[Heidegger’s] books are an embodiment of the idea that philosophy is an impenetrable fog, in which ideas not clearly understood have to be taken on trust. Karl Jaspers was right in seeing this ‘incommunicative’ mode of thought as linked to being dictatorial.
Deference is encouraged by having to take in on trust that the obscure means something important. And since things not understood cannot be argued about, the critical faculties atrophy. Philosophy could not have served the Nazis better than by encouraging deference and by this softening the mind.
– Jonathan Glover, Humanity: A Moral History of the Twentieth Century (1999)