This article is about the philosophical notion of Idealism. Idealism is also a term in international relations theory and in Christian eschatology.
Idealism is a term used to describe a wide variety of
philosophical positions. One can distinguish two general senses: A
Platonic sense, and a modern sense. Idealism in the Platonic sense
involves the claim that ideal things occupy a metaphysically privileged
position in the universe. Idealism in the modern sense centers around
the claim that at least large portions of reality (in particular, the
experienced physical world) are metaphysically based in something mental
(minds and their ideas or representations). Such a view stands in stark
opposition with "materialist" views of reality, which claim that mental
entities and properties are somehow based or grounded in non-mental,
material entities and properties, of the sort with which physics is
concerned (there are positions between the two extremes, such as
dualism).
Though both types of idealism are first and foremost metaphysical
positions, their proponents have typically tried to motivate them using
epistemological considerations. Plato's concern with the ideal realm
appears to have been largely motivated by questions concerning
knowledge. Epistemological arguments play a central role in the defenses
of modern idealism presented by the two most prominent idealists in
modern Western philosophy: George Berkeley and Immanuel Kant. Though
there are relations between the two types of idealism, this article will
discuss them separately.
Platonic idealism
In Book VII of the Republic, Plato presented his famous "Allegory
of the Cave," which stands as one of the most vivid images of Platonic
idealism. Taken together with Book VI's sun metaphor, the picture that
emerges is roughly as follows: Certain entities ("Forms") stand at the
basis of reality. These things are ideal, not in a pictoral sense, but
rather in the sense that they represent a sort of perfection. For
example, the Form of the Good is the only entity that is entirely good.
Other entities have some degree of goodness only by "participating" in
the Form. Sensible objects have the properties they do participating
imperfectly in a large number of Forms. This "participation" makes them
somehow less real than the Forms, so that Plato describes them as mere
shadows or reflections. Throughout the relevant discussion, Plato is
clear that the metaphysical relation between sensible objects and Forms
perfectly parallels (and, it is safe to assume, was inspired by) the
epistemic relations between perceptual awareness of sensory particulars
and intellectual awareness of abstract universals.
In the Republic, the relation of the Forms to the rest of reality
received little more than a metaphorical explanation. The Forms were
somehow (perhaps causally) responsible for the sensible world, but Plato
gave no suggestion that illumination was possible on that front. In his
(probably later) dialogue Timaeus, however, Plato presented a
creation story that suggested a picture more in line with most religious
orthodoxy (both as Plato knew it, and as what it would become). In the Timaeus,
the world is created when a powerful demiurge (meaning "craftsman")
shapes the physical world in the images of the Forms, which act as
blueprints.
The Timaeus was one of the most influential of Plato's works for
the Christian Platonists. Heavily influenced by that account, Augustine
rejected the idea that God merely shaped the world at some point
in time, and rather held that God timelessly created the world. Such a
timeless creation was in many ways closer to the picture originally
presented in the Republic. Augustine also rejected the picture of
the Forms as independent of and prior to God, instead locating such
eternal archetypes in God alone.
Versions of such a view lasted even into the modern era. The great
German philosopher Leibniz held that God's understanding contained ideas
of all possible things, and that his act of creation was simply him
actualizing the combination of things that he knew to be best.
Modern idealism
Overview of modern idealism
In the first section of his 1783 work, Prolegomena to Any Future Metaphysics,
Kant defined "genuine" idealism as consisting in the assertion that,
"there are none but thinking beings; all other things which we believe
are perceived in intuitions are nothing but representations in the
thinking beings, to which no object external to them corresponds"
(4:288-89 in the Akademie edition). The view described here applies as
well to Leibniz as to Berkeley. It involves a sweeping claim about the
nature of reality—namely, that the very notion of something
entirely non-mental existing is either incoherent (Berkeley) or else
cannot survive philosophical reflection (Leibniz).
Kant offered this definition, however, in order to distance himself from such positions (when writing the Prolegomena, he was reeling from reviews of his 1781 Critique of Pure Reason
which charged him with merely restating Berkeley's position). His view,
which he described as "transcendental" or "critical" idealism
(4:293-94), did not involve the claim that all non-mental things must exist in representations.
The distinction Kant aimed to draw can be turned into a useful general
point. It is clearest to understand the term "idealism" in a relative
sense and an absolute sense. In the relative sense, a philosopher is an
idealist about a certain sort of entity or property, where this
simply means that she believes that the existence and nature of that
entity or property ultimately reduces to facts about minds and their
representations. Given this, certain forms of idealism should be
generally accepted—for instance, we might be idealists about a certain
fictional character. Kant, then, was an idealist about a certain set of
properties (including space and time), but not about others (for
instance, the property of being able to affect other entities).
The absolute sense of "idealism," then, is relative idealism about all
entities and properties. This is then a much stronger position, and one
that cannot be conclusively argued for one entity or property at a
time.
George Berkeley
Inspired by the work of the French philosopher and theologian Nicolas
Malebranche, the Irish Bishop George Berkeley believed that
philosophical positions that posited absolutely non-mental entities in
the universe (in particular, Cartesian material substance) were
responsible for the spread of atheism and skepticism across Europe in
the seventeenth and eighteenth centuries. According to a philosophical
picture such as that advanced by John Locke, material substance was the
crucial aspect of the physical world, and was responsible for causing
representations in the mind. It could not, however, be directly
perceived, and could only be known indirectly through the
representations it caused.
But if material substance was at the core of physical reality and could
not be directly known, then, Berkeley believed, it was inevitable that
people would come to doubt whether it existed, and thereby come to
question the reality of the world of everyday objects. Worse, in his
view, this view described a universe that seemed capable of operating
independently of God. Were people to become convinced of such a picture,
it was inevitable that they would come to wonder if they had any reason
for believing in God at all.
On the other hand, if people believed (1) that all that existed were
minds and their representations, (2) that the world of everyday objects
was simply composed of representations, and (3) that most of their
representations were directly caused by God, then the source of those
temptations towards skepticism and atheism would dry up.
In his two major works, the Principles of Human Knowledge (1710) and Three Dialogues Between Hylas and Philonous
(1713), Berkeley presented two general arguments for his idealism: The
first based on the differing representations we have of supposedly
unchanging objects, and the second based on the very conceivability of
something non-mental.
The first general argument might be schematized as follows: Our
perceptions of objects change with changes in us (e.g. objects appear
different shapes from different perspective angles), but, on the view
that there exists some non-mental material substance, the underlying
substance needn't change with (e.g.) changes in our position. Yet there
is no non-arbitrary way of determining which of those changing
perceptions is correct, in the sense of revealing the true nature
of the object. Because those perceptions are often incompatible, they
cannot all reveal the nature of the object, but since they are all on
par, the only reasonable conclusion is that none of them do. But that,
Berkeley claimed, is obviously absurd; of course human
perceptions say something about the nature of the object. That's why
people use their perception in the first place. Given this, he thought
that the only reasonable alternative was to identify the object with
one's perceptions of it, thereby allowing one direct epistemic access to
it (this relied on the uncontroversial assumption that people have
direct access to their perceptions).
The first argument, however, is not nearly strong enough to establish
absolute idealism, which was Berkeley's aim. It leaves open the
possibility that the objects people perceive have an unknown reality, as
well as the possibility that there might be unperceivable and
non-mental objects. To rule out those possibilities, Berkeley presented
another line of argument. Accepting a strong form of empiricism,
Berkeley claimed that the only understanding of "existence" one can have
must be one derived from his experiences. Human experiences, however,
are all of one's own mind and one's own representations. But in that
case, the only meaning that existence can have is "to have a
representation or be a representation." Material substance, however,
was supposed to be something that was neither a representation nor a
possessor of representations. The conclusion is that "material substance
exists" is in fact a contradiction.
Kant
Berkeley's second argument (presented above) relied heavily on the claim
that all of one's meaningful thoughts must be based in direct
experience. While this thought has appealed to some philosophers
(perhaps most notably in the twentieth century, the logical
positivists), it strikes most people as highly problematic. For
instance, people seem to be able to think thoughts with universal and
necessary content (for instance, all events have a cause), even though
experience alone seems insufficient to yield ideas of universality or
necessity.
Motivated by just such thoughts, Kant rejected the strong empiricist
assumptions that underlay Berkeley's most radical arguments.
Nevertheless, in his Critique of Pure Reason, he advanced
arguments for forms of relative idealism about almost all qualities of
objects, including their spatiality, temporality, and all sensible
qualities.
With respect to space and time, Kant believed that some form of idealism was required to explain the vast store of a priori
knowledge people have concerning the spatial and temporal properties of
objects (the clearest example being geometry). How, Kant wondered,
could people know, as they doubtless do, that all objects they could
encounter have a spatial relation to each other and can be described
mathematically? After all, people have experienced only a minute
fraction of what exists, so they are hardly in a place to draw any
inductive inference to such a conclusion. The only way one could explain
this bulk of necessary, universal knowledge, Kant believed, was if
space and time only existed as representations in the mind that one imposes on objects she encounters.
Nevertheless, Kant was clear that this does not mean that the objects people encounter only exist
in their representations. The objects exist on their own—it is rather a
certain set of their properties that are ideal. They almost certainly
have other properties beyond those people encounter, and those
properties needn't have any relation to anything mental. Kant often puts
this distinction in terms of a contrast between "things as they appear
to us" and "things as they are in themselves." By emphasizing ignorance
of how things are in themselves, Kant hoped to rule out the possibility
that natural science (which has to do only with things as they appear)
could disprove the existence of freedom of the will or the existence of
God.
German idealism
Kant's idealism was enormously influential. Many of his successors,
however, believed that his insistence on the existence of things in
themselves showed that he had not taken his own insight concerning
knowledge seriously enough. If knowledge only concerns representations,
they thought, how could one even know the possibility of
something outside of those representations? How could that even make
sense? In response to these worries, absolute idealism surfaced again
in Germany in the work of such thinkers as Fichte and Hegel. This issued
in the era known as "German Idealism."
Fichte and Hegel's views are present in some of the most difficult pieces of philosophy ever produced (e.g. Fichte's Theory of Science or Wissenschaftslehre and Hegel's Phenomenology of Spirit).
Yet the core idea is relatively simple: Whereas Berkeley believed that
some supremely powerful mind (God) was needed to explain the varied
perceptions humans experience, and Kant explained experience in terms of
interactions with things whose inner natures humans were unaware of,
Fichte (in his later work) and Hegel believed that such explanations
could come from features internal to the force that manifests itself in
finite minds (some sort of general mental force).
The advantage of such a move was that there was no longer an appeal to
anything as supernatural as God or things in themselves. The
disadvantage is the resulting difficulty in explaining how features of
one's own mind could possibly account for the wildly varying and deeply
complex set of representations we experience.
Despite this daunting philosophical challenge, the philosophical picture
proposed by the German Idealists was extremely influential. It enjoyed a
surge of popularity in English speaking countries in the late
nineteenth and early twentieth centuries, as present in such figures as
F.H. Bradley, J.M.E. McTaggart, and Josiah Royce.
Criticisms of idealism
The most natural response to idealism is that it violates some tenet of
common sense. Berkeley was well aware of this, and spent much of his Three Dialogues attempted to argue to the contrary.
Yet a sustained philosophical attack on idealism was made (largely in
response to Hegelian idealism) by the British philosopher G. E. Moore in
the early twentieth century (Bertrand Russell made a parallel attack).
Moore directly attacked that essential assumption of idealism, that what
people are directly aware of are their representations. Instead, Moore
proposed that people should understand the objects of their thoughts to
be propositions, where propositions can be understood as states
of affairs constituted by genuinely non-mental objects in the world.
Such a picture has become the dominant one in contemporary analytic
philosophy, and idealism is not often counted as a viably philosophical
position. Nevertheless, defenders of idealism may well note that Moore's
alternative picture is no more self-evident than the picture it meant
to replace, so that the matter is far from settled.