Chapter 4

THE ORDER BETWEEN THE INTRINSIC AND
THE EXTRINSIC PRINCIPLE OF CERTAINTY

1054. When I have a sure sign of the truth of a proposition (for example, an infallible authority affirming the proposition), I cannot doubt its certainty.
But the sign, in order to be effective, must first be certain itself. In this case, therefore, one certainty produces another certainty: I am certain of the proposition because I was first certain of the sign or reasoning that convinced me about the proposition. The extrinsic principle of the truth therefore is produced for me not by the certainty of the sign, but by a certainty presupposed by the sign.

But where does this sign obtain its certainty? If from another sure sign, we must ask where the certainty of that sign comes from. We obviously cannot continue the succession of signs to infinity: if I verify the first by the second, the second by the third, and so on to infinity, I must hold in mind an infinite succession of signs, which is absurd. Moreover, we would never discover the first sign on which all the others depend, and from which they draw their value. We must therefore end at a sign whose truth is known through itself, not through another sign. Thus, the extrinsic principle of certainty must be reduced to the higher, intrinsic principle of certainty. In this way, the ultimate principle of certainty is reduced to one only, that is, to truth, seen directly by the mind through intuition. Truth is self-evident, devoid of sign and without intervening arguments. (13)

Notes:

(13) We should note that the motive or reason impelling our assent must always be truth, because only truth could really persuade us that something is true. For example, if self-interest made me declare a proposition true, the proposition would not be certain; I would know that the reason moving my assent was utility, not truth. If a murderer threatens to stab me in the chest, unless I swear to some teaching, he is not persuading me; he is simply making me a perjurer. I know well enough that the threatened injury itself does not produce certainty because I know it as an injury, not truth, which has neither right nor power over my intellectual assent. Again, a person may be forced to assent to some teaching by suffering lengthy oppression or servitude, or by a continuous succession of sufferings accompanied by other means of persuasion (but never by the truth). Such treatment could produce a kind of persuasion, which however would not be certainty because it was produced by motives extraneous to the truth. A persuasion which had been initially caused by motives alien to the force of truth would become certainty only at the moment it was confirmed by truth coming into our spirit. The vision of truth, therefore, is the sole motive capable of producing certainty.