Jacques Maritain Center : The First Principles of Knowledge

The First Principles of Knowledge
Part I. The Nature of Certitude in General.

Chapter I.
Definition of Truth.


  1. Three kinds of truth.
  2. Definition of truth as found in knowledge. (a) The common-sense view, agreeing with the scholastic definition. (b) Assigned reasons for modifying and even radically altering that definition. (c) Assertion of the old definition, a course which the rest of this work must defend, but for which a little may be said at the outset.
  3. Definition of error, as a corollary to the definition of truth.


1. Truth is commonly divided into truth of things, truth of thought about things, and truth in the outward expression of our thought about things. The first kind of truth is called ontological, the third moral, and each of these is discussed in separate volumes of the present series. It is with the second member of this division, about what is often styled logical truth, that the treatise which we are here beginning is concerned. What true knowledge is, and how its possession by the human intellect can be vindicated, these are the questions specially calling for our investigation.

2. (a) An ordinary man, if asked to explain what true knowledge is, would reply simply, that knowledge was true when the thing was really such as we thought it to be. He would thus agree with the definition of the schoolmen, "Truth is an equation or a conformity of thought to thing." {1}

(b) But a matter which, at first sight, seems thus readily settled, presents, on reflexion, a number of difficulties, which some have regarded as so serious as to upset the plain man's view, backed though it be, by other philosophies, and by the massive volumes of scholastic philosophy which the centuries have piled one on the top of another. For when the case is more narrowly sifted, are we not driven to make some awkward inquiries: How can mental images be like outer objects, especially material objects? How are sensations like the external bodies which stimulate them? When several senses give their reports of one object, as there is no likeness between the several reports, say between the taste of an orange and its colour, how can they be all like the object? What is the conclusion from the notorious fact that in different persons, and even in the same person at different times, any one of the five senses may bear divergent testimonies? Besides, even if our knowledge were like what we call its object, to observe this correspondence must be an act of comparison, which not we, but some one else, must make: for we at least cannot compare the thing as known to us, with the thing as out of our knowledge. Such an attempt on our part would be preposterous, a fraudulent endeavour to assert, for our essentially relative faculties, an absolute validity.

Moved by these considerations, a number of modern philosophers dare to claim for human knowledge only some correspondence with its object which is less than that of likeness, and is describable as symbolic: just as a mathematical formula, though not like, may yet symbolize, the path of a cannon-ball. Thus, in the words of Mr. Frederick Harrison, "our scientific conceptions have a very good working correspondence with the assumed reality without; but we have no means of knowing whether the absolute correspondence between them be great or small, or whether there be any absolute correspondence at all." Mr. H. Spencer,{2} in expounding his theory of "transfigured realism," sets forth still more clearly the position of the "relativist," that is, of the philosopher who denies that we can know things absolutely as they are. Maintaining that "resistance, as disclosed by opposition to our energies, is the only species of external activity which we are obliged to think of as subjectively and objectively the same," still even here he will not positively affirm that knowledge is like the object. And for ordinary objects his teaching is this: "If x and y are the two uniformly connected properties in some outer object, while a and b are the effects which they produce in our consciousness; the sole need is that a and b, and the relation between them, shall always answer to x and y, and the relation between them. It matters not if a and b are both like x and y, or not; could they be exactly identical with them we should not be one whit the better, and their total dissimilarity is no disadvantage."{3} In other words, if for every definite change in objects, there is one constant change in the mind which is affected by that object, then this is enough, without any resemblance of thought to thing; concomitant variation suffices.

(c) Against this theory the time-honoured definition of knowledge must be re-affirmed. The objections raised against it are only the old arguments in favour of complete distrust in the power of man to attain truth; and to refute them will be the main purpose of all that follows in this volume. At the outset, this book defines truth of intellect to be "the conformity of thought to thing": subsequently its one grand aim will be gradually to make good the definition. Whilst patiently awaiting the development of a long line of argument, the reader may find some consolation in a few declarations that can be offered him at once. First of all, when knowledge is said to be a sort of "equation" of mind to thing, it is not meant that knowledge, in order to be true, must exhaust the whole object: a partial knowledge is true, as far as it goes, especially when it is recognized as only partial.

Next, the likeness which is asserted is quite sui generis. An idea, -- to use the word at present in its broad sense of any act of knowledge, -- is not a dead picture, but something effected by and in the living, cognitive mind; it is a thing with a conscious meaning of its own:{4} it is, as Spinoza says, self-assertive or self-referent; it is what the schoolmen sometimes call a signum a quo, a sign which taken, not in its isolation as a mere phenomenon, but as it exists in the mind, is the knowledge of the thing signified. Thus it differs from a signum ex quo, a sign which has first to be known, that from it the mind may travel to the thing signified. To quote Father Liberatore: "The signum a quo is that which, by being first known, leads on the mind to the knowledge of the thing it signifies. Another way of signifying is presented to us in those inward signs which do not come before the mind as objects of its perceptions, but which, by informing the cognitive faculty, effect actual knowledge. These latter may be called signa in quibus [or, signa quibus], or also, 'formal signs,' in that they do not represent objects as previously known, but are forms determining the mind to perceive the object. To this category belong mental concepts."{5} Hence the representative, significative, or meaning power of an idea is not photographic, nor anything analogous to photography; and to fancy it so is the cardinal error of scepticism. The idea depicts its object in no way open to our artists: neither by similarity of substance, nor of colour, nor of outline, nor by any mode of material portraiture. The process is so peculiarly mental or spiritual, that illustrations borrowed from matter are more calculated to mislead than to direct. The uniqueness of the phenomenon is essentially its strangeness, for we cannot explain it by reduction to any familiar class. Yet the strangeness is welcome as serving, in another treatise, to show the inadequacy of the materialistic hypothesis.

A difficulty, raised by Cousin, really amounts to no more than a matter of words. He says{6} that an idea cannot be "an image" of an object, because only material representations can be "images;" that we cannot strictly speak of "likeness" between spiritual objects, but only between material: and that therefore, if we do call ideas "images" bearing the "likeness" of their objects, we are talking not properly but metaphorically. As our knowledge begins in sense, so far all our spiritual ideas may be said to be conveyed in metaphorical terms; it seems however a fair procedure to regard a term as no longer metaphorical, when we no longer advert to the figurative meaning, but pass straight to the main object. Thus, in speaking of moral rectitude we hardly refer to the image of a man keeping the straight path as he walks; but we go at once to the notion of right conduct. Similarly, whatever may have been the origin of the terms, we can now claim to apply the word "image" or "likeness" straight to spiritual resemblances. However, if any one should insist on seeing a trace of metaphor left here, the point is not worth controverting.

We assume, therefore, that ideas are, in the language of Aristotle, homoiômata tôn pragmatôn -- "likenesses of things," and so stand contrasted with words which are conventional signs: whereby a special meaning is given to the saying, that man is a microcosm.{7} Not only does man sum up the several constituents of our Cosmos by uniting together mineral, vegetable, and animal nature; but by knowing all things, he, in a manner, reproduces, or becomes all things. Homo est quod est, says the materialist scoffingly; translating the words, "Man is what he eats, what his food makes him." False as a complete statement, this is true as a partial statement; and equally true is it, homo est quod scit -- Man is what he knows." In this sense St. Thomas writes {anima est quomodo omniaThe soul is in some sense everything;" which is the repetition of Aristotle,{8} he psuchê ta onta pôs esti panta -- "The soul is in a manner all things."

3. From the definition of true knowledge before given, a corollary as to the nature of error may be gathered. Not any absence of likeness between thought and thing is straightway falsehood: rather such mere absence is ignorance. Before downright error is reached, there must be not only want of conformity but positive deformity. For knowledge, however limited, is true knowledge so long as it does not transgress or deny its own limits -- a fact highly important to finite intelligences like ourselves who can but "know in part." Be it our consolation, then, to remember that the opposition between knowledge and ignorance is only what the logicians call a "contradictory; " while it is not till we have gone as far as the "contrary" opposition that we commit error.


(i) The mysteriousness of the act of knowledge, and its apparent impossibility on any material analogy, were points that arrested the attention of the early speculators. Whereas St. Thomas {a} argued that because the mind was capable of becoming cognizant of bodies it could not itself be corporeal, some of the old Greeks had pushed to its extremes the principle, Like is known by like -- homoia homoiois gignôsketei. Empedocles, for example, had said, "We perceive earth by means of earth, water by means of water, air by means of air, fire by means of fire, love by means of love, and strife by means of strife," where love and strife stand for what we call attractive and repulsive forces. Others spoke either of the eye sending out its influences to the object, or of the object emitting its eidôla, or minute images to the eye, which,

All such conceptions are the follies of a crude materialism; and a long way the better course is, while admitting that how knowledge is possible is inscrutable to us, yet to insist that the fact is manifest to experience. The reaction of our faculties to their appropriate stimuli must simply be accepted for what it -- declares itself to be, namely, not any kind of a reaction, but the special reaction which must be called cognitive.

(2) Preferring theory to fact, and a theory the very arguments for which rest on an assumption which is just the contrary to what they are fancied to prove, a number of modern writers quite set aside the doctrine that we have knowledge like to the realities outside of ourselves. From America comes the voice of Mr. Borden Browne, telling us, as an introduction to his volume on Metaphysics, that because we cannot compare thought with being, therefore, "truth cannot be viewed as the, correspondence of thought and thing, but as the universally valid in our thought of the thing. That is the true conception of reality, which grasps the common to all, and not the special to one;" so that the test of truth is "the necessity of the conception and the inner harmony between several conceptions. It is not the lack of harmony between our conceptions and reality which disturbs, but the discord of our conceptions among themselves." A like utterance we have from a German author, according to whom "truth does not consist in any sort of correspondence between our thought and the things outside us, but in a character that belongs to our mode of putting together our internal experiences. Our thoughts are true, when their nature, as internal events, is understood; when they are placed in equal relation to the rest of experience. The criterion of truth is the feeling of universality and necessity in the ultimate axioms." In our own country we have some authors completely rejecting the doctrine that truth is conformity of mind to thing; while others, using the same words, are less thorough in their divergence from us, though sufficiently divergent to be in decided opposition. They distinguish between perception and thought, so as to make thought more especially a matter of subjective forms without ascertainable objective validity. "Truth relatively to the human mind," writes Mansel,{c} "cannot be defined as a conformity with its object; for to us the object exists only as it is known by one or other faculty. Hence material truth consists rather in the conformity of the object as represented in thought with the object as presented in intuition; while logical truth consists in the conformity of thought to its own laws." With these words may be compared the following from another countryman of ours, Mr. S. Hodgson: "Without thought no truth, without perception no reality. By reality I understand the actual existence of the object, its actual presence to consciousness.{d} Reality is not greater after thought than before; thought has, transformed it into a new shape, has given it new relations, but has added nothing to its real existence. Truth, on the other hand, is a product of thought, the form which an object assumes after investigation, and is thus greater after thought than before it. Reality depends on the relation between objects and consciousness: truth on the relation between objects in consciousness." The difference here is partly a matter of words, but it is also a matter of fundamental doctrine; and with regard to each of the authors, cited, it is sufficient for present purposes if the reader understands them as representatives of a now widespread revolt against the scholastic definition, "All truth in cognition consists of the assimilation or conformity of the mind with the object."{e}

(3) The consequences of the doctrine logically carried out, that ideas are mere symbols, are very fatal to all religious belief, as well as to everything worth calling true knowledge: and though it is often protested, that a doctrine is not to be judged by its inconvenient logical consequences, but by its intrinsic truth, yet there are consequences so manifestly bad, as to afford evidence that the premisses, whence they are drawn, cannot be sound. If our knowledge of things is what adversaries say it is, then it is not genuine knowledge at all: and this some of themselves admit. Take, for instance, Lange's confession, in words gathered from a long declaration: "All our knowledge of nature is, in fact, no knowledge at all, and affords us merely the substitute for an explanation. The intelligible world is. a world of poesy, and precisely upon this fact rests its worth and nobility. No thought is so calculated to reconcile poesy and science as the thought, that all our reality is only appearance."{f} So, too, Mr. Spencer{g} is perpetually harping on the string, "ultimate religious ideas, and ultimate scientific ideas are mere symbols of the actual, not cognitions;" even "the personality of which each is conscious, and of which the existence is to each a fact beyond all others the most certain, cannot be truly known at all: knowledge of it is forbidden by the very nature of thought." It is well that the reader should thus be brought plainly to see into what a gulf of nescience he is about to plunge, if he is resolved to take up the theory, that the old definition of man's actual knowledge must be abandoned. Ultimately he must be driven to say with Fichte, {h} "Reality all merges into a marvellous dream, without life to dream about or spirit to dream -- a dream which is gathered up into a dream of itself."

(4) In unconscious anticipation of modern difficulties, the scholastics strongly insisted on knowledge as being mental assimilation; in proof of which assertion we will borrow a few citations made by Kleutgen on this subject.{i} "Every cognition is brought about by the likeness of the object known, in the mind that knows."{j} "In the first place, we suppose it to be essential to the act of the intellect, aye, and to every cognition, that a certain assimilation be produced in the mind of the intelligent agent. This fundamental position may be taken to be a dogma and a principle both in theology and in philosophy, questioned by none."{k} It can in no wise be denied, that when the rational mind, reflecting on itself, becomes self-conscious, a likeness of itself is produced by this cognition, or even that this cognition is an image of self, fashioned after its own likeness, as it were an impression of self upon self."{l} Theologically the doctrine is of importance in reference to the Blessed Trinity, in, which the Son is begotten in the likeness of the Father, as the Father's Word, or intelligible term.{m} Silvester Maurus has some apposite remarks: "The procession of the Son is of such sort as to express the Father in His nature and essence. The act of the intellect, whereby we know ourselves, is likewise posited for the purpose of expressing the intelligent agent in his essence and nature, into which the intellect alone can penetrate. Since in God, the Word, i.e., the term produced by the act of the intellect, receives the self-same nature and essence with the Father, His production or procession is hence fitly termed a generation, that is, the origin of a living subject from a conjoint living principle, from whom it receives a similar nature."{n}

{1} Tongiorgi, Institutiones Philosophicae, Vol. I, nn. 370, seq.

{2} Mr. Spencer's doctrine may be seen in his Psychology, Part I. c. xix.; First Principles, Part I, c. ii.

{3} First Principles, Part I. c. iv. S. 25.

{4} Hence Hume greatly errs: "The reference of an idea to an object is an extraneous denomination; of which in itself it bears no mark or character." (Treatise, Part I., sec. Vii. Pp. 327, 330)

{5} "Signum ex quo quod prius in se cognoscatur et ex sui cognitione potentiam ducat in cognitionem rei significatae. Alter modus significandi locum habet in signis internis, quae non se offerunt ut objecta sed informando potentiam eam efficiunt cognoscentem in actu. Haec dici possunt signa in quibus [vel signa quibus], vel etiam signa formalia: quia non repraesentant tanquam objecta prius cognita sed tanquam formae determinantes potentiam ad perceptionem objecti. Hujusmodi est conceptus mentis." (Logica, Pars I. c. I. n. 5.)

{6} Histoire de la Philosophie, lecon 2ime, et alibi passim.

{7} Silvester Maurus, Quaestiones Philosophicae, quaestio vi.

{8} De Anima, Lib. III. c. viii. 2.

{a} Ia, q. 75, art. 2.

{b} Quae quasi membranae, summo de corpore rertim
Dereptae. volitant ultroque citroque per auras.
-- (Lucretius. iv. 31, 32.

{c} Prolegmena Logica, c. vi. in fine; also Mansel's Aldrich, Appendix M. p. 277. (3rd Ed.)

{d} See Green on Thought as constitutive of the Reality of World Introduction to Hume, §173. The passage from Mr. Hodgson is found in his book on Time and Space,p. 352

{e} "Veritas in cognoscendo est mentis assimilatio vel conformitas ad rem."

{f} History of Materialism (English Translation), Vol. II. p. 309.

{g} See the conclusions to the early part of First Principles, Part I. cc. iv. and v., Part II. c. iii.

{h} Quoted in Hamilton's Reid, p. 129, note.

{i} Die Philosophie der Vorzeit, I. i. §§23-25.

{j} "Omnis cognitio fit secundum similitudinem cogniti in cognoscente." (St. Thomas, Contra Gentes, Lib. ii. c. 77.)

{k} "In primis supponimus de ratione intellectionis, imo et cognitionis esse, ut per quamdam assimilationem intra mentem intelligentis fiat. Hoc fundamentum videtur esse veluti dogma, et principium in philosophia et theologia communi consensu receptum. (Suarez, De Angelis,Lib. ii. c. 3; De Anima, Lib. iii. c. i.)

{l} "Nulla ratione negari potest, cum mens rationalis se ipsam cogitando intelligit, imaginem ipsius nasci in sua cognitione; imo ipsam cognitionem sui esse suam imaginem ad sui similitudinem, tanquam ex ejus impressione formatam." (St. Anselm, Monol., c. 33.)

{m} Heb. i. 3; Coloss. i. 15.

{n} "Filius producitur ad hunc finem ut exprimat patrem in natura et essentia. Intellectio, qua quis intelligit seipsum, producitur in hunc finem ut exprimat intelligentem in natura et essentia, quam penetrat solus intellectus. In divinis intellectio, producta, seu Verbum, accipit eandem numero naturam et essentiam Patris: ergo ejus productio proprie est generatio hoc est, origo viventis a vivente principio conjuncto, in similitudinem naturae." Quaestiones Philosophicae, q. ii)

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