longer arises. For the prediction is accepted only because we believe that the Socialist cause is just; and this implies that Socialist action is right. The prediction implies therefore a call to action.

— Michael Polanyi, Personal Knowledge: Toward a Post-Critical Philosophy, 230–31