Metaphysics in Kant and
Post-Kantian Philosophy
Immanuel Kant
Kant’s Copernican Revolution
• Rationalists: universality and necessity require
synthetic a priori
• Hume: source not in the world but in us
• Kant: source is within us— but it is reason, not
custom or habit
Kant’s Categories
• There are innate concepts— the
categories
• They are logical forms of judgment
• They apply only to experience
Knowledge —> Objects
• “It has hitherto been assumed that our knowledge
must conform to the objects; but all attempts to
ascertain anything about these objects a priori, by
means of concepts, and thus to extend the range of
our knowledge, have been rendered abortive by this
assumption. Let us then make the experiment
whether we may not be more successful in
metaphysics, if we assume that the objects must
conform to our knowledge.”
Kant & Copernicus
• “We here propose to do just what Copernicus did in attempting
to explain the celestial movements. When he found that he
could make no progress by assuming that all the heavenly
bodies revolved round the spectator, he reversed the process,
and tried the experiment of assuming that the spectator
revolved, while the stars remained at rest. We may make the
same experiment with regard to the intuition of objects. If the
intuition must conform to the nature of the objects, I do not
see how we can know anything of them a priori. If, on the
other hand, the object conforms to the nature of our faculty
of intuition, I can then easily conceive the possibility of
such an a priori knowledge.”
Laws of the Understanding
“Before objects, are given to me, that is, a
priori, I must presuppose in myself laws
of the understanding which are
expressed in concepts a priori. To these
concepts, then, all the objects of
experience must necessarily conform.”
Limits of Knowledge
• “. . . we only know in things a priori that
which we ourselves place in them.”
• Laws that govern realm of experience are
in us— the laws of the understanding
• So, we can know things only as
experienced by us— not as they are in
themselves
Kant’s Rationalism
• There are innate ideas: pure concepts of the
understanding (the categories)
• There are synthetic a priori truths (laws of the
understanding)
• But they apply only within realm of experience
Phenomena
• Phenomena: appearances, objects as we
perceive them
– Categories apply to them
– A priori principles apply to them
– We can know them with universality and
necessity
Noumena
• Noumena: things-in-themselves,
unconditioned by our cognitive faculties
– Categories don’t apply to them
– A priori principles don’t apply to them
– We can’t know them at all
Descartes/Hume/Kant
Descartes
Hume
Kant
Synthetic
a priori?
Yes
No
Yes
Knowledge
Beyond exp.
Yes
No
No
Yes
No
No
Knowledge
of world as
it is
Plato’s Philosophy of Mind
The Good
•
Participation
This is a
triangle
Form
Recollection
Perception
Object
Kant’s Philosophy of Mind
•
Construction
This is a
triangle
Concept
Perception
Object
Kant’s Philosophy of Mind
•
Understanding
This is a
triangle
Concept
Appearance
Sensibility
Thing in itself
G. W. F. Hegel
Hegel
• Georg Wilhelm Friedrich Hegel (1770-1831)
was perhaps the last great philosophical
system builder
• His distinctively dynamic form of idealism set
the stage for other nineteenth-century
Western philosophers
• Hegel, like Kant, is an idealist: Everything
depends on mind
• The world as we know it is something we
construct
Critique of Kant
• Noumena (things-in-themselves) play no role in
Kant’s system
• The pure concepts of the understanding do not
apply to them
• So, they do not fall under the categories
• We cannot say that things-in-themselves, in
combination with our cognitive faculties, cause
things to appear as they do, for causation is one of
the categories
• We cannot even officially say that things-inthemselves exist!
Historicism
• Kant maintained that we could have universal
and necessary knowledge of the world by
uncovering the laws of the understanding
• To give us universal and necessary knowledge,
those laws must be constant; they must be the
same for each person, in all times and
circumstances
• Why, however, should we expect human beings
to construct the world in the same way, at all
times and places, in all circumstances, in all
cultures?
Historicism
• Hegel contends that the way in which we
construct the world develops systematically
over time
• Philosophy, like other aspects of human
thought, thus varies with historical
circumstances
• “Philosophy is its own time raised to the
level of thought.”
Absolute Spirit
• Hegel tells the story of Spirit or Mind (in
German, Geist), which progresses
through a variety of stages to reach
Absolute Knowledge
Dynamic Principles
• This is not to say that philosophy cannot
express any universal or necessary truths
• But they are not the kinds of truths sought by
Kant or other previous rationalists
• What stays constant across historical
circumstances are not a priori propositions or
innate concepts but the set of dynamic
principles governing the development of our
ways of constructing the world
Dynamic Principles
• Hegel finds some universal and
necessary truths
• But they are high-level, dynamic
principles governing the development of
thought
• The best known is the thesis-antithesissynthesis pattern
Thesis
• People adopt a certain way of looking at
and thinking about the world (the thesis)
• Because it is only partially correct, over
time people encounter contrary
evidence, counterexamples, anomalies,
and contradictions
Antithesis
• Inspired by these, they shift to a new
and contrary way of looking at and
thinking about things (the antithesis).
• That too is only a partial truth, however,
so it also gradually confronts contrary
evidence, counterexamples, anomalies,
and contradictions.
Synthesis
• The conflict between thesis and
antithesis is eventually transcended in a
synthesis that draws elements from
both while transforming the way people
see and think
• That becomes a new thesis, and the
process begins again
Social Character of Thought
• Hegel sees human thought as essentially social
• The social and historical context of thought is
crucial
• We learn our language, which provides our basic
categories of thought, from other people, at a
particular time, in the context of a particular society
• What Kant and other rationalists take as stemming
from our nature as knowers Hegel sees as
reflecting a specific social background
Dynamics of the Self
• Hegel, rejecting things-in-themselves, sees
the unity of the self not as a given but as an
achievement
• His Phenomenology of Spirit
(phenomenology = study of phenomena, that
is, appearances) traces the development of
the self through a variety of stages, including
one he famously terms “unhappy
consciousness”
Unhappy Consciousness
• The self is divided, alienated from itself
• We overcome that alienation socially
• We achieve self-consciousness by
– recognizing other people as self-conscious
agents,
– being recognized as selves by them, and
– recognizing that recognition ourselves
• We become integrated selves by being seen
as such by others we recognize as selves
Myth of the Given
• Hegel rejects what he refers to as
immediacy, the sharp divide in Kant and the
empiricists between sensibility and
understanding— between perception and
conceptual knowledge
• Hegel denies that we can distinguish any
given, preconceptual portion of our
experience. The concepts we have shape
the way we perceive the world
Relativism
• Relativism: truth is relative to
– Individual
– Society
– Culture
– Interpretive community
– Historical epoch
– Conceptual framework
Friedrich Nietzsche
• Nietzsche (18441900)
• Historicism: truth is
relative to a historical
period
Nietzsche
• Truth doesn’t develop rationally,
according to any discernible laws
• It is irrational, driven by the will to power
• Two-level theory: “What if this chemistry
would reveal that in these areas too the
most glorious colors arise from low,
despised materials?”
Historicism and Relativism
• “Everything, however, became what it
is. There are no eternal facts. There are
no absolute truths. Therefore what is
needed from now on is historical
philosophizing and with it the virtue of
modesty.”
Interpretation
• Knowledge doesn’t progress according
to laws
• It doesn’t necessarily progress at all
• Science must become playful,
developing new ways of seeing and
interpreting the world
World as Projection
• “Because we looked at the world for thousands of
years with moral, aesthetic, religious demands, with
blind inclination, passion, or fear, and abandoned
ourselves to the bad habits of illogical thinking, this
world has gradually become so wondrously
multicolored, terrible, meaningful, soulful, that it has
taken on color—but we have been the colorists. The
human intellect projected its errors as appearances
and its basic assumptions into things.”
God is Dead
• “New struggles.—After Buddha was
dead, his shadow was still shown for
centuries in a cave—a tremendous,
shiver-inducing shadow. God is dead;
but given humans as they are, there
may be caves for thousands of years in
which his shadow is shown.—And we—
we still have to defeat his shadow!”
The Madman
• “Have you not heard of that madman,
who lit a lantern in the bright morning,
ran to the market and cried incessantly:
—‘I’m looking for God! I’m looking for
God!’”
The Madman
• “As there were many who stood together
there who did not believe in God, he excited
much laughter. Is he lost? said one. Did he
wander off like a child? said another. Or does
he keep himself hidden? Is he afraid of us?
Did he go to sea? emigrate?—in such a way
they laughed and yelled in disorder.”
• Nietzsche here echoes Elijah taunting the
priests of Ba’al (1 Kings 18:27).
The Madman
• “The madman jumped into their midst
and pierced them with his gaze. “Where
is God?” he cried. “I will tell you! We
killed him—you and I! We all are his
murderers!”
The Madman
• “God is dead! God remains dead! And
we killed him! How can we comfort
ourselves, the murderers of all
murderers? …Isn’t the size of this deed
too large for us? Don’t we have to
become gods just to appear worthy of
it?”
Revaluation of Values
• “What do you believe?—This: that the
weights of all things must be determined
afresh.”
Authenticity
• “What does your conscience say?—
‘You are to become the person you
are.’”
Coherence Theory
• A sentence or belief is true if it coheres
with a comprehensive theory of the world
• Francis Herbert Bradley (1846-1924)
decries facts as a "vicious abstraction."
• Holism: explain parts in terms of wholes
• Explain things in terms of context, function
Coherence
• We cannot evaluate knowledge claims apart from
an entire system
• A true belief coheres with a maximally coherent
and comprehensive system of beliefs
• So, to assess the truth of a belief, we must see
how it fits with our best overall system
• We cannot evaluate beliefs one-by-one; we must
evaluate them in the context of a system
The Web of Belief
• Experience
Objections to Coherence
• Defining truth in terms of coherence would
be circular
– Coherence –> consistency: can all be true
– But then coherence is defined in terms of truth
Objections to Coherence
• Could there be more than one
comprehensive and coherent system of
beliefs?
• What about the world?
Charles Sanders Peirce
(1839-1914)
Pragmatism
• Charles Sanders Peirce develops the
pragmatic theory of truth
• Principle of pragmatism: There is no
difference in meaning without a difference in
practice
Pragmatism
• Meaning depends entirely on practice
• To get clear about the meanings of our
terms and thoughts, we need to be clear
about their practical antecedents and
effects
Scientific Inquiry
• Thought aims at truth. Not all practice
does
• But scientific inquiry aims at truth
• It aims in particular at stable belief:
beliefs that will not have to be given up
in the face of further information
Defining Truth
• The correspondence theorist defines
scientific activity as that activity that
aims at the truth
• Peirce defines the truth is that at which
scientific activity aims
Peirce on Truth
• “The opinion which is fated to be ultimately
agreed to by all who investigate, is what we
mean by the truth, and the object represented
in this opinion is the real.”
Limit of Scientific Inquiry
• Truth, then, is a kind of coherence (or, as
Peirce prefers to call it, concordance)
• with the ideal limit of scientific inquiry
• The truth is what we all eventually are bound
to agree on
Belief Revision
• Science is a process of belief revision
• When we encounter new information and
update our beliefs, we keep some, reject
others, and add new ones
• Truth is what works in that context of belief
revision
• Truth is that on which our process of belief
revision stabilizes
Bertrand Russell (1872-1970)
Missing Explanation
• But why do we all eventually agree on,
say, p?
• The realist/correspondence theorist can
say, because p is true
• What can the pragmatist say?
Argument for Idealism
• We have reason to believe that something
exists only if we can know it
• We can know an object only by making it an
object of consciousness
• Any object of consciousness is conditioned by
consciousness
• Anything conditioned by consciousness is minddependent
• So, we have reason to believe that a thing
exists only if it is mind-dependent
The Realists’ Critique
• Premises 3 and 4:
– Any object of consciousness is conditioned by
consciousness
– Anything conditioned by consciousness is minddependent
• Realists: I see a cat. It becomes an object of
consciousness. So, the cat is conditioned by
consciousness? So, the cat is minddependent? That’s absurd! The cat isn’t
affected by my seeing or not seeing it.
Equivocation in Idealism
• G. E. Moore’s “The Refutation of Idealism”
• The idealists use ‘object of consciousness’
ambiguously
• Actual objects (causes of perception— things-inthemselves) vs. internal objects (effects—
appearances)
Equivocation in Idealism
• We know actual objects by representing them
as internal objects
• The internal object is conditioned and minddependent; the actual object is neither
• Common Sense: “There are at least two
material objects in the universe.”
Actual Objects
• Actual objects— things-in-themselves— are
not conditioned by being known
• But they can be known— by being
represented as internal objects, as
appearances
• Representationalism: We know things-inthemselves by representing them to
ourselves as appearances
Idealist’s Argument Revised
• We have reason to believe that something [an actual
object] exists only if we can know it
• We can know an [actual] object only by making it an
[internal] object of consciousness
• Any [internal] object of consciousness is conditioned by
consciousness
• Anything conditioned by consciousness is minddependent
• So, we have reason to believe that a thing [an actual
object] exists only if there is a mind-dependent internal
object.