The pseudo rationalists do true rationalism a disservice if they pretend to have adequate insight exactly where strict rationalism excludes it on purely logical grounds. Rationalism sees its chief triumph in the clear recognition of the limits of actual insights.
Otto Neurath, ‘The Lost Wanderers of Descartes and the Auxiliary Motive’, in Philosophical Papers, 1913-1946, Dordrecht, 1983, p. 8
The basic presupposition shared by Heidegger and other philosophers in the rational-metaphysical tradition from Plato and Aristotle onwards is that the central metaphysical question is a Why-question, and is about the reason or reasons that explain why everything is and is as it is. Metaphysicians from Plato to Hegel presupposed the most fundamental metaphysical truth to be the answer to this question, and metaphysicians from Schopenhauer onwards presupposed the most basic metaphysical truth to be the unanswerability of this question.
Quentin Smith, The Felt Meanings of the World: A Metaphysics of Feeling, West Lafayette, Indiana, 1986, p. 13
I shall die […] as I have lived, rationalist, socialist, pacifist, and humanitarian[.]
Henry Salt, quoted in George Hendrick, Henry Salt: Humanitarian Reformer and Man of Letters, Illinois, 1977