HumanitiesWeb.org - An Essay Concerning Humane Understanding Vol II (BOOK IV - OF KNOWLEDGE AND PROBABILITY SYNOPSIS OF THE FOURTH BOOK.) by John Locke
An Essay Concerning Humane Understanding Vol II BOOK IV - OF KNOWLEDGE AND PROBABILITY SYNOPSIS OF THE FOURTH BOOK.
by John Locke
Locke's review of the different sorts of ideas, or appearances of what
exists, that can be entertained in a human understanding, and of their
relations to words, leads, in the Fourth Book, to an investigation of
the extent and validity of the Knowledge that our ideas bring within our
reach; and into the nature of faith in Probability, by which assent is
extended beyond Knowledge, for the conduct of life. He finds (ch. i, ii)
that Knowledge is either an intuitive, a demonstrative, or a sensuous
perception of absolute certainty, in regard to one or other of four
sorts of agreement or disagreement on the part of ideas:--(1) of each
idea with itself, as identical, and different from every other; (2) in
their abstract relations to one another; (3) in their necessary
connexions, as qualities and powers coexisting in concrete substances;
and (4) as revelations to us of the final realities of existence. The
unconditional certainty that constitutes Knowledge is perceptible by man
only in regard to the first, second, and fourth of these four sorts: in
all general propositions only in regard to the first and second; that is
to say, in identical propositions, and in those which express abstract
relations of simple or mixed modes, in which nominal and real essences
coincide, e. g. propositions in pure mathematics and abstract morality
(chh. iii, v-viii). The fourth sort, which express certainty as to
realities of existence, refer to any of three realities. For every man
is able to perceive with absolute certainty that he himself exists, that
God must exist, and that finite beings other than himself exist;--the
first of these perceptions being awakened by all our ideas, the second
as the consequence of perception of the first, and the last in the
reception of our simple ideas of sense (chh. i. Section 7; ii. Section
14; iii. Section 21; iv, ix-xi). Agreement of the third sort, of
necessary coexistence of simple ideas as qualities and powers in
particular substances, with which all physical inquiry is concerned,
lies beyond human Knowledge; for here the nominal and real essences are
not coincident: general propositions of this sort are determined by
analogies of experience, in judgments that are more or less probable:
intellectually necessary science of nature presupposes Omniscience;
man's interpretations of nature have to turn upon presumptions of
Probability (chh. iii. Sections 9-17; iv. SectionS 11-17; vi, xiv-xvi).
In forming their stock of Certainties and Probabilities men employ the
faculty of reason, faith in divine revelation, and enthusiasm (chh.
xvii-xix); much misled by the last, as well as by other causes of 'wrong
assent' (ch. xx), when they are at work in 'the three great provinces of
the intellectual world' (ch. xxi), concerned respectively with (1)
'things as knowable' (physica); (2) 'actions as they depend on us in
order to happiness' (practica); and (3) methods for interpreting the
signs of what is, and of what ought to be, that are presented in our
ideas and words (logica).
