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 SCEPTICISM

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SCEPTICISM

of Scepticism succeeded. But Aristotle did more than this. He propounded the doctrine of intuition or self-evident truth. All things cannot be proved, he said; yet an infinite regress is impossible. Hence there must be somewhere self-evident principles, which are no mere assumptions, but which underlie the structure of human knowledge and are presup- posed by the very nature of things (Metaph., 1005 b, 1006 a). This doctrine, later on, was to prove one of the chief forces that checked the destructive on- slaught of the Sceptics ; for, even if Aristotle's dictum cannot be proved, it none the less states a fact which to many is itself .self-evident. It was the Stoics who first took "evidence" as the ultimate criterion of truth. Perceptions, they taught, are valid when they are characterized by ivapyeia, i. e. when their objects are manifest, clear, or obvious. Similarly conceptions and judgments are valid when we are conscious that in them there is KaTd\r}\pis an apprehension of reality. Contemporaneously, how- ever, with Zeno, the founder of Stocism, lived Pyrrho the Sceptic (d. about 270 b. c), who, though he ad- mitted that we can know "appearance", denied that we can know anything of the reality that underlies it. Ou5^v fxaWov — nothing is more one thing than another. Contradictory statements, therefore, may both be true. A scepticism so radical as this, the Stoics argued, is useless for practical life; and this argument bore fruit, .\rcesilaus, founder of the Mid- dle Academy (third century b. c), though rejecting the Stoic criterion and affirming that nothing could be known for certain, nevertheless admitted that some criterion is needed whereby to direct our actions in practice, and with this in view suggested that we should assent to what is reasonable (rd eiXoyof). For "the reasonable" Carneades, who founded the Third Academy (second century b. c), substituted "the probable": propositions which after careful examination manifest no contradiction, external or internal, are iriOavr] (probable) Kal dirfpiaTaros (secure) Kal irepi5evn4vri (thoroughly tested) (Sextus Empiricus "Adv. Math.", VII, 166). A sub.sequent attempt to reconcile conflicting doctrines having proved futile, however, the Academy lapsed into Pyrrhonism, .^nesidemus sums up the traditional arguments of the Sceptics under ten heads, which later on (second century a. d.) were reduced by Sextus Empiricus to five: (1) human judgments and human theories are contradictory; (2) all proof involves an infinite re- gress; (3) perceptual data are relative both to the percipient and to one another; (4) axioms, or self- evident truths, are really assumptions; (5) all syllogistic reasoning involves a didWrjXos (a vicious circle), for the major premise can be proved only by complete induction, and the possibility of complete induction supposes the truth of the conclusion (Sextus Emp., "Hyp. Pyrrh.", I, 164; II, 134; Diogenes Laertius, IX, 88).

From Scepticism the neo-Platonists sought refuge in the immediacy of a mystic experience; Augustus and Anselm in faith which in supernatural matters must precede both experience and knowledge (cf. Augustine, "De vera relig.", xxiv, xxv; De util. cred.", ix; Anselm, "De fid. Trin.", ii); St. Thomas and the Scholastics in a rational, coherent, and sys- tematic theory of the ultimate nature of things, based on self-evident truths but consistent also with the facts of experience, and consistent too with the tnith of revelation, which thus serves to confirm what we have already discovered by the light of natural reason. But with the Renaissance, characterized as it was by an indiscriminate enthusiasm for all forms of Greek thought, it was only natural that the Scepticism of the Greeks should be revived. In this movement Mon- taigne (d. 1592), Charron (d. 1603), Sanchez (d. 1632), Pascal (d. 1662), Sorbicre (d. 1670), Le Vayer (d. 1672), Hirnhaym (d. 1679), Foucher (d. 1696), Bayle

(d. 1706), Huet (d. 1721), all took part. Its aim was to discredit reason on the old grounds of contradiction and of the impos.sibility of proving anything. Huet, Bishop of Avranches, and others sought to argue from the bankruptcy of reason to the necessity and suffi- ciency of faith. But for the most part, faith, under- stood in the Catholic sense of belief in a system of re- vealed doctrines capable of intelligent expression and rational interpretation, so far from being exempt from the attacks of the Sceptics, was rather (as it still is) the chief object against which their efforts were directed. Faith, as they understood it, was blind and unreason- ing. The diversity of doctrine introduced by Pro- testantism had rendered all other faith, in their view, no less contradictory than philosophy and natural belief.

In Hume Scepticism finds a new argument derived from the psychology of Locke. A critical examina- tion of human cognition, it was said, reveals the fact that the data of knowledge consist merely of impres- sions — distinct, successive, discreet. These the mind connects in various ways, and these ways of connect- ing things become habitual. Thus the principle of causality, the propositions of arithmetic, geometry, and algebra, physical laws, etc., in short all forms of synthesis and relation, are subjective in origin. They have no objective validity, and their alleged "neces- sity" is but a psvchological feeling arising from the force of habit. We undoubtedly believe in real thmgs and real causes; but this is merely because we have grown accustomed so to group and connect our mental impre.s.sions. The arguments of Pyrrho and other Sceptics are unanswerable, their Scepticism reasonable and well-founded; but in practical life it is too much trouble to think otherwise than we do think, and we could not get on if we did. Kant's answer to Hume was embodied in a philosophy as eminently subjec- tive as that of Hume himself. Consequently it failed, and resulted only in further Scepticism, implicit, if not actually professed. And nowadays physical science, which in Kant's time alone held its own against the inroads of Scepticism, is as thoroughly per- meated with it as the rest of our beliefs. One in- stance must sufficc^-that of Mr. A. J. Balfour, who in his "Defence of Philosophic Doubt" seeks to uphold religious belief on the equivocal ground that it is no less certain than scientific theory and method. There is, he says, (1) no satisfactory means of mf er- ring the general from the particular (c. ii), (2) no empirical proof of the law of causaUty (c. iii), (3) no adequate guarantee of the uniformity of nature and the persistence of physical law (cc. iv, v). Again, of the popular philosophic arguments which are ".pu* forward as final and conclusive grounds of belief" (p. 138), the argument from general consent is not ultimate; that from success in practice, though it gives us ground for confidence in the future, cannot be conclusive, since it is empirical in character; whilst the argument from common sense which affirms that the intellect, when working normally, is trustworthy, involves a vicious circle, since normal workings can be distinguished from abnormal only on the ground that they lead to truth (c. vii). Similarly the original "deliverances of consciousness", to which Scottish In- tuitionists appeal, are of no avail because it is impos- sible to determine what deliverances of consciousness are original and what are not. Returning to the question of science, Mr. Balfour finds that it contra- dicts common sense in that (e. g.) it declares bodies, which appear coloured to our senses, to be made up in reality of uncoloured particles, and, while thus dis- crediting the trustworthiness of observation, provides no criterion whereby to distinguish observations which are trustworthy from those which arc not. Its method, too, is inconclusive, for there may always be other hypotheses which would explain the facts equally well (c. xii). Lastly the evolution of belief tends