6. Empirical Science. During the fourteenth and
fifteenth centuries men's attention was increasingly
directed towards this earth. Their interest seems to
have switched from the contemplation of eternal truths
to the control and prediction of the future. Whether
this was astrological or magical or alchemical, whether
it eventuated in exploration and discovery or in exper-
imentation, step by step men reoriented their re-
searches, and the individual, the curious, the novel,
seem to have been of more interest than the traditional,
the authoritative, and the proven. In fact one of the
favorite words for “heresy” was novitas, “novelty.” In
the late fifteenth century Platonism was revived in
Florence in the work of Marsilio Ficino, and after its
revival had a career lasting to the present in one form
or another. But except in the fine arts, it had a recessive
character. The dominant theme was anti-Platonic.
One of the tenets of nominalism was that only indi-
vidual things are real. If this was true, then some
intellectual technique of handling individuals was
needed and that technique did not develop to any great
extent until the seventeenth century when statistics and
the theory of probability became the framework, al-
though a weak one at that time, of scientific thought.
The statistical collection took the place of the Platonic-
Aristotelian class. The idea now became the range of
more or less similar responses to a method of investi-
gation. But that result took four centuries to come to
maturity, and meanwhile the scientifically minded
were satisfied either to call traditional investigators by
bad names or to speak of experience as if its nature
were self-evident.
An Italian “philosopher of nature” like Telesio
(1509-88) might properly be chosen as one of the
initiators of the new science since he selected an easily
identifiable source of change as primordial. Heat and
cold, expansion and contraction, hark back to the pre-
Socratic philosophers, but after centuries of talk about
what exists in terms of what ought to exist, the natural-
ism of Telesio was refreshing. And when Francis Bacon
cleared the air by indicating the obstacles to discovery
in his Four Idols, it was possible to raise the basic
question of the origin of knowledge. To the Neo-
Platonist that origin was inborn in us. To Lord Herbert
of Cherbury (1583-1648) the fundamental principles
of knowledge, both religious and scientific, were innate.
But his opponents argued that if this were so, then
all men ought to agree more than they disagree. And
yet, as John Locke insisted, there is no evidence that
men lacking experience know anything whatsoever.
Ideas emerge not from our untaught minds but from
experience.
Experience now became one of those “sacred
words,” like Nature or Art or Democracy, which
everyone was in favor of and few could define. In
Locke and his successors it came to denote the imme-
diate apprehension of sensory qualities, colors, sounds,
tastes, for instance, plus the ideas of pain and pleasure
or of anything known only to oneself. Locke himself
said that he was using “ideas” to express “whatever
it is which the mind can be employed about in think-
ing” (Essay Concerning Human Understanding, Book
I, Ch. I, Sec. 8). But thinking he identified with aware-
ness. And hence the ideas which in Plato could be
known only after long dialectical analysis now became
something which lay open to the eyes of anyone willing
to look. This was a dramatic reversal of meaning. The
matter was complicated by Locke's conclusion that
some ideas were purely subjective, a conclusion that
dates from the atomism of Democritus in the fifth
century B.C., some copy qualities of the objective and
physical world, and some are known by “bare intui-
tion” (Book IV, Ch. II). But these last do not appear
in Locke's Essay Concerning Human Understanding
until the fourth book is reached, the whole work taking
twenty years (1670-90) for completion. The ideas
known by bare intuition are logical rules, mainly those
derived from the Law of Contradiction.
The development of the theory of ideas in Great
Britain lay in the direction of simplification, passing
through Bishop George Berkeley and David Hume. By
the time Hume had completed his investigations, ideas
had become faint copies of sensory impressions,
whereas in Plato, it will be recalled, they had been
that of which sensory impressions were faint copies.
This was not merely a difference of terminology. For
the Platonic ideas were standards of truth, whereas in
Hume it was the impressions that had become the
standards. The result was that in Condillac and his
successors in the eighteenth century, in Auguste Comte
and the nineteenth-century Positivists, in Ernst Mach
(1838-1916), and in the Viennese Circle in the twen-
tieth century, attempts were made to break down all
ideas into those perceptual data of which they were
presumably composed. One of the difficulties of these
attempts was the admitted existence of Locke's objects
of bare intuition, the logical rules, in short the schemata
of methodology.
