Jacques Maritain Center : The First Principles of Knowledge

Chapter III.
Definition of Certitude and of the States of Mind Falling Short of Certitude.


  1. Definition of Certitude.
  2. The question at present is one rather of definition than of fact.
  3. Definitions of the states of mind which fall short of certitude.
    (a) Ignorance. (b) Doubt. (c) Suspicion. (d) Opinion.
  4. Probability, a very large subject, not here discussed at any length.
  5. The use of the word " belief."

1. THE assured possession of truth by the intellect is called Certitude, which is, therefore, defined to be the state of the mind when it firmly assents to something, because of motives which exclude at least all solid, reasonable misgivings, though not necessarily all misgivings whatsoever. The definition applies not only to every truth which is reached mediately by inference, but also to immediate intuitive truths, of which the motive lies simply in the self-evident connexion of the given terms. Hence it is not always needful to look for a motive outside of the judgment itself.

2. Such is a short description of what those competent to speak on the matter commonly understand by certitude. It is not yet formally under discussion whether we mortals can arrive at such a state; though that we can is implied in every pretence to rational discussion of any sort. Still as far as explicit declaration is concerned, just as in an earlier chapter it was enough to say hypothetically, that if we have knowledge, it will bear a resemblance to the thing known; so now it suffices to say, that if we have certitude, it must be as above defined. Positively, however, to allow that we may, perhaps, be devoid of all certitude in our knowledge and that we must wait for philosophy to settle the doubt, this would be to cut from under our feet all available ground for philosophizing. But we may omit the explicit assertion of a fact without allowing it to be dubious.

3. Certitude is far from being our only mental condition in regard to things; and it becomes of the highest importance, for a well-ordered mind, to distinguish its several attitudes in relation to objects of knowledge. Some confused intellects make no attempt to sort their own contents, to put like with like, and to mark off the unlike by contrast; neither have such minds any clear views as to what they know or what they do not know. It would help them vastly, as the beginning of a re-organization, to note the following stages in the ascent from ignorance to certainty.

(a) Ignorance strictly so called, is either purely negative, simple nescience, or else it is privative, -- want of some piece of knowledge which the person, all things considered, ought to possess. A surgeon need not know what the "eccentric" of a steam engine is, but he ought to know what a "tourniquet" is. Ignorance is not as bad as error; per accidens, it may even be "bliss;" but in itself at least it is no good, for it is nothing.

(b)Next to sheer ignorance comes doubt, which, in its widest sense, would include all the states intermediate between ignorance and certitude. But for technical purposes, or at any rate for the occasion, it is convenient to narrow down the meaning of the word by what in itself is rather an arbitrary limitation, and need not be borne in mind beyond the pages wherein the limitation is explained.

Mill{1} gives one definition of doubt which really belongs rather to sheer ignorance, when he describes doubt, "not as a state of consciousness, but the negation of a state of consciousness -- nothing positive, but simply the absence of belief." It is true the scholastics speak of a dubium negativum, but they make it more than mere ignorance; they apply the term to the state of the mind we are in, when a question is proposed, and the mind, simply for want of any valid reasons on either side, remains quite neutral. Thus if we are asked whether some large assembly forms an odd or an even number, we lean to neither side, for lack of the means of deciding, even with probability, one way rather than another.

Now if, just for convenience, a name may be given to the perfectly balanced state, it can be called negative doubt, and comes very near to sheer ignorance; but is not quite sheer ignorance because at least the question has been intelligently entertained, and its utter insolubility intelligently decided. It may be defined as the equipoise of the mind, due to the absence of any valid reasons on either side. The parallel definition of positive doubt is "the equipoise of the mind, due to the fact that the reasons on either side are equal and opposite." In one case the balance is due to the absence of producible reasons, in the other case to the presence of exactly countervailing reasons. Of course it would be absurd to insist on the constant use of the words, under these definitions, all the more so as no exact scales are usually at hand wherein to weigh reasons. Still the definitions are useful for the moment, while degrees between ignorance and certitude are being measured. Etymologically, according to Max Müller, dubium expresses literally the position between two points, and comes from duo, as Zweifel points back to zwei. The distinctions just drawn fit in well with the etymology.

(c) The first step out of doubt, when doubt is understood in the way above explained, may be called Suspicion, which is described as so faint an inclination to yield in one direction, that not even a probable assent is yielded, but there is a leaning towards a side.

(d) When, however, an assent is given, but as to a mere probability, and therefore only under restriction, there is Opinion, doxa, if not quite in the Platonic sense, then in the general sense of what, from the appearance, seems likeliest, or at all events likely. In opinion, so defined, there is evidently wide room for variation between the limits of slender and of very substantial probability. It is a matter of choice whether we say that the assent is given to the probability of the proposition, or to the proposition as probable. Cardinal Newman, because of his special use of the word "assent," prefers the former expression. Again, the admission must be made, that in ordinary speech it would be absurd to insist on the use of the words "doubt," "suspicion," and " opinion," in strict accordance with the account of them just given; and yet the account has its manifest utility. It puts before the mind successive stages on the way to certainty, and gives to each a name. Now plainly it belongs to logic not only to treat of certitude, but also to compare it with other states of mind, which form the constant surroundings of our group of assured convictions. Only the intelligences that are blessed with the absence of all uncertainty can afford to confine their attention to certainty alone.

4. Much might be said of probability, but this is hardly the place in which to say it. Under certain aspects its treatment is largely mathematical; and as, in many instances, the mathematicians guarantee their results only for an infinite series, it follows that for any practical series they do not guarantee them to be strictly accurate. They cannot lay down any definite limits, however large, with the certainty that this will secure a fair game of chance, ending in a balanced condition.{2} For the definite period, say one thousand years, spent in tossing heads and tails, may expire, just when a run of luck has fallen to one side. Still insurance companies, which, if no catastrophe happens, have a kind of interminable existence, can manage by statistics, not only to make their gains compensate their losses, but also give fair dividends to shareholders. For the information they require about the theory of chances, they look not to logicians, but to statisticians and mathematicians.

5. This chapter ought not to conclude without a remark on the use of the word "belief." To believe signifies sometimes (a) to hold a thing as a probable opinion; and sometimes (b) to hold it as certain, whether (a) generally, without specially distinguishing the nature of the grounds or (b) specially, on the ground of the testimony of witnesses, or (g) again specially, in cases where the object is not immediately presented to the perceptive faculties, e.g., belief in a fact as remembered.

What Hamilton{3} says of belief may be usefully quoted as a help to the understanding of subsequent discussions in which his opinions will be involved: "Knowledge and belief differ not only in degree, but in kind. Knowledge is a certainty founded upon insight: belief is a certainty founded upon feeling. The one is perspicuous and objective, the other obscure and subjective. Each, however, supposes the other, and an assurance is said to be a knowledge or a belief, according as one element or the other predominates." Elsewhere he says,{4} Belief is the primary condition of reason, and not reason the ultimate ground of belief." When further, Hamilton teaches, that we believe the Infinite, yet cannot conceive it, or know it as possible, he does not wish to retract his declaration that what we believe, we must always, to some extent, likewise know: but he falls certainly into an appearance of contradiction: and beyond apology his views are at times misty and misleading. Perhaps it was some participation in them which prompted. the line at the opening of In Memoriam:{5}:

Believing what we cannot know

The distinction is widely received, but probably not with very determinate meaning; sometimes it has its very legitimate sense of accepting, on sufficient authority, truths which we could not establish on their own intrinsic evidence, and which we do not fully comprehend after revelation.

With regard to the doubt which is often implied in the word "belief" it is, on religious principles, important to note, how the loss of dogmatic authority, and the assertion of private opinion, had much to do with spreading the erroneous notion that man's religious beliefs were but a set of opinions. Needless to say, in the Catholic Church, belief means absolute certainty on the supreme authority of God.


On the theory of probabilities, and as to the fact that the very improbable sometimes happens, the following extract is instructive: "An extraordinary incident in a game at whist occurred in the United Service Club, Calcutta, a few days ago. The players were Mr. Justice Norris, Dr. Harvey, Dr. Sanders, and Dr.Reeves. Two new packs were opened and were traded and shuffled in the usual way. Dr. Sanders had one of the packs cut to him, and proceeded to deal. He turned up the knave of clubs, and on sorting his hand found that he had the other twelve trumps. The fact was duly recorded in writing. The odds against the combination are 158,750,000,000 to one." -- St. James's Gazette, February 14, 1888.

{1} Examination of Sir W. Hamilton, c. ix. p. 133. (2nd Edit.)

{2} Cf. Note A at end of chapter.

{3} Metaphysics, Lecture iv. p. 62.

{4} Note A, on Reid, P. 760.

{5} "When I deny that the Infinite can by us be known, I am far from denying that by us it ought to be believed." (Metaphysis, Lecture ii. Appendix.) As to how we can believe the inconceivable, see Mansel, The Philosophy of the Conditioned, pp. 69, 70.

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