EPISTEMOLOGY
507
EPISTEMOLOGY
critical logic, critical or initial philosophy, etc. To
the same part of philosophy the name criteriology is
given by the authors of some Latin textbooks and by
the Louvain School. The exact province of epis-
temology is as yet but imperfectly determined, the
two main views corresponding to the two meanings of
the Greek word eTnaT-fiii-q. According as this is under-
stood in its more general sense of knowledge, or in its
more special sense of scientific knowledge, epistemol-
ogy is "the theory of the origin, nature and limits of
knowledge ' (Baldwin, " Diet, of Philos. and Psychol. ",
NewYork, 1901,s.v."Epistemology",I,333; cf. "Gno-
siology", I, 41-1); or " the philosophy of the sciences",
and more exactly, " the critical study of the principles,
hypotheses and results of the various sciences, de-
signed to determine their logical (not psychological)
origin, their value and objective import' (" Bulletin de
la Societefrangaisede Philos.", June, 1905, fasc.no. 7 of
the Vocabulaire philo.sopliique, s. v. " Epistemologie",
221 ; cf . .\ug., 1906, fasc. 9 of the VocabuL, s. v. " Gno-
seologie", 332). The Italian usage agrees with the
French. According to RanzoU (" Dizionario di scienze
filosofiche", Milan, 1905, s. v. "Epistemologia", 226;
cf. "Gnosiologia", 286), epistemology "determines the
objects of every science by ascertaining their differenti-
ating characteristics, fixes their relations and common
principles, the laws of their development and their
special methods". Here we shall consider epistemol-
ogy in its first and broader meaning, which is the usual
one in English, as applying to the theory of knowl-
edge, the German Erkenntnistheorie, i. e. "that part of
philosophy which, in the first place, describes, analyses,
examines genetically the facts of knowledge as such
(psychology of knowledge), and then tests chiefly the
value of knowledge and of its various kinds, its con-
ditions of validity, range and Umits (critique of know-
ledge) " (Eisler, Worterbuch der philos. Begriffe, 2d
ed., Berlin, 1904, 1, 298). In that sense epistemology
does not merely deal with certain assumptions of
science, but undertakes to test the cognitive faculty
itself in all its functions.
Historical Outlive. — The first efforts of Greek thinkers centre around the study of nature. This early philosophy is almost exclusively objective, and supposes, without examining it, the validity of knowl- edge. Doubt arose later chiefly from the disagree- ment of philosophers in determining the primordial elements of matter and in discussing the nature and attributes of reality. Parmenides holds that it is un- changeable; Heraclitus, that it is constantly chang- ing; Democritus endows it with an eternal inherent motion, while Anaxagoras requires an independent and intelligent motor. This led the Sophists to ques- tion the possibility of certitude, and prepared the way for their sceptical tendencies. With Socrates, Plato, and Aristotle, who oppose the Sophists, the power of the mind to know truth and reach certitude is vindi- cated, and the conditions for the validity of knowledge are examined. But epistemological questions are not yet treated on their own merits, nor kept sufficiently distinct from purely logical and metaphysical in- quiries. The philosophy of the Stoics is primarily practical, knowledge being looked upon as a means of right living and as a condition of happiness. As man must act according to guiding principles and rational convictions, human action supposes the possibility of knowledge. Subordinating science to ethics, the Epi- cureans admit the necessity of knowledge for conduct. And since Epicurean ethics re.sts essentially on the experience of pleasure and pain, these sensations are ultimately the practical criterion of trutli. The con- flict of opinions, the impossibility of demonstrating everything, the relativity of perception, became again the main arguments of scepticism. Pyrrho claims that the nature of things is unknowable, and conse- quently we mu.st abstain from judging; herein consist bumaa virtue and happiness. The representatives of
the Middle Academy also are sceptical, although in a
less radical manner. Thus Arcesilaus, while denying
the possibility of certitude and claiming that the duty
of a wise man is to refuse his assent to any proposition,
admits nevertheless that a degree of probability suffi-
cient for the conduct of life is attainable. Carneades
develops the same doctrine and emphasizes its scepti-
cal aspect. Later sceptics, ^Enesidemus, Agrippa,
and Sextus Empiricus, make no essential addition.
The Fathers of the Church are occupied chiefly in defending Christian dogmas, and thus indirectly in showing the harmony of revealed truth with reason. St. Augustine goes farther than any other in the analy- sis of knowledge and in the inquiry concerning its validity. He wrote a special treatise against the sceptics of the Academy who admitted no certain, but only probable, knowledge. What is probability, he asks in an argument ad hominem, but a likeness of or an approach to truth and certitude? And then how can one speak of probaliility who does not first admit certitude? On one point at least, the existence of the thinking subject, doubt is impossible. Should a man doubt everything or be in error, the very fact of doubts ing or being deceived implies existence. First logical principles also are certain. Although the senses are not untrustworthy, perfect knowledge is intellectual knowledge based on the data of the senses and rising beyond them to general causes. In medieval philoso- phy the main epistemological issue is the objective value of universal ideas. After Plato and Aristotle the Scholastics hold that there is no science of the individual as such. As science deals with general principles and laws, to know how far science is legiti- mate it is necessary to know first the value of general notions and the relations of the universal to the in- dividual. Does the universal exist in nature, or is it a purely mental product? Such was the question raised by Porphyry in his introduction to Ai-istotle's "Categories". Up to the end of the twelfth century, the answers are limited to two, corresponding to the two possibilities mentioned by PorphjTy. Hence if one may speak of Realism at that period, it does not seem altogether correct to speak of Conceptualism or Nominalism in the well-defined sense which these terms have since acquired (see De Wulf, Hist, de la phil. m{5di6vale, 2d ed., Louvain, 1905). Later, a distinction is introduced which St. Thomas formu- lates clearly and which avoids both extremes. The universal as such does not exist in nature, but oidy in the mind. Yet it is not a mere product of mental activity; it has a basis in really existing things; that is, by their individual an<l by their common features, existing things offer to the mind a basis for the exer- cise of its functions of abstraction and generalization. This moderate Realism, as it is called in opposition to Conceptualism on the one side, and, on tlie other, to exaggerated, or absolute Reahsm, is also essentially the doctrine of Duns Scotus; and it prevailed in the School till the period of decadence when Nominalism or Terminism was introduced by Occam and his fol- lowers.
In modern times Descartes may be mentioned for his methodical doubt and his solution of it in the Cogilo, ergo sum, i. e. I think, therefore, I exist. But Locke, in his " Essay concerning Human LTnderstand- ing", is the first to give a clear statement of episte- mological problems. To begin with ontological dis- cussions is to begin "at the wrong end" and to take "a wrong course". Hence "it came to my thoughts that . . . before we set ourselves upon inquiries of that nature, it was necessary to examine our own abil- ities, and to see what objects our understandings were, or were not fitted to deal with" (Epistle to the Reader). Locke's purpose is to discover "the cer- tainty, evi<lence and extent" of human knowledge (I, i, 3), to find "the horizon which sets the boun<is between the enlightened and dark parts of things,
