Viewed subjectively, it is 'the certain and evident knowledge of the ultimate reasons or principles of truth attained by reasoning.'
Viewed objectively, it is 'the system of known truths belonging to the same order as a whole, and depending only upon one principle.'
This is founded on the definitions of Aristotle. In the sixth book of the Ethics, chapter iii. he says: 'From this it is evident what science is: to speak accurately, and not to follow mere similitudes; for we all understand that what we know cannot be otherwise than we know it. For whatsoever may or may not be, as a practical question, is not known to be, or not to be.'
Such also is the definition of St. Thomas. He says: 'Whatsoever truths are truly known as by certain knowledge (ut certa scientia) are known by resolution into their first principles, which of themselves are immediately present to the intellect … So that it is impossible that the same thing should be the object both of faith and of science, that is, because of the obscurity of the principles of faith.' He nevertheless calls theology a science. But Vasquez shows from Cajetan that this is to be understood not simply but relatively, non simpliciter, sed secundum quid. The Thomists generally hold theology to be a science; but imperfect in its kind.
Gregory of Valentia sums up the opinions of the Schools, and concludes as follows: 'That theology is not science is taught by Durandus, Ockam, Gabriel, and others, whose opinions I hold to be the truest.' He adds: 'Though it be not a proper science, it is a
