A doctrinaire is a fool but an honest man.
A doctrine serves no purpose in itself, but it is indispensable to have one if only to avoid being deceived by false doctrines.
A faith is something you die for, a doctrine is something you kill for. There is all the difference in the world.
A striking feature of moral and political argument in the modern world is the extent to which it is innovators, radicals, and revolutionaries who revive old doctrines, while their conservative and reactionary opponents are the inventors of new ones.
It was then that I began to look into the seams of your doctrine. I wanted only to pick at a single knot; but when I had got that undone, the whole thing raveled out. And then I understood that it was all machine-sewn.
The American doctrinaire is the converse of the American demagogue, and, in this way, is scarcely less injurious to the public. The first deals in poetry, the last in cant. He is as much a visionary on one side, as the extreme theoretical democrat is a visionary on the other.
The greatest horrors in the history of mankind are not due to the ambition of the Napoleons or the vengeance of the Agamemnons, but to the doctrinaire philosophers. The theories of the sentimentalist Rousseau inspired the integrity of the passionless Robespierre. The cold-blooded calculations of Karl Marx led to the judicial and business-like operations of the Cheka.