Immanuel Kant
Critique of Pure Reason
Historical Context
 Kant lived during the age of enlightenment
 The spirit of enlightenment (Aufklaerung):
 1. Universalism: The thinker tried to reflect the
cultural development of science and economics
as new era in humanity
 2. Struggle against religious worldview: Religion
was seen as superstition that must be clarified
by an scientific explanation of the reality.
 3. The alternative Worldviews: a. Deism
(England); b. Materialism (French). In Germany
the enlightenment was not radical and tended to
a synthesis of all contrary streams.
The Project of Kant’s Philosophy
 Kant’s philosophical project can be formulated in
three questions:
 1. What can I know? The Answer is the content
of “Critique of pure Reason” [Kritik der reinen
Vernunft]
 2. What should I do? The Answer is the content
of “Critique of practical Reason” [Kritik der
praktischen Vernunft]
 3. What can I hope? The Answer is the content
of “Critique of Judgment” [Kritik der Urteilkraft]
Kant’s Approach to the Problem of
Knowledge - Criticism
 Kant’s Philosophy is called “criticism”. It can be
defined as a philosophy that is critical against
the dogmatism. Dogmatism is a form of
knowledge that is achieved without researching
first the condition of possibility [die Bedingung
der Moeglichkeit] of our knowledge capacity.
E.g. metaphysics. Contrary to it the criticism is a
form of knowledge that is achieved, after we
question first the limits of our capacity to know
the reality.
Proceduralism
 For Kant it is more interesting to know the form
of our knowledge than the content of our
knowledge. Therefore he focused his research
on the procedure by which we get our
knowledge of reality. So, his epistemology is a
research on the validity of our knowledge.
 He wanted to know, if the mathematics, physics
and metaphysics are valid as science or not.
 Valid as science means that they can give us a
reliable knowledge that has empirical evidence.
The Main Problem of “Kritik der reinen
Vernunft”
 Kant asks, how the synthetical judgment like “all events
in the world has a cause” is possible.
 “all events in the world” = subject of the sentence
 “has a cause” = predicate of the sentence
 The predicate is not the analytical result of the subject,
but gives us a new information (so, it is synthetic, and
not analytic)
 However all the sentence is a priori (a priori synthetic):
We needn’t to find the causes of all events in order to
justify the truth of his sentence.
 So, Kant’s question is: How is the a priori
synthetical judgment in Physics possible?
Three Levels of Knowledge
Kant answers the question in that he
sketches the process of our knowing
activity as three levels:
1. Transcendental Aesthetics (Knowledge
on the sensuous level)
2. Transcendental Analytics (Knowledge
on the intellectual level)
3. Transcendental Dialectics (Knowledge
on the rational level)
The Phenomenal and Noumenal
 According to Kant we don’t know the thing in
itself (das Ding an sich). We know only the
appearance of the table, for example, but the
table in itself, i.e. the essential table, cannot be
known.
 The table that we see is the combination
between the result of our sensuous activity and
the appearance of the object that is caused by
“das Ding an sich” beyond the empirical reality.
 The table lies on the phenomenal field of reality
 The table in itself lies on the noumenal field of
reality
I. On the sensuous level (Sinnlichkeit)
 On this level our knowledge on the table is a
combination between a priori and a posteriori
elements:
 A priori on the side of knowing subject: our
senses have a priori of space and time
 A posteriori on the side of known object: the
appearance of the table is chaotic without the a
priori of the subjective side of knowledge.
 The a priori can be illustrated as glasses.
Without then the reality outside seems blur.
 On this level Kant justifies Mathematics as
science, because space and time are our a priori
Space as a priori
“Space is not an empirical concept…the
representation of space cannot be
borrowed through experience from
relations of external phenomena, but, on
the contrary, this external experience
becomes possible only by means of the
representation of space” (Kant, Chritique
of Pure Reason, in: Baird, p. 492)
Time as internal sense
“Time is nothing but the form of the
internal sense, that is, of our intuition of
ourselves, and of our internal state…Time
ist the formal condition, a prioru, of all
phenomena whatsoever…”
II.The Intellectual Level (or Verstand)
 On this level our mind combines two or more separated
phenomena. E.g. “The table is damage because of fire”
 How it combines “table” and “fire”? According to Kant our
mind has a priori categories (12 categories). One of
them is “causality”. So, this category constructs two or
more separated phenomena in an intellectual order.
 Then we know why the table is damage, i.e. because of
fire.
 On this level Kant justifies the validity of physics as
science, because the causality that is central on the
physics is the a priori category of our mind.
Verstand or Understanding
“All judgements therefore are functions of
unity among our representations, the
knowledge of an object being brought
about, not by an immediate
representation, but by a higher one,
comprehending , comprehending this and
several others, so that many possible
cognitions are collected into one.”
III.The Rational Level (or Vernunft)
 On this level our mind produces argument by
combining the statements of our intellect.
 The a priori of our mind is the three ideas of
pure reason, i.e. “world”, “soul” and “God”.
 The ideas are not objects of knowledge, but
principles in our mind that guarantee the unity of
events in the physical world (world), the
psychical world (soul) and in the all thing (God).
They are also not constitutive, but regulative.
Is the metaphysics possible as science?
 Kant answered with a no. Why? The ideas of God, world
and soul are not object of knowledge, but only unifying
principles of our mind. They are not empirical reality, but
transcendental principles by which we unify the physical
and psychical processes in a rational order.
 Also, the metaphysics is a form of knowledge that
doesn’t reflect the reality outside our mind. In the
metaphysics our mind reflects itself.
 Although the metaphysics is not valid as science, it is
according to Kant a possible form of knowledge. It is
not a science, but a form of knowledge.
 The metaphysical claims of God, world and soul have
not ground in the empirical world. They go beyond the
limits of our reason.