“Even a statement very close to the periphery can be held true in the face of recalcitrant experience by pleading hallucination or by amending certain statements of the kind called logical laws. Conversely, by the same token, no statement is immune to revision. Revision even of the logical law of the excluded middle has been proposed as a means of simplifying quantum mechanics; and what difference is there in principle between such a shift and the shift whereby Kepler superseded Ptolemy, or Einstein Newton, or Darwin Aristotle?”

Source: 1920s, Kritische Theorie der Formbildung (1928, 1933), p. 91; as cited in: M. Drack, W. Apfalter, D. Pouvreau (2007) " On the making of a system theory of life: Paul A Weiss and Ludwig von Bertalanffy's conceptual connection http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874664/". in: Q Rev Biol. 2007 December; 82(4): 349–373.

The Fundamental Equations for Electromagnetic Processes in Moving Bodies (1907)

Rudolf Carnap (1937) cited in: Irving J. Lee (1967) The Language of Wisdom and Folly: Background Readings in Semantics. International Society for General Semantics, p. 44

Source: The Logic of Scientific Discovery (1934), Ch. 1 "A Survey of Some Fundamental Problems", Section I: The Problem of Induction
Context: A principle of induction would be a statement with the help of which we could put inductive inferences into a logically acceptable form. In the eyes of the upholders of inductive logic, a principle of induction is of supreme importance for scientific method: "… this principle", says Reichenbach, "determines the truth of scientific theories. To eliminate it from science would mean nothing less than to deprive science of the power to decide the truth or falsity of its theories. Without it, clearly, science would no longer have the right to distinguish its theories from the fanciful and arbitrary creations of the poet's mind."
Now this principle of induction cannot be a purely logical truth like a tautology or an analytic statement. Indeed, if there were such a thing as a purely logical principle of induction, there would be no problem of induction; for in this case, all inductive inferences would have to be regarded as purely logical or tautological transformations, just like inferences in inductive logic. Thus the principle of induction must be a synthetic statement; that is, a statement whose negation is not self-contradictory but logically possible. So the question arises why such a principle should be accepted at all, and how we can justify its acceptance on rational grounds.

Source: Carnap’s intellectual biography (1963), p. 25 as cited in: M. J. Cresswell (2010) " Carnap's logic http://apacentral.org/necessity/Cresswell_Carnap.pdf"

Great Books: The Foundation of a Liberal Education (1954)

Source: The Flame is Green (1971), Ch. 5 : Muerte De Boscaje

Indian Spirituality and Life (1919)
Context: To the Indian mind the least important part of religion is its dogma; the religious spirit matters, not the theological credo. On the contrary to the Western mind a fixed intellectual belief is the most important part of a cult; it is its core of meaning, it is the thing that distinguishes it from others. For it is its formulated beliefs that make it either a true or a false religion, according as it agrees or does not agree with the credo of its critic. This notion, however foolish and shallow, is a necessary consequence of the Western idea which falsely supposes that intellectual truth is the highest verity and, even, that there is no other. The Indian religious thinker knows that all the highest eternal verities are truths of the spirit. The supreme truths are neither the rigid conclusions of logical reasoning nor the affirmations of credal statement, but fruits of the soul's inner experience. Intellectual truth is only one of the doors to the outer precincts of the temple. And since intellectual truth turned towards the Infinite must be in its very nature many-sided and not narrowly one, the most varying intellectual beliefs can be equally true because they mirror different facets of the Infinite. However separated by intellectual distance, they still form so many side-entrances which admit the mind to some faint ray from a supreme Light. There are no true and false religions, but rather all religions are true in their own way and degree. Each is one of the thousand paths to the One Eternal.