Created from Animals: The Moral Implications of Darwinism (1990), p. 5
“If rational thought thinks itself out to a conclusion, it arrives at something non-rational which, nevertheless, is a necessity of thought. This is the paradox which dominates our spiritual life. If we try to get on without this non-rational element, there result views of the world and of life which have neither vitality nor value.”
Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics
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Albert Schweitzer 126
French-German physician, theologian, musician and philosoph… 1875–1965Related quotes
Anatol Rapoport. (1974). Game Theory as a Theory of Conflict Resolution p. 4
1970s and later

Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics
Context: The restoration of our world-view can come only as a result of inexorably truth-loving and recklessly courageous thought. Such thinking alone is mature enough to learn by experience how the rational, when it thinks itself out to a conclusion, passes necessarily over into the non-rational. World- and life-affirmation and ethics are non-rational. They are not justified by any corresponding knowledge of the nature of the world, but are the disposition in which, through the inner compulsion of our will-to-live, we determine our relation to the world.
What the activity of this disposition of ours means in the evolution of the world, we do not know. Nor can we regulate this activity from outside; we must leave entirely to each individual its shaping and its extension. From every point of view, then, world- and life-affirmation and ethics are non-rational, and we must have the courage to admit it.

Source: Economic Analysis of Law (7th ed., 2007), Ch. 1: The Nature of Economic Reasoning

Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics
Context: Affirmation of the world, which means affirmation of the will-to-live that manifests itself around me, is only possible if I devote myself to other life. From an inner necessity, I exert myself in producing values and practising ethics in the world and on the world even though I do not understand the meaning of the world. For in world- and life-affirmation and in ethics I carry out the will of the universal will-to-live which reveals itself in me. I live my life in God, in the mysterious divine personality which I do not know as such in the world, but only experience as mysterious Will within myself.
Rational thinking which is free from assumptions ends therefore in mysticism. To relate oneself in the spirit of reverence for life to the multiform manifestations of the will-to-live which together constitute the world is ethical mysticism. All profound world-view is mysticism, the essence of which is just this: that out of my unsophisticated and naïve existence in the world there comes, as a result of thought about self and the world, spiritual self-devotion to the mysterious infinite Will which is continuously manifested in the universe.

The Tragic Sense of Life (1913), II : The Starting-Point

Quoted in “Collected works of Periyar E.V.R.” p. 511.
Rationalism

La doctrine économique d'Adam Smith, c'est la doctrine de Mandeville, exposée sous une forme non plus paradoxale et littéraire, mais rationnelle et scientifique.
Élie Halévy La formation du radicalisme philosophique (Paris: F. Alcan, 1901-4) vol. 1, p. 162; Mary Morris (trans.) The Growth of Philosophic Radicalism (Clifton, N.J.: A. M. Kelley, 1972) p. 90.
Criticism