The Philosopher says (Metaph. vi, 4), "The true and the false reside not in things, but in the intellect."If our intellect conforms to reality, then one says this is truth. To find truth, then, we need to apply our intellects to understand everything; this is research. But if truth resides in the intellect, does not this imply a plurality of truths, one for each scientist's understanding of a thing? Does not this imply a relativism of truth? How can scientists, then, come to a consensus—not democratically by majority rule, however—about the truth of, say, a hydrogen atom? Here is this objection, viz., to the fact that the truth is in the intellect:
[T]ruth resides primarily in the intellect, and secondarily in things according as they are related to the intellect as their principle. Consequently there are various definitions of truth. Augustine says (De Vera Relig. xxxvi), "Truth is that whereby is made manifest that which is;" and Hilary says (De Trin. v) that "Truth makes being clear and evident" and this pertains to truth according as it is in the intellect. As to the truth of things in so far as they are related to the intellect, we have Augustine's definition (De Vera Relig. xxxvi), "Truth is a supreme likeness without any unlikeness to a principle": also Anselm's definition (De Verit. xii), "Truth is rightness, perceptible by the mind alone"; for that is right which is in accordance with the principle; also Avicenna's definition (Metaph. viii, 6), "The truth of each thing is a property of the essence which is immutably attached to it." The definition that "Truth is the equation of thought and thing" is applicable to it under either aspect.
[W]hatever is true, is true by reason of truth. If, then, truth is only in the intellect, nothing will be true except in so far as it is understood. But this is the error of the ancient philosophers, who said that whatever seems to be true is so. Consequently mutual contradictories seem to be true as seen by different persons at the same time.To which St. Thomas replies by invoking the divine intellect, the intellect of God who is Truth Itself (John 14:6):
The ancient philosophers held that the species of natural things did not proceed from any intellect, but were produced by chance. But as they saw that truth implies relation to intellect, they were compelled to base the truth of things on their relation to our intellect. From this, conclusions result that are inadmissible, and which the Philosopher refutes (Metaph. iv, 5ff.). Such, however, do not follow, if we say that the truth of things consists in their relation to the divine intellect.We can see that if "natural things did not proceed from any intellect, but were produced by chance" as the atheistic Darwinists think, then truth is only relative to each particular person's understanding of a natural thing. There would be no scientific consensus nor understanding. Science would be doomed. Yet there is hope.
As said above (Article 1), truth is found in the intellect according as it apprehends a thing as it is; and in things according as they have being conformable to an intellect. This is to the greatest degree found in God. For His being is not only conformed to His intellect, but it is the very act of His intellect; and His act of understanding is the measure and cause of every other being and of every other intellect, and He Himself is His own existence and act of understanding. Whence it follows not only that truth is in Him, but that He is truth itself, and the sovereign and first truth.Therefore, in order to avoid a cacophony of truths, we must "say that the truth of things consists in their relation to the divine intellect." This is why theology, the study of God, is the supreme science (ibid. Iª q. 1 a. 5 s. c.) with metaphysics and the other sciences being her handmaidens. So why does absolute truth no longer appear as the aim of modern universities and research institutions? The simple reasons are that most (1) deny the Ultimate Truth, God; (2) conceive academic freedom as an aimless free-inquiry; and (3) unquestioningly uphold as dogma the relativism of truth. "For to seek the truth [and understanding today] [...] [is] to follow flying game," as Aristotle says in Metaphysics IV, 5, 1009b40. It does not have to be this way.