Chapter 3

THE TWO PRINCIPLES OF CERTAINTY

1050. We must distinguish two principles of certainty. One is a proposition which expresses the constituents of truth and could be called principium essendi [principle of being]. (7) The other, a proposition which expresses a sure sign of the truth, could be called principium cognoscendi [principle of knowing].

1051. It is clear that the principle which expresses the essence of truth must also be the principle of certainty. Whenever I can see the truth in what is presented to my mind, I need no other motive for being certain of the thing thought. In the same way, whenever I have a sure sign, according to which I must believe that what I think is true, I can reasonably and firmly believe what is presented to my thought, although I see neither its reason nor its truth.

1052. Let us see how these two principles relate to the three elements of certainty, that is, to truth in the object, firm persuasion in the subject, and a reason which produces the persuasion.
But we must first decide how to present our argument so that the discussion may proceed more clearly.
Anything whatsoever to which we give or withhold our assent can be expressed as a proposition. A proposition present to our spirit can also be said to be a cognition, in so far as we understand and know the proposition. I will therefore use the word `proposition' not to express any particular form of my mental conceptions but to express everything to which my persuasion is referred, even in the case of a simple idea. As I have said, even an idea can be changed into and expressed as a proposition. ( 8)

Granted this, I say that the assent or dissent I give to a proposition forms or removes persuasion in me. Assent must be motivated by a reason, if it is to produce a persuasion which gives certainty. Thus, a reason is the general cause of certainty; and the third of the three elements from which certainty results is that which generates certainty in the individual, the only real subject of certainty. (9)

1053. In order to assent to a proposition and so generate certainty in myself, I must therefore be moved by a reason; I must not assent at random or blindly.
A reason is necessary for one purpose only: to produce in me persuasion of the truth of the proposition. But if truth is intuitively manifest to me, the reason moving me is truth itself; I recognise truth, which presents itself to my spirit, and I experience it as the force generating in me an unmovable, reasonable persuasion. This persuasion is reasonable precisely because produced by the truth to which I alone have surrendered myself. Thus, the elements of my certainty are reduced to two: the truth in the object (which is also the reason for my persuasion), and the persuasion itself, caused by the truth in me, that is, in the subject.

But when I do not see the truth which is the supreme reason and evidence for the proposition, I must, in order to give a reasonable assent, have a motive, that is, some indication or sign by virtue of which I can reasonably believe that the truth is in the proposition (10) (even if I do not see it myself). This sure sign of the truth must be such that it cannot deceive me: it may be, for example, an infallible authority(11) in which I reasonably believe, although I may not understand what the authority is affirming. But again, generally speaking, any sure sign of the truth of a proposition can produce certainty in me, although the sign is extrinsic to the proposition and incapable of making me perceive and know (12) directly the truth contained in it.

These two principles of certainty, therefore, must be distinguished: we say one is `intrinsic' and the other `extrinsic' to the proposition. The first is directed not only to persuading and convincing us that truth must be present in the proposition, but is part of the proposition, showing us its truth clearly and making us intuit it with the eyes of our intellect. On the other hand, the second is not in the proposition, nor does it always relate to its contents. This principle, therefore, does not require us to understand.clearly the proposition. Whatever the proposition contains and in whatever way we understand it (even if stated in a foreign language or written in unintelligible characters), we prove to ourselves by means of the principle and become rationally convinced that the proposition MUST contain the truth. We must therefore give our full assent to its contents.

Notes:

(7) This careful distinction of the two principles of certainty gives me the advantage of avoiding many ambiguities in the course of the argument, and the reader the advantage of avoiding many misunderstandings. At the same time it shortens the discussion, which is always prolonged when uncertain and confused. We must also bear in mind that while certainty has a cause outside us, the properties of this cause, which have no relationship with certainty, must be excluded by the very nature of the present discussion.

(8) Every acquired idea presupposes a judgment. The first idea thus becomes a proposition if it is applied to itself by saying, for example, `Being is'.

(9) The subject of certainty is always an individual. Only an individual can give or withhold assent to a proposition, because only individuals really exist on this earth: humanity is purely an abstract idea. It would therefore be absurd to say (by changing an abstract into a real person, as the Abbé‚ de Lamennais does) that humanity, not individuals which compose humanity, assents and produces certainty. Moreover, to give assent is to pronounce a judgment. Hence, the proximate judge of certainty is without any doubt the individual, just as the proximate judge of moral actions is the conscience of each human being. This does not mean, however, that the individual need not follow a rule independent of himself in carrying out such a judgment.

(10) `Anyone who assents to what is uncertain is bound to err' (St. Augustine, Lib. 2, Contra Acad., c. 4).

(11) The authority is not the extrinsic principle of certainty considered in all its generality, but a particular principle subordinate to the general principle. Certain parts of arguments ab absurdo are subject to the same principle, that is, all those arguments in which the absurdity relates to the contents of the proposition materially understood. As a result, it would be absurd to suppose the proposition false, although its contents are either not known, or of no importance.

(12) St. Augustine thinks that the verb `to know' indicates better the intuition of truth, and `to believe' indicates better the assent given to a proposition on the faith of others or according to sense data: `Strictly speaking, we are said to know only that which we understand by a firm reason of our mind. But in normal speech we have no hesitation in saying that we know both what we perceive with our bodily senses and what we believe from witnesses worthy of our trust, ALTHOUGH WE UNDERSTAND THE GAP BETWEEN THESE TWO PROPOSITIONS AND THE FORMER PROPOSITION' (Retract., bk. 1, c. 14).