University of Virginia Library

IDEA

Etymologically the Greek word “Idea” is related to
the verbs “to see” and “to know,” and it is not fanciful
to conclude that its primitive denotation was “that
which is seen” or “that which is known.” So in modern
English one says, “I see what you mean,” when “I see”
is equivalent to “I understand.” Thus Pindar (Olympi-
ans 10, 123) could write of a beautiful idea and mean
by it a beautiful sight or form without any implication
that knowledge in the derivative sense of the word is
involved.

The notion that ideas can be apprehended by a kind
of vision or intuition, by looking and seeing them, has
never been lost in Occidental philosophy, for knowing
as a kind of insight, illumination, revelation, has almost
always been retained. The clearest example of this is
the belief that knowledge is of two sorts: one immedi-
ate, sensory, direct grasping of that which is known,
and the other mediated, “intellectual,” inferential.
These two sorts have sometimes been correlated re-
spectively with the Latin cognoscere and scire, the
French connaître and savoir, and the German kennen
and wissen. In English both members of the pairs have
to be translated by the one verb, “to know.” One knows
one's friends and one knows geometry, though the two
experiences are very dissimilar.

1. Plato. Ideas enter philosophy in the dialogues of
Plato. They are an answer to the question, “What do
common nouns signify?” though that is not Plato's way
of putting it. A common noun is obviously peculiar,
as it groups a number of things together instead of
differentiating an individual from all other individuals.
One uses the adjectives which correspond to these
nouns in much the same way. One speaks of a picture
as “beautiful,” of an act as “kind,” of hypocrisy as
“evil,” of apples as “red,” and in doing so one classifies
the objects and acts referred to. But the moment this
is done it is admitted that some properties or qualities
are common to a number of things. Several pictures
may be “beautiful” and things other than apples may
be “red.” The common property therefore is not re-
stricted to any place or date and hence is entirely
different from a material object.

We learn as children that spatiotemporal location
is an essential characteristic of material things. We say
that two material objects cannot occupy the same
space at the same time and that a single material object
cannot be in two places at the same time, a bit of
information which is the basis of an alibi in court. But
a large number of common properties may be present
in a single object and a single common property may
characterize a large number of objects at the same
time. We learn the consequences of this when we study
geometry in school and are warned not to argue from
the looks of the figures that we draw. The triangle on
paper, we are taught, is not the triangle we are discuss-
ing; it is an imperfect representation of the geometri-
cal triangle.

It is possible that Plato's theory of ideas was sug-
gested by these geometrical forms. If we are not study-
ing the triangle drawn on paper, what one are we
studying? The answer usually is: “Something defined
by abstract rules,” or “A plane figure bounded by three
straight lines.” But there are no real planes or straight
lines in human perception and hence we resort to
saying that such things are intellectual constructs, ab-
stract concepts, creations of the mind. Yet we also insist
that they are not imaginary beings like mermaids or
unicorns, for once defined they follow certain laws,
imply certain consequences, and actually control our
thoughts rather than obey them. The sum of the angles
of a plane triangle has to be 180 degrees, neither more
nor less, and we cannot by an act of will or of fantasy
change it. This, however, is true of all common prop-
erties. Once we know what we mean by “beautiful,”
“evil,” “red,” “kind,” we are committed to certain
other assertions which those adjectives presumably
entail.

Plato then is first convinced that ideas cannot be
spatiotemporal like material objects. If they are not
material, some other term must be found for them.
“Mental” will not do since, as we have said, that would
put them in a class with volitions, fantasies, feelings,
and so on. The term used was “eternal” or “timeless.”
The idea of a triangle may be discovered at a certain
date and in a certain place, but it did not come into
being at that place and date. This seems to be true
of all common properties and if so, they may be said
to form a realm of their own existing apart from the
material world. Their interrelations are not causal but
logical. The nature of a plane surface does not cause
three straight lines to be the smallest number to enclose
a plane figure, but it implies that the smallest number
of straight lines that may bound a figure is three.

This being so, no ideas can be known by our sense-
organs. Just as we do not see real triangles, we do not
see real kindness, evil,  beauty , or redness. We see kind
acts but know that they are kind; we see evil deeds
but know that they are evil, and so on. We ask ourselves
whether a certain deed which we observe is really good
or not and it is reflective thought, not perception, that
gives us the answer. The process of reflection is exhib-
ited in the Platonic dialogues. A question is asked, an
answer given, the answer is analyzed to find out if it
is logically consistent, and if it is not, it is rejected.
Many of the dialogues, called by the ancient editors
“dialogues of search,” end at this point.

The ideas then determine what the particular objects
are. It is, for instance, the presence of evil in an act
that makes it evil, the presence of  beauty  that makes
a picture beautiful. This is a cardinal point in Plato's
theory of ideas and the relationship of the particular
thing to the ideas that characterize it was called “par-
ticipation.” The picture participates in  beauty . But
how a spatiotemporal object can participate in an
eternal being was left unclarified. When the matter
is discussed in The Sophist, participation is named and
the limitations of participation defined, but it is clear
that the gap between what was later—by Philo
Judaeus—called the Intelligible World and the Sensible
World was simply accepted by Plato as a fact.

If we cannot perceive the presence of an idea in
our ordinary experience, how do we know what we
are experiencing? The answer was given in the form
of a myth in the dialogue Meno. Since we cannot
apprehend an idea through our sense-organs, we must
come into the world with a stock of them. These are
the innate ideas. They are probably of a mathematical
nature for the most part—ideas of equality, identity,
difference, and similar relations. In the myth it is said
that the soul before birth was in the world of ideas
and that it retained a dim memory of some of them
after birth. As we grow up, the myth continues, on
certain occasions we are reminded of what we knew
in our prenatal life, and we are able to light upon the
idea that fits the case before us. The mythical details
of this need not detain us, though much was made of
them in the Renaissance by the Florentine Platonists,
and they survived to be incorporated in Wordsworth's
Ode on Intimations of Immortality (1806). What is of
greater importance is the suggestion that the human
mind is limited to certain ways of thinking, to certain
logical rules, certain categories of existence, and that
it awakens to these as its education progresses.

This appears in our own day in that theory of teach-
ing known as the “Socratic Method,” according to
which the teacher serves to bring out of the pupil's
mind that which lies hidden in it. In Aristotle these
categories were to be named and in the nineteenth
century they were “deduced” by Kant and his follow-
ers. But as far as Plato is concerned, they are traits
of all ideas and are utilized whenever a person reasons.
Thus all ideas are differentiated from some others; some
are harmonious with some others; some are implied
by some others and naturally imply others. These traits
are known instinctively. Anyone knows that if some-
thing is good, it cannot also be bad at the same time
and in the same respect. But only dialectical training
will teach a person to apply such information in actual
cases of reasoning.

The ideas, since material things participate in them,
are models by means of which we can judge the ade-
quacy or perfection of things. If we know, for instance,
what justice is, we can discover how closely a given
state approaches justice in its constitution. What such
a state would be like is described twice by Plato, once
in The Republic and once in The Laws, his last work.
What is relevant here is the technique by which the
idea of justice is defined. After disposing of a popular
and false definition, Plato begins afresh and comes up
first with the statement that whatever justice may be,
it has terminal value, i.e., it is good in itself and its
by-products, such as happiness, need not be considered.
Hence if just men suffer at the hands of their fellows,
this is of no more importance to the nature of justice
than are the imperfections in the drawings of circles
made in the sand. An idea is always to be discovered
by the dialectical method of question and answer, and
Plato is convinced that a false definition will reveal
its falsity by its inner inconsistencies. We must try to
approximate an idea's perfection as closely as possible,
though knowing that the task is hopeless in real life.

At this point one sees that the idea has become what
we would call the “ideal,” and that the dualism be-
tween the ideal and the existent has widened. This was
to lead to attempts in post-Platonic philosophy to
reduce the duality. And since the ideas or ideals were
accessible only to the reason, two kinds of cognition
were established, perception which grasped the tem-
poral, changing, multiple things in the material world
without knowing what it was grasping, and reason
which knew the eternal, immutable, unified things of
the ideal world. It was the latter world that was “really
real,” the former being a dim reflection of it. Since
only a few human beings, the philosophers, were capa-
ble of reasoning, they would be in charge of the state
if the state were just and perfect. The majority of men
are either led by their appetites or their passions, but
both should be controlled by the reason. The trouble
with society as it exists is that appetitive and passionate
men, who confuse opinion with knowledge, are at its
helm. The Republic and The Laws discuss what must
be done to put them in their proper places.

The ideas then have at least the following properties:
they are universals, class-characters, analogous to
mathematical figures; they are timeless and unchang-
ing; they are ideals, not existent objects in space-time;
they are known only to the reason.

2. Aristotle. At times Plato substitutes the word
eidos for “idea.” Both words are synonymous in his
writings and both are derived from the Greek word
meaning “to see.” But what is seen is a shape or form,
and Plato's pupil, Aristotle, preferred the term eidos,
probably because he could not accept his master's
theory of ideas. Eidos (εἰ̂δος) was translated into Latin

either as species or forma and in English it is usually
called “form.” In order to fill the gap between the
world of ideas and that of things, Aristotle assumed
that the forms were always incorporated in things. That
is, there is no such thing as justice in the abstract; there
are only just people or just acts and we derive our
ideas of justice from the people and acts in which it
is embodied. Thus an idea, though a common property,
might be a form in the sense of the pattern that proc-
esses exemplify; or it might be the shape of finished
works of art.

And, indeed, in reading Aristotle one has the im-
pression that his basic metaphors had a twofold origin,
one in biology and one in the visual arts. A seed or
an egg as it develops always moves to a determined
end, the plant or the chicken, unless it is killed on the
way. This constantly repeated pattern of development,
beginning and ending in the same way, combined
Plato's notion of the idea as the invariable character
of classes of things with the temporal dimension of
growth or of process. The idea or form was “realized”
or actualized in the end-product; but it must have been
somehow present in the origin, the seed or egg, in order
for its realization to be fulfilled. Aristotle named this
kind of presence “potentiality.” The form then was
potentially present in the egg and actually present in
the chicken.

This much was largely explanation by terminology.
But the terminology was made concrete by the example
of artistry. When a sculptor sets out to carve a statue
or a painter to paint a portrait, they have in their minds
an idea of what the finished work of art will look like.
It should be noted in passing that this would not apply
to the so-called romantic artist who does not know how
his work is to terminate until it is finished. We must
assume that the Greek artist was a planner. If Aris-
totle's notion of artistry is correct, the finished statue
exists as an idea in the sculptor's mind before he sets
to work, as a potential form in the marble, and as a
realized form in the finished statue. Just as Nature, so
to speak, guides the egg in its development towards
the chicken, so the sculptor guides the marble towards
the statue.

The form has now taken on the additional character
of being an end or purpose, the “final cause” of a
process. But it may be the purpose of a human being
or a natural purpose—i.e., the end term of a natural
process. It was an easy matter to confuse the two and
think of them as identical, to speak of Nature's pur-
poses or ends when referring to the constancy of physi-
cal law. Or reciprocally to urge men not to modify
their purposes once formed, to be consistent, never to
waver. In fact even by Sir Isaac Newton natural law
was thought of as the decrees of a divine lawgiver,
though Newton was not a believer in final causes.

Aristotle's theory of forms would not have had such
extraordinary influence, if he had not carefully distin-
guished between those processes which are natural and
those which are unnatural. It could not be denied that
sometimes things went awry, that eggs were eaten
before they turned into chickens. A distinction there-
fore was imperative between those ends which were
realized on the whole and those which were only
occasionally realized. The latter were accidental,
brought about by chance; and the former were essen-
tial, brought about by nature. It was clear that things
had a number of properties which were of no scientific
interest. When a physicist is talking of the mass of the
earth, he is not interested in how many continents there
are, who inhabits them, what languages the inhabitants
speak. Mass can be measured without regard to such
things. All science feeds on abstractions and the making
of an abstraction demands the discarding of a number
of differences. If one is discussing humanity as a whole,
one need not bring in skin color, intelligence quotients,
arts and crafts, and kinship tables.

These matters may be of great importance historic-
ally; but they do not distinguish human beings from
the nonhuman, and furthermore they vary from group
to group and in some details from individual to indi-
vidual. They are what Aristotle would have called
accidental traits as contrasted with essential ones. Nat-
ural processes are always the realization of the essential
traits. The realization of accidental traits is no concern
of science.

The identification of the idea or ideal with the form
or essence had certain practical consequences. It meant
that when one was discussing ethics, politics, or art
one had first to discover the essences of the activities
involved and then set up ways of realizing them. In
ethics one had to define the essence of humanity, which
was rational animality, and then investigate what had
to be done to perfect it. The end of human life is
happiness, but all men do not reach that end. Why
not? The end of politics is to make the ethical end
possible. But tyranny, oligarchy, and mob rule stand
in the way. What would have been the end of art was
not stated by Aristotle, for his Poetics is only a frag-
ment, and what it has to say is far from clear. But
in his consideration of tragedy he first tells us what
the essence of tragedy is and then suggests the pre-
requisites for realizing it. This would be standard
Aristotelian procedure. It is easy to see that for it to
work required an intellectualistic psychology. It was
assumed by him, as by Plato, that at least some men
could act in accordance with intellectual motives. This
assumption ran through the writings on normative
sciences up to very recent times when, due to Marx
and Freud probably, action was thought of in terms
of stimuli that were not intellectual.

How did one know what the essences were? In
natural processes they could be determined by that
which occurred always or on the whole. But in human
activities, they were largely determined by tradition.
Aristotle thought, for instance, that his definition of
“tragedy” was based on the actual tragedies written
before his time, which he apparently thought of as
eternal patterns. And though his definition does not
fit all of them, it does well enough for an understanding
of Greek tragedy. But even if he had discovered the
essence of the plays of Aeschylus, Sophocles, Euripides,
and their fellows, that did not imply that later drama-
tists were obligated to imitate their Greek predecessors.
Yet aesthetic theorists and literary critics insisted that
the idea of tragedy as expounded by Aristotle was not
only a generalized description of certain Greek dramas,
but also a rule to be followed by all dramatists for
all time. The idea now became a genetic trait, a form,
an ideal, and a rule.

3. Neo-Platonism. By the third century A.D. a fusion
of Platonic and Aristotelian doctrines had been formu-
lated (also in Greek) by Plotinus, an Alexandrian phi-
losopher teaching in Rome. He accepted the doctrine
that the Platonic ideas formed a world of their own,
that they were universals rather than particulars, and
that they were more real than the particulars for which
they were the models. But he added certain details
which lingered on and which can be found as late as
the end of the eighteenth century, at least in England.
These details, which are neither in Plato nor in Aris-
totle, were foreshadowed in the works of Philo Judaeus
(who was active in the early part of the first Christian
century) and in those of Numenius, a second-century
figure, and probably in others now forgotten. Plotinus'
innovations in the history of the meanings of idea may
be summarized as follows.

(1) The world of ideas in Plotinus forms a hierarchy
at the apex of which were the most real, most general,
best, and most beautiful and at the base of which were
the least real, most particular (individual), worst, and
ugliest. At the very top of the hierarchy is that Idea
which is so general that it can only be called The One.
Immediately below it—or him—is the Intelligence
(Nous) and the Soul of the World. The Intelligence
gives rise to another scale of beings, the Ideas. The
Soul of the World is the source of all the other souls,
of men, beasts, and plants. Reality thus becomes some-
thing which has degrees, matter being the least real
and hence the most evil and the ugliest. It is the com-
plete absence of reality.

(2) By a process called emanation the beings on the
lower levels flow out of those above them like, to use
Plotinus' own metaphor, light from a candle which
disappears finally into darkness. The process of emana-
tion has no source in either Plato or Aristotle; it is
distinctive of Neo-Platonism. It comes to a terminus
in the darkness of the material world, at which level
beings strive to move upward and gain the greater
reality from which they descended. They strive, in
short, to realize the potentialities that are in them. Men
do this by turning away from the bodily life, practicing
asceticism so as to deny their animal and vegetable
nature, engaging in the contemplation of ideas, and
finally merging into the One in a mystic vision. The
process of emanation follows the pattern of a logical
hierarchy, exemplified in biology when varieties are
collected into species, species into genera, genera into
families, families into orders, orders into classes, classes
into phyla, and phyla into kingdoms.

Plotinus' pupil Porphyry bequeathed to posterity a
logical hierarchy which became standard in the teach-
ing of philosophy to beginners. It is called the Tree
of Porphyry.

The classes were subdivided by a technique known as
dichotomy, but neither Porphyry nor anyone else ever
explained where one was to cut a class in two. When
ascending the scale one drops off those characteristics
which differentiate and thus one becomes absorbed into
a more inclusive but simpler class. That is, there are
more sensible beings than rational animals but the
latter group has more traits than the former.

(3) The ideas in Plotinus are known by a special
process sometimes called “intellectual intuition.” They
are not expandible into declarative sentences but are
apprehended as visual objects are apprehended, as
units. Plotinus thought—wrongly—that the Egyptian
hieroglyphs were perceptual presentations of ideas;
later, in the Italian Renaissance, much was made of
this. In fact it was the hint that in all probability
developed into that great mass of writings and draw-
ings known as emblem literature.

(4) The ideas apparently could be presented to the
mind of an individual without the stimulation of an
object. Plotinus held that an artist desiring to make
a statue of Zeus beheld in a sort of vision the idea
of the god and put that into stone.  Beauty  was in fact
the visual presence of the ideal or form and since the

soul was the Aristotelian form of the body, the two
forms responded sympathetically to each other. This
application of the theory of ideas also became impor-
tant in the Renaissance and later, and the doctrine that
painters should paint the ideal rather than the physical
lasted through Ingres into the nineteenth century.

4. Saint Augustine. In Saint Augustine the Platonic
ideas became ideas in the mind of God, ideas in ac-
cordance with which He had created the world. In
the Wisdom of Solomon (11:20) one reads, “... Thou
hast ordered all things by measure and number and
weight,” a verse which during the Middle Ages was
understood to be the basis of all physical science. But
measure and number and weight were mathematical
ideas and since Neo-Platonism was highly colored with
Pythagoreanism, it became almost a rule to identify
the ideas in the mind of God with the mathematical
ideas. The identification was the easier in that numbers
were often associated with geometrical figures, being
at times squares and at other times cubes; the former
symbolizing surfaces, the latter solids. The ideas now
took on qualities that were almost magical: number
symbolism was dilated upon with the greatest enthusi-
asm and it is next to impossible to differentiate the
Neo-Platonic from the Neo-Pythagorean. In Augustine
the symbolism of numbers is dwelt upon at great length
and the numbers which he discusses stand for ideas.
Hence the ideas in the mind of God are really those
mathematical ideas in terms of which He ordered all
things.

This version of what might be called Christian Neo-
Platonism is the foundation of much that we know of
medieval aesthetic theory. It appears in the musical
theories of Boethius (A.D. 480-524) and even, as Otto
von Simson has shown (1956), in the shapes and pro-
portions of Gothic cathedrals. Wisdom 11:20 was to
be illustrated whenever Wisdom (Sapientia) herself was
pictured. And the notion that God created the world
after His archetypal ideas could be used to prove its
perfection and rationality. In short, if science was
possible, that was because Nature was an embodiment
of the divine wisdom.

5. Realism and Nominalism. Plotinus' pupil Por-
phyry, to whom we have already referred, had raised
three questions about the nature of ideas in his Intro-
duction to the Categories of Aristotle.

• (1) Are they beings with independent existence or do they
  exist only as human concepts?

• (2) If they are independent, are they material or immaterial
  beings?

• (3) Do they always exist in sensible objects or not?

These questions were not merely of technical philo-
sophic interest. Church dogma included some state
ments that seemed to be based on the reality of the
universals. For instance, according to Augustine, we
all sinned in Adam because we were in Adam, presum-
ably as particulars participating in a universal. Christ
again, “the second Adam,” could atone for the sins of
mankind, for He was God-made-Man. The Church
Invisible was present in all churches just as God was
entirely present in all three Persons of the Holy Trinity.
These and other dogmas seemed explicable if the ideas,
universals, were real beings, independent of anyone's
mind, and not tied to their incorporation in sensible
objects. As has been pointed out, mathematicians do
not believe that they are talking psychology. Their
subject matter behaves in a manner which no one can
make subservient to his desires or fantasies. How are
other universal ideas different?

The earliest answer to this question, which Father
Copleston, in his Medieval Philosophy (1950), has called
“exaggerated realism,” maintained that universal ideas
were not different in any way. Whenever an idea is
predicated of a subject (e.g., “This is a man”), what
is asserted is the presence of a universal. The theolog-
ical difficulties of this doctrine need not concern us
here. It is of more interest to point out that it turned
the world into an imperfect picture of an ideal design.
The man of the early Middle Ages was to direct his
eyes upward and to think of this world as useful only
as an incentive towards the ideal. In fact it led one
of its proponents, Saint Anselm (1033-1109), to argue
from the reality of an idea to the existence of that of
which it was the idea.

But logical realism was vigorously opposed by a
contemporary of Saint Anselm, Roscellinus. He is said
to have maintained that universals were only names,
a doctrine called “nominalism.” This seemed to some
to imply that when we are discussing ideas we are
talking about words. Mathematics does not appear to
be lexicography nor do any of the natural sciences.
When a physicist talks about gravitation, he may ex-
emplify his point by citing the relation between the
masses of the moon and the earth, but his real subject
matter is much more extensive. Hence the eleventh-
century clash in opinion has not been definitely settled
even today. The Middle Ages, however, were more
fortunate than we. They were given a compromise
solution by Saint Thomas Aquinas. He said that the
ideas have a being independent of things (ante rem)
in the mind of God; they have a being in things (in
rebus) as common characters; they exist in our minds
(post rem) as concepts formed by us through the powers
of abstraction. Like all compromises this raised an
additional problem: how can a single being, justice for
instance, be all three of these things and yet be one
and the same?

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.

7. The Kantian School. These rules and schemata,
the forms of knowledge, were believed by Immanuel
Kant to be unanalyzable into perceptual data. We may
perceive colors and sounds but we cannot perceive the
spatial matrix in which they are located. For if we
empty space of all perceptual content, nothing is left.
Similar arguments apply to time. Hence both space
and time in Kant became the forms of perception, ideas
by which the mind organizes its perceptions but which
have no perceptual correspondence whatsoever. Simi-

larly when we make scientific judgments of causality,
quantity, quality, or necessity, there are no sensory data
which could possibly compose them. These categories
are the means by which we think, and they have no
sources beyond our minds. It had been pointed out in
the seventeenth century by Géraud de Cordemoy and
Nicolas Malebranche that one could see, for instance,
a rolling ball touch another, but one could not see it
cause the other to move.

Causation, then, is an idea of ours which we project
into the world of observation. Similarly Hume had
pointed out that we could observe the regularity of
events but not their necessity. Necessity was one of
our feelings induced by the sight of regularity. Kant's
categories of the understanding were in an analogous
situation. They were the mind's way of making experi-
ence intelligible. They were regulatory principles
which gave structure to our knowledge, knowledge
whose content might be perceptual but whose form
was entirely subjective.

Hume had shown to the satisfaction of most philoso-
phers the impossibility of penetrating the perceptual
screen of impressions and reaching some material cause
which might explain its presence. In Kant the question
of such a cause does not arise, for perceptual ideas
exist as if they were the experiences of a single over-
individual mind. They take the place of an objective
world. But besides these ideas there are the two types
of forms (space, time) and categories through which
all men are bound to order their knowledge. Hence,
as was evident to Kant's immediate successor, Fichte,
any talk about unknowable things-in-themselves is
nonsense. For as soon as we begin to talk, we inescap-
ably use the categories. And the categories are relevant
only to our ideas.

There is moreover another set of ideas in Kant and
these have no ground whatsoever in perception or
science. He recognized that we have religious and
moral ideas, ideas of God, freedom, and immortality.
These ideas cannot be correlated with any perceptions
for the simple reason that we admittedly do not see
(i.e., perceive) what they stand for. Moreover they are
not categories of the understanding, for science not
only can get along very well without them, but actually
contradicts one of them, the idea of freedom, and gives
no evidence for the truth of the other two.

One might conclude that they were false and should
be abandoned. But Kant introduced a new function
for an idea at this point. These three ideas, though
antiscientific, were necessary postulates for ethics.
Doing one's duty would be unjustifiable if there were
no God, if the will were not free, and if life ended
in the grave. Kant did not entertain the possibility that
life is a tragedy and duty an illusion. On the contrary,
he assumed that the world must be so made that doing
one's duty was imperative. Thus a new criterion for
the truth of an idea was introduced, its necessity for
the justification of moral values.

From then on it was possible to think of the world
as essentially a stage for human life and for the solution
of human problems, which was a reversion oddly
enough to the medieval point of view. Philosophy, to
be sure, was no longer the handmaiden of theology
but of ethics. The innovation as it was made by Kant
and developed by Fichte may not have been radical,
but it became so as the nineteenth and twentieth cen-
turies evolved. For if an idea could be a postulate for
the religious and moral life, why could it not be a
postulate for the aesthetic, the political, the economic
life? An idea could easily become an instrument by
means of which a man could substantiate any of his
ends, ends which could be chosen rationally by reasons
which were more useful than true. In such a case the
true would turn into the useful.

Schopenhauer had maintained that reasoning was at
the service of the will-to-live, as Nietzsche was to put
it at the service of the will-to-power. Ideas were a mask
for desires, a doctrine which was developed by Sig-
mund Freud, substituting the libido for the will. The
great Kantian scholar, Hans Vaihinger (1852-1933)
made all ideas fictions of various types which we set
up to make the world intelligible. These and similar
views seemed to dethrone the ideas and to become
not the guideposts to impersonal truth, completely
detached from human desires, forming the matrix of
reality, but rather signs of what we would like to
believe, conventions by means of which we can confer
plausibility upon our thoughts and aspirations. Seldom
has the history of an idea manifested such a reversal
of meaning.

BIBLIOGRAPHY

The literature on the Platonic theory of ideas is very
extensive. Almost anything that has been said about it has
been, and will be, contested. For the most complete list
of articles and books on the subject, see Harold Cherniss,
Lustrum, 1959, No. 4 and 1960, No. 5 (Goettingen, 1960,
1961), pp. 278ff. The most authoritative account of the
entire Platonic philosophy is Paul Shorey, What Plato Said
(Chicago, 1933). For Aristotle's writings as a whole the best
translation is that usually referred to as the Oxford Transla-
tion, by a variety of scholars, in twelve volumes (1910-52).
A single work on Aristotle that is frequently cited is W. D.
Ross, Aristotle, 5th ed. (London and New York, 1955).
But, as is true of Platonism, anything said about Aristoteli-
anism will be contested. There is no satisfactory translation
into English at present of Plotinus but one is promised for
the Loeb Classical Library. For the modern philosophers,
see J. H. Randall, Jr., The Career of Philosophy, to be three

volumes (New York, 1962, 1965, 19—); G. Boas, Dominant
Themes of Modern Philosophy (New York, 1957); and the
various volumes of Frederick Copleston, S.J., A History of
Philosophy (Westminster, Md., 1946-63). Each of these
histories is written from a special point of view which must
be kept in mind when they are consulted. For the influence
of Platonism and Neo-Platonism on art and aesthetics, see
Katharine Gilbert and Helmut Kuhn, A History of Esthetics,
rev. ed. (Bloomington, Ind., 1953). For number symbolism
in the Gothic cathedral, see Otto von Simson, The Gothic
Cathedral, 2nd ed. (New York, 1956).

GEORGE BOAS

[See also Causation; Freedom; Naturalism; Neo-Platonism;
Number; Pragmatism; Primitivism; Pythagorean....]