Both in ordinary life and in philosophical discussions the term reason is of frequent occurrence in different significations.
Etymologically the word comes to us, through the French, from the Latin ratio, which is originally the functional noun of the verb reor, "I think" (i.e. I propose a res to my mind). According to Donaldson, res=h-ra-is, a derivative from hir=cheír (hand); hence res is "that which is handled", and means an object of thought, in accordance with that practical tendency of the Roman mind which treated all realities as palpable. Ratio, in opposition to res, denotes the mode or act of thinking; by extension it comes to designate on the one hand the faculty of thinking and on the other the formal element of thought, such as plan, account, ground, etc. This wide use of the word reason to denote the cognitive faculty (especially when dealing with intrinsic evidence, as opposed to authority) is still the commonest. The word has been used in this sense in a definition of the Vatican Council (Denzinger, "Enchiridion", 11th ed., Freiburg, 1911, nn. 1785-6); but already in Aristotle we have a clear distinction between intellect (voûs), as the intuitive faculty, and reason (lógos), as the discursive or inferential faculty. This distinction was maintained by the Schoolmen. Yet since Kant, the word reason has been used to shelter a bewildering chaos of notions. Besides using reason (Vernunft) as distinguished from the faculties of conception (Verstand) and Judgment (Urteilskraft), Kant employed the word in a transcendental sense as the function of subsuming under the unity of the ideas the concepts and rules of the understanding. Subsequent German philosophers, as Schopenhauer complained, "tried, with shameless audacity, to smuggle in under this name an entirely spurious faculty of immediate, metaphysical so-called super-sensuous knowledge".
In its general sense, therefore, reason may be attributed to God, and an angel may be called rational. But in its narrower meaning reason is man's differentia, at once his necessity and his privilege; that by which he is "a little less than the angels", and that by which he excels the brutes. Reasoning, as St. Thomas says, is a defect of intellect. True, in certain acts our mind functions as intellect; there are immediate truths (ámesa) and first principles (archaí) which we intuit or grasp with our intellect; and in such verities there can be no deception or error. On this point the Scholastic system may be said to be absolutely intellectualist or noocentric. The meanest intellect is, to use an expression of St. Augustine, capax Dei. Within a certain region our cognitive faculties are absolutely infallible. Yet the Scholastics also unanimously hold that man's specific mark is ratiocination or discursus. Some indeed, like St. Augustine (who was intent on his analogy between logos in man and in the Blessed Trinity), insist on the intuitional aspect of our mental operations, and pass over the actual process as a whole. Yet none denied that in this life our knowledge is a thing of shreds and patches, laboriously woven from the threads of sense. It is only in patria, for instance, that God's existence will be to us as self-evident as the principle of contradiction is now. The beatific vision will, in fact, be not only as evident, but also as immediate as our present intuition of personal consciousness. But then we shall be on a level with the angels, who are subsistent intelligences or pure intuitives. An angel, in Scholastic philosophy, is practically the equivalent of noûs (intellectus, intellegentia) when used by such writers as Aristotle, Porphyry, Plotinus, or Pseudo-Dionysius, to denote not a faculty, but a species of being.
Opposed to this ideal intellection, so characteristic of Scholastic angelology, is our actual human experience, which is a gignómenon, a coming to be. Man is rational in the sense that he is a being who arrives at conclusions from premises. Our intellectual life is a process, a voyage of discovery; our knowledge is not a static ready-made whole; it is rather an organism instinct with life and growth. Each new conclusion becomes the basis of further inference. Hence, too, the word reason is used to signify a premise or ground of knowledge, as distinguished from a cause or real ground. So important is this distinction that one may say herein lies the nucleus of all philosophy. The task of the philosopher is to distinguish the a priori of logic form from the a priori of time; and that this task is a difficult one is testified by the existence of the many systems of psychologism and evolutionism. Reasoning, therefore, must be asserted to be a process sui generis. This is perhaps the best answer to give to the question, so much discussed by the old logicians, as to what kind of causative influence the premises exert on the conclusion. We can only say, they validate it, they are its warrant. For inference is not a mere succession in time; it is a nexus thought-of, not merely an association between thoughts. An irrational conclusion or a misleading association is as much a fact and a result as a correct conclusion; the existence of the latter is explained only by its logical parentage. Hence the futility of trying to account completely for the existence of a human thought--the conclusion of a train of reasoning--simply by the accompanying sense-data and psychological associations. The question of validity is prior to all problems of genesis; for rational knowledge can never be the product of irrational conditions.
Allowing then the indefinability of ratiocination, we may proceed to ask if inference is homogeneous; in other words, are there different forms of reasoning? This raises the difficult question as to whether deduction and induction are ultimately irreducible modes of reasoning. The issue is usually confused by a very narrow definition of the syllogism, which has to be fitted into the word-grooves prescribed by syntax. But if, developing Aristotle's thought, we regard a syllogism as the unit of reasoning, then we may define it as the inference of a relation between A and C from a relation of A to B compounded with a relation of B to C. As an illustration we might instance Mill's famous example of the village matron's inference. Mill calls it reasoning from particulars by analogy; but it can easily be seen to be a syllogism; this drug (A) cured my Lucy (B), who had the same sickness as this neighbour's child (C), and hence will cure this child (C). All reasoning seems to consist in such unit steps, and it seems misleading to talk of inference vi materiæ material and formal are relative terms.
There is an important sense, however, in which the epithet "material" has been applied to reasoning, to denote illation in which the relational formality has not yet been dissected out. The same laws of thought rule the philosopher's reasoning and the peasant's, but the latter's conclusion will only be fairly certain when its matter comes within his usual cognizance. A man can reason well about familiar matter; but, unless he has explicitly examined the illative process, he will hesitate and err when dealing with new subject-matter. The mistakes of inventors like Newton and Leibniz are very instructive on this point. We are all, then, as Newman put it, more or less departmental; we reason with unequal facility on different subjects. Does it follow that in such cases of concrete informal reasoning there is a rational surplusage of assurance over evidence? This does not seem so clear, and cannot be answered without some analysis. Long before the dawn of modern psychology, Aristotle emphasized the fact that we never think without having an accompanying sense-process, whether it be a visual image, or an auditory symbol or even the motor impression of a word. The Scholastics also admitted this, and indeed many urged the necessity of this conversio ad phantasmata as the explanation of our piecemeal ratiocinative mode of learning. But this is not equivalent to saying that all reasoning can be exactly formulated, crystallized, as it were, into words. Language, after all, is merely a conventional drapery of our thought, which is convenient for logical analysis and for communicating with others. But do we not in ordinary life often syllogize in sights and reason in sounds? Does not our mind in its inferences leap far ahead of the sluggish machinery of language? And which of us has ever succeeded in fully analyzing his most commonplace attitude or emotion? To account, then, for the major part of our existence we must admit something analogous to the Aristotelean phrónesis) whether we call it the illative sense, or the artistic reason, or implicit thought. The main thing to observe is that it is not a special faculty. It is our reason acting under disabilities of language rather than of thought; for, after all, evidence is for ourselves while demonstration has reference to the audience.
These experiences have, however, been interpreted in an anti-intellectualist sense. The Pragmatist school regards reasoning as completely determined by its relevance to purpose or interest. And, again, many philosophers (Kant, the Modernists, and many Protestant theologians under the influence of Schleiermacher) have exaggerated the dualism between head and heart. In fact, a species of epistemological mysticism has been devised (cf. Gefüsqlaube, raisons du coeur, etc.). So far as this bears on the problem of reason, we may briefly state the case. It is true that our reason works purposively--that is, reason is selective of our subject-matter, but it is not creative or transforming. Nature is an ordered cosmos of which we form a part, so that every object in it has a "practical" bearing on our lives, is connected with our rational, sensitive, or natural appetency. The known is never completely out of resonance with our volitions and emotions. To affirm anything, or to reason about a subject, is at once to take up a position before it. This is especially true of moral and religious matter, and indeed the emotional genesis of ethical convictions has often been urged as a proof of their irrationality. But we should not forget that the liability to be influenced by emotional causes is not confined to ethical or religious reasoning. To put the case generally, we may ask: What precisely is meant by regarding feeling (or will) as forming with reason a co-ordinate source of knowledge? (Cf. G.E. Moore "Principia Ethica", sec. 79-80.) It may be meant that to have a certain feeling towards a conclusion is the same as to have reasoned it; and this is true in the sense that the complex "feeling" may include ratiocination. But when I draw a conclusion, I do not mean that I prefer it or am affected by it. And the fact that the two things can be distinguished is fatal to the assumed co-ordination between emotion and reason. As St. Thomas urged against the pseudo-mystics and Augustinians of all ages, volition is possible only in so far as it includes cognition; and, we may add, emotion is a mode of experience, only inasmuch as it presupposes knowledge.
Again, it may be meant that, without certain experiences of feeling and willing we should not be able to draw certain ethical conclusions. This may be admitted as a psychological fact, viz. that there are many exercises of reason which we shall not correctly perform without an ethical habituation (ethismiô tini, as Aristotle says). In this connection it is interesting to note that Cardinal Newman's object in writing the "Grammar of Assent" was "to show that a right moral state of mind germinates or even generates good intellectual principles". This is very far from countenancing the Kantian view of the practical reason. The School admits a practical reason or "synteresis" (Gewissen, psychological conscience), in the sense of a natural habit of moral Principles. But St. Thomas strenuously denies that it is specialis potentia ratione altior (a special faculty higher than reason).
Finally, a word may be added on the so-called reason of animals. Man is called animal rationale; this expression stands for what Aristotle might call zôon logistikón. The word zôov (in German, Lebewesen), which Aristotle applied even to God, does not mean "animal", but "living being". Is there then, any rational animal? Catholic philosophy attributes to animals a faculty (vis æstimativa) whose function, analogous to that of reason, might, for want of a better name, be called "estimation". Such a faculty also exists in man, but in a higher form, and was called by the Scholastics ratio particularis or vis cogitativa. Unless animals had this organic faculty, it is hard to see how they could apprehend those pragmatic relations (intentioned) such as utility, danger, etc., which are not objects of external sense. To this extent we may allow that the psychic life of brute animals is one of "meanings" and "values". In some way they apprehend aspects and relations. Otherwise such complex co-ordinations as those required for nest-architecture and food-quest would be inconceivable. The extreme views of Bethe, Uexküll, and others almost imply a return to Cartesian Mechanicism, and really refute themselves. The danger lies rather in the anthropomorphic exaggeration of the powers of the animal mind. Experience has shown how fatally easy it is to read human feelings and reasonings into the "mind" of one's favourite cat or pet lapdog. Continuous, patient observations, like those of Mrs. Mary Austin on sheep or of Professor Yerkes on the dancing-mouse, are worth any number of isolated anecdotes. It may be surely affirmed that there is not a single unambiguous record of animal ratiocination. Such experiments as those of Thorndike (on hungry cats shut up in a cage and forced to learn the way out to food) are easily explained by the gradual stereotyping of association between visual impression and motor response, to the exclusion of other random associations. That animals are incapable of rational valuation is confirmed by the recent observations of Forel, Plateau, and others, who have shown that bees (and probably all insects) have no memory of facts, but only of time and distance. Reason, therefore, is still the exclusive prerogative of man. (See DEDUCTION; INDUCTION; INSTINCT; INTELLECT; INTUITION; KNOWLEDGE.)
APA citation. (1911). Reason. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved April 26, 2010 from New Advent: http://www.newadvent.org/cathen/12673b.htm
MLA citation. "Reason." The Catholic Encyclopedia. Vol. 12. New York: Robert Appleton Company, 1911. 26 Apr. 2010 <http://www.newadvent.org/cathen/12673b.htm>.
Transcription. This article was transcribed for New Advent by Rick McCarty.
Ecclesiastical approbation. Nihil Obstat. June 1, 1911. Remy Lafort, S.T.D., Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York.
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