[The following are three excerpts from Martin Heidegger's Letter on Humanism]
Absolute metaphysics, with its Marxian and Nietzschean inversions, belongs to the history of the truth of being. Whatever stems from it cannot be countered or even cast aside by refutations. It can only be taken up in such a way that its truth is more primordially sheltered in Being itself and removed from the domain of mere human opinion. All refutation in the field of essential thinking is foolish. Strife among thinkers is the "lovers' quarrel" concerning the matter itself. It assists them mutually toward a simple belonging to the Same, from which they find what is fitting for them in the destiny of Being. (p. 239, Basic Works)
However, as long as philosophy merely busies itself with continually obstructing the possibility of admittance into the matter for thinking, i.e., into the truth of Being, it stands safely beyond any danger of shattering against the hardness of that matter. Thus to "philosophize" about being shattered is seperated by a chasm from a thinking that is shattered. If such thinking were to go fortunately for a man, no misfortune would befall him. He would receive the only gift that can come from thinking from Being. (p. 246, Basic Works)
Should we not rather suffer a little while longer those inevitable misinterpretations to which the the path of thinking in the element of Being and time has hitherto been exposed and let them slowly dissipate? These misinterpretations are natural reinterpretations of what was read, or simply mirrorings of what one believes he knows already before he reads. They all betray the same structure and the same foundation.
Because we are speaking against "humanism" people fear a defense of the inhuman and a glorification of barbaric brutality. For what is more "logical" than that for somebody who negates humanism nothing remains but the affirmation of inhumanity?
Because we are speaking against "logic" people believe we are demanding that the rigour of thinking be denounced and in its place the arbitrariness of drives and feelings be proclaimed as true. For what is more "logical" than that whoever speaks against the logical is defending the alogical?
Because we are speaking against "values" people are horrified at a philosophy that ostensibly dares to despise humanity's best qualities. For what is more "logical" than that a thinking that denies values must necessarily pronounce everything valueless?
We are so filled with "logic" that anything that disturbs the habitual somnolence of prevailing opinion is automatically registered as a despicable contradiction. We pitch everything that does not stay close to the familiar and beloved positive into the previously excavated pit of pure negation, which negates everything, ends in nothing, and so consumates nihilism. Following this logical course we let everything expire in a nihilism we invented for ourselves with the aid of logic.
But does the "against" which thinking advances against ordinary opinion necessarily point toward pure negation and the negative? This happens -- and then, to be sure, happens inevitably and conclusively, that is, without a clear prospect of anything else -- only when one posits in advance what is meant by the "positive" and on this basis makes an absolute and absolutely negative decision about the range of possible opposition to it. Concealed in such a procedure is the refusal to subject to reflection this presupposed "positive" in which one believes oneself saved, together with its position and opposition. By continually appealing to the logical one conjures up the illusion that one is entering straightforwardly into thinking when in fact one has disavowed it. (p. 249, Basic Works)