Moral ambiguity creates mental cramps of various sorts, which lead to reflection, discussion, and argument… Morality resists theoretical unification under either a set of special-purpose rules or single general-purpose rule or principle, such as the categorical imperative or the principle of unity. If this is right, and if it is right because the ends of moral life are plural and heterogeneous in kind and because our practices of moral education rightly reflect this, then we have some greater purchase on why the project of finding a single theoretically satisfying moral theory has failed.

Only a theoretical deity is left to any man who has ceased to commune with God, and a theoretical deity saves no man from sin and disheartenment.

The noblest quality and highest in rank of all human activities is philosophy… The philosopher’s aim is his theoretical studies is to ascertain the truth; in his practical knowledge, to conduct himself in accordance with that truth.

[A majority of people] are not theoretical atheists; they are practical atheists. They do not deny the existence of God with their lips, but they are continually denying his existence with their lives.

Will without freedom is an empty word, while freedom is actual only as will, as subject... Mind is in principle thinking, and man is distinguished from beast in virtue of thinking. But it must not be imagined that man is half thought and half will, and that he keeps thought in one pocket and will in another, for this would be a foolish idea. The distinction between thought and will is only that between the theoretical attitude and the practical. These, however, are surely not two faculties; the will is rather a special way of thinking, thinking translating itself into existence, thinking as the urge to give itself existence.

The pace of science forces the pace of technique. Theoretical physics forces atomic energy on us; the successful production of the fission bomb forces upon us the manufacture of the hydrogen bomb. We do not choose our problems, we do not choose our products; we are pushed, we are forced — by what? By a system which has no purpose and goal transcending it, and which makes man its appendix.

Only a theoretical deity is left to any man who has ceased to commune with God and a theoretical deity saves no man from sin and disheartenment.

I am now convinced that theoretical physics is actually philosophy.

I have tried to read philosophers of all ages and have found many illuminating ideas but no steady progress toward deeper knowledge and understanding. Science, however, gives me the feeling of steady progress: I am convinced that theoretical physics is actual philosophy. It has revolutionized fundamental concepts, e.g., about space and time (relativity), about causality (quantum theory), and about substance and matter (atomistics), and it has taught us new methods of thinking (complementarity) which are applicable far beyond physics.

The idea inherent in all idealistic metaphysics–that the world is in some sense a product of the mind–is thus turned into its opposite: the mind is a product of the world, of the processes of nature. Hence, according to popular Darwinism, nature does not need philosophy to speak for her: nature, a powerful and venerable deity, is ruler rather than ruled. Darwinism ultimately comes to the aid of rebellious nature in undermining any doctrine, theological or philosophical, that regards nature itself as expressing a truth that reason must try to recognize. The equating of reason with nature, by which reason is debased and raw nature exalted, is a typical fallacy of the era of rationalization. Instrumentalized subjective reason either eulogizes nature as pure vitality or disparages it as brute force, instead of treating it as a text to be interpreted by philosophy that, if rightly read, will unfold a tale of infinite suffering. Without committing the fallacy of equating nature and reason, mankind must try to reconcile the two.

In traditional theology and metaphysics, the natural was largely conceived as the evil, and the spiritual or supernatural as the good. In popular Darwinism, the good is the well-adapted, and the value of that to which the organism adapts itself is unquestioned or is measured only in terms of further adaptation. However, being well adapted to one’s surroundings is tantamount to being capable of coping successfully with them, of mastering the forces that beset one. Thus the theoretical denial of the spirit’s antagonism to nature–even as implied in the doctrine of interrelation between the various forms of organic life, including man–frequently amounts in practice to subscribing to the principle of man’s continuous and thoroughgoing domination of nature. Regarding reason as a natural organ does not divest it of the trend to domination or invest it with greater potentialities for reconciliation. On the contrary, the abdication of the spirit in popular Darwinism entails the rejection of any elements of the mind that transcend the function of adaptation and consequently are not instruments of self-preservation. Reason disavows its own primacy and professes to be a mere servant of natural selection. On the surface, this new empirical reason seems more humble toward nature than the reason of the metaphysical tradition. Actually, however, it is arrogant, practical mind riding roughshod over the ‘useless spiritual,’ and dismissing any view of nature in which the latter is taken to be more than a stimulus to human activity. The effects of this view are not confined to modern philosophy.

I think this serious and fundamental relation between struggle and truth, the dimension in which philosophy has developed for centuries and centuries, only dramatizes itself, becomes emaciated, and loses its meaning and effectiveness in polemics within theoretical discourse. So in all of this I will therefore propose only one imperative, but it will be categorical and unconditional: Never engage in polemics.

Nor do piecemeal steps however well intended, even partially resolve problems that have reached a universal, global and catastrophic Character. If anything, partial `solutions' serve merely as cosmetics to conceal the deep seated nature of the ecological crisis. They thereby deflect public attention and theoretical insight from an adequate understanding of the depth and scope of the necessary changes.

My conviction has grown so strong that I no longer look on this plan of energy or intelligence transmission as a mere theoretical possibility, but as a serious problem in electrical engineering, which must be carried out some day.

Knowledge of the scriptures is beneficial only when it stimulates a desire for practical realization; otherwise, theoretical knowledge gives one false conviction of wisdom.

The methods of theoretical physics should be applicable to all those branches of thought in which the essential features are expressible with numbers.

The steady progress of physics requires for its theoretical formulation a mathematics which get continually more advanced. ... It was expected that mathematics would get more and more complicated, but would rest on a permanent basis of axioms and definitions, while actually the modern physical developments have required a mathematics that continually shifts its foundation and gets more abstract. Non-Euclidean geometry and non-commutative algebra, which were at one time were considered to be purely fictions of the mind and pastimes of logical thinkers, have now been found to be very necessary for the description of general facts of the physical world. It seems likely that this process of increasing abstraction will continue in the future and the advance in physics is to be associated with continual modification and generalization of the axioms at the base of mathematics rather than with a logical development of any one mathematical scheme on a fixed foundation.

There are, at present, fundamental problems in theoretical physics… the solution of which… will presumably require a more drastic revision of our fundamental concepts than any that have gone before. Quite likely, these changes will be so great that it will be beyond the power of human intelligence to get the necessary new ideas by direct attempts to formulate the experimental data in mathematical terms. The theoretical worker in the future will, therefore, have to proceed in a more direct way. The most powerful method of advance that can be suggested at present is to employ all the resources of pure mathematics in attempts to perfect and generalize the mathematical formalism that forms the existing basis of theoretical physics, and after each success in this direction, to try to interpret the new mathematical features in terms of physical entities.

Science is an essentially anarchic enterprise: theoretical anarchism is more humanitarian and more likely to encourage progress than its law-and-order alternatives.

Experience arises together with theoretical assumptions not before them, and an experience without theory is just as incomprehensible as is (allegedly) a theory without experience.

What is surprising is that almost all the trends that developed within the sciences, Aristotelianism and an extreme Platonism included, produced results, not only in special domains, but everywhere; there exist highly theoretical branches of biology and highly empirical parts of astrophysics. The world is a complex and many-sided thing.