In addition to these systematic formulae of fideism, we find throughout the history of philosophy from the time of the sophists to the present day a fideistic attitude of mind, which became more or less conspicuous at different periods. Fideism owes its origin to distrust in human reason, and the logical sequence of such an attitude is scepticism. It is to escape from this conclusion that some philosophers, accepting as a principle the impotency of reason, have emphasized the need of belief on the part of human nature, either asserting the primacy of belief over reason or else affirming a radical separation between reason and belief, that is, between science and philosophy on the one hand and religion on the other. Such is the position taken by Kant, when he distinguishes between pure reason, confined to subjectivity, and practical reason, which alone is able to put us by an act of faith in relation with objective reality. It is also a fideistic attitude which is the occasion of agnosticism, of positivism, of pragmatism and other modern forms of anti-intellectualism. As against these views, it must be noted that authority, even the authority of God, cannot be the supreme criterion of certitude, and an act of faith cannot be the primary form of human knowledge. This authority, indeed, in order to be a motive of assent, must be previously acknowledged as being certainly valid; before we believe in a proposition as revealed by God, we must first know with certitude that God exists, that He reveals such and such a proposition, and that His teaching is worthy of assent, all of which questions can and must be ultimately decided only by an act of intellectual assent based on objective evidence. Thus, fideism not only denies intellectual knowledge, but logically ruins faith itself.