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Nineteenth Century Philosophy – Phil. 3122
Lecture Notes 2 – Critique of Pure Reason
Preface to the first edition of the Critique, 1781
Kant’s Critique of Pure Reason sanctions the beginning of 19th century philosophy since all the
philosophers after Kant will confront themselves – positively or negatively – with Kant’s work. The
Critique appears in the first edition in 1781 and in the second edition in 1787. We are at the threshold of the
French Revolution (1789), at the beginning of a new historical and political order. As Kant makes clear in
the 1787 Preface, the Critique inaugurates a “revolution” in philosophical thinking, a revolution in the way
of doing philosophy. We’ll concentrate on seeing what this revolution consists in.
Metaphysics - Pay very close attention to the first page of the 1781 Preface. At stake is
“metaphysics.” Kant positions his work in relation to metaphysics. He implicitly distinguishes two concepts
of metaphysics.
1. Metaphysics is, first, “natural” metaphysics, namely, what Kant calls the “peculiar fate” of human
reason. It is the natural tendency of our human reason to ask questions that go “beyond” (meta=beyond)
experience. Metaphysical questions are questions that start on the ground of experience and progressively
go higher and higher in the quest for a “why” that cannot be observed and can never be the ultimate and
final one. Notice that there is nothing wrong in this striving for the ultimate “why” of things. It is the
inevitable tendency or nature of our human reason to do so. The problem is in the following: in trying to
answer metaphysical questions, reason uses the principles and concepts that it generally uses in the world
of experience (cause and effects, objects and subjects, etc.). This gives raise to contradictions, to the
illusion that reason is able to solve unsolvable problems.
2. Metaphysics is, second, historical metaphysics, namely, the discipline that philosophers have
cultivated since Plato and Aristotle. This is what Kant calls the “queen of all sciences.” In the second page
of the Critique, Kant sketches out a “history of metaphysics.” Since metaphysics occupies itself with
unsolvable problems (per 1.), “skeptics” have soon questioned the theories that philosophers have come up
with. These theories, not being based on experience, cannot be proven. Skepticism is the denial that truth
exists. This is a deadly position for reason; it is the end of philosophy. The historical fight between
“dogmatic” metaphysics and “skepticism” gives raise to what Kant calls “indifferentism”- namely, to the
position that nothing really matters in philosophy, since no one seems to be able to reach the truth.
Kant wants to save philosophy from “dogmatism” (the idea that there are things accepted as such, like
“dogmas”: this is obvious, think of What is Enlightenment?) as well as from skepticism and indifferentism.
The Critique will prove that there is “truth” – that truth is based on experience; this is science. But what
about metaphysics? The question of this work is: is metaphysics as science possible? Is metaphysical truth
possible?
Critique - The Critique is the project of reason’s “self-knowledge.” In answering that question,
human reason is ultimately called to examine itself, to examine how far its quest for knowledge goes. Can
reason’s knowledge stretch up to metaphysical knowledge or is metaphysical knowledge illusory? Kant’s
question, then, is “how can reason know independently of all experience”? In this quest reason is “pure,”
i.e., not mixed with experience. The notion of “a priori” (p. 5) is connected to this. Pure knowledge is
knowledge that comes before or is “prior” to experience. This is the question: is there any knowledge prior
to experience?
The self-criticism of reason that is the book Critique of Pure Reason is inscribed, by Kant, is the “age
of criticism” (see Footnote p. 3). You should connect this with What is Enlightenment? The Enlightenment
is the age of criticism, the age that culminates in and produces the French Revolution.
These are the fundamental points I want you to concentrate on in the Preface to the first edition.
Preface to the second edition of the Critique, 1787
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In this Preface as well, Kant starts with the issue of metaphysics and with the questions of whether
metaphysics can be a science. The argument, however, is different this time. Now Kant compares
metaphysics to all other sciences, namely, logic, mathematics, and physics. He starts by sketching out a
history of the sciences. How do these sciences get to acquire the status of “sciences,” i.e., their “truth” –
universal and necessary and indisputable?
Logic – Logic has a peculiar history since, Kant explains, logic has been a “science” from the very
beginning and has change almost nothing in it.
Mathematics and Physics – The history of these disciplines is important. Kant’s claim is that a
bunch of empirical observations (physics) or mind games (mathematics) has turned into a science only once
a “revolution” in the method of thinking has taken place, namely, once a strong “paradigm change” or a
radical change in the way of thinking about problems in the field has taken place. What is this revolution?
In short, it is the idea that truth can be achieved by the mind’s “construction” of its object.
Important is the paragraph on page 19/Bxii (in margin): “The true method […] etc.” We are talking
about Thales’ discovery of the law of the triangle. The point is this: there is no already made triangle out
there that the mind is supposed to inspect or observe in order to read out the properties of the figure. The
triangle is constructed or made by the mind itself according to a law of construction (concept of
triangle=figure with three angles). We have to make the triangle, draw it on the board or in our mind
according to a concept in order to discover what a triangle is.
The case of physics (p. 20/Bxiii ff.) is analogous. At stake is the concept of “experiment.” An
experiment is a mental construction; it is a question that reason poses to nature in order to get a specific
answer. Truth is not the result of random search; it is the result of a targeted questioning of nature. Physics
becomes science when it understands this. The important claim (underline it!) is: “reason has insight only
into that which it produces after a plan of its own” (Bxiii).
Can metaphysics become a science? - Now the question Kant asks is this: can the method of
construction that led mathematics and physics to the status of science be applied to metaphysics so that
metaphysics too can become a science? This is the question proposed and investigated by the Critique.
How would the change of philosophical method look like, in this case?
The Copernican Revolution in philosophy – is what the Critique proposes as the revolution in the
method of doing philosophy (pp. 22-23/B xvii-xix). These are difficult pages but very important, please
spend time on them. What is the revolution achieved by the astronomer Copernicus? It is the hypothesis
(pay attention: it is an hypothesis not an observation!) of a change of point of view: if we assume that the
earth is at the center, astronomy goes nowhere; but if we assume that the sun is at the center and the earth
revolves around it, then astronomy progresses in its pursuit of truth. Let us apply this same hypothetical
change of perspective to philosophy. Up until Kant’s time the assumption in the theory of knowledge was
that the “object” to be known was a fixed independent given and the subject’s mind (or the knower) had to
go out and grasp the truth of the object. Let’s invert this. Kant proposes to assume the subject’s mind as the
center and endow the mind of the power of constructing its object. Truth, in this case, is the convergence of
subject and object but the creative power lies in the subject (recall physics and the question that reason
poses to nature which orients the search for truth).
Experience – What follows from this change of method is a new concept of “experience.” Experience
is a construction of the mind meeting reality (the object). Experience is a complex affair which originates in
the mind and in its powers. When Kant speaks of “a priori” he means the powers that the mind puts into its
construction of experience. These powers precede experience (thence they are “prior” to it) because they
are the conditions of possibility of experience. If we did not have the mental powers we have, experience
would be impossible (example: if we did not have eyes, i.e., the power to see, visual experience would be
impossible).
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There is a lot more in the second Preface, but we’ll stop here. Some other points we shall explore in
the Introduction.