A Priori Quotes

The judgment that human life is worth living, or rather can and ought to be made worth living, ... underlies all intellectual effort; it is the a priori of social theory, and its rejection (which is perfectly logical) rejects theory itself.

Philosophy stands in need of a science which shall determine the possibility, principles, and extent of human knowledge à priori.

The test of a theory is its ability to cope with all the relevant phenomena, not its a priori 'reasonableness'. The latter would have proved a poor guide in the development of science, which often makes progress by its encounter with the totally unexpected and initially extremely puzzling.

The exact sciences, which would be considered a priori as little adapted to women, for example mathematics, astronomy and physics, are exactly those in which thus far they have most distinguished themselves. This contains a warning against too precipitate conclusions about the intellectual life of woman.

What we think of as reality is a continuous synthesis of elements from a fixed hierarchy of a priori concepts and the ever changing data of the senses.

We come now to the question: what is a priori certain or necessary, respectively in geometry (doctrine of space) or its foundations? Formerly we thought everything; nowadays we think nothing. Already the distance-concept is logically arbitrary; there need be no things that correspond to it, even approximately.

Whoever says he is starting from a given in nature may be right, and so is he who says he is starting from nothing!

In this movement of colors I find the essence, which does not arise from a system, or an a priori theory.

Evolutionists ... have a prior commitment, a commitment to materialism. It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door.

It is possible to demonstrate God's existence, although not a priori, yet a posteriori from some work of His more surely known to us.

Any necessary truth, whether a priori or a posteriori, could not have turned out otherwise.

God is the great comprehensive a priori integrity of Universe within which human beings find themselves to be operating.

Upon the solution of this problem, or upon sufficient proof of the impossibility of synthetical knowledge a priori, depends the existence or downfall of metaphysics.

No code of ethics and no effort are justifiable a priori in the face of the cruel mathematics that command our condition.

Science has been effective at furthering our understanding of nature because the scientific ethos is based on three key principles: (1) follow the evidence wherever it leads; (2) if one has a theory, one needs to be willing to try to prove it wrong as much as one tries to prove that it is right; (3) the ultimate arbiter of truth is experiment, not the comfort one derives from one's a priori beliefs, nor the beauty or elegance one ascribes to one's theoretical models.

But although all our knowledge begins with experience, it does not follow that it arises from experience.

Whether arrived at through reason or revelation, natural law is the highest law known to man. It is anchored in the very existential nature of man and is therefore a priori just.

Nothing can better express the feelings of the scientist towards the great unity of the laws of nature than in Immanuel Kant's words: "Two things fill the mind with ever new and increasing awe: the stars above me and the moral law within me."... Would he, who did not yet know of the evolution of the world of organisms, be shocked that we consider the moral law within us not as something given, a priori, but as something which has arisen by natural evolution, just like the laws of the heavens?