Kant’s philosophy- english language
Kant gives birth to a new philosophical current: the Criticism, which consists in sifting, establishing
THE LIMITS, THE POSSIBILITIES AND THE VALIDITY of human reason, in the gnoseological and
practical field (its areas of relevance). Kant belongs to the Age of Enlightenment, but exceeds it
when he makes reason the subject and object of philosophical inquiry: reason is called before the
tribunal of reason, because it is both the one who performs the investigation, and the one who is
the object of this investigation.
More specifically, we define Kant’s philosophy as the HERMENEUTICS OF THE FINITE: human
reason as such is finite, but it is precisely in the finite, in the limits, that it reaches a certain
knowledge; if we transcend these limits, or experience, we meet the so-called EMPTY CONCEPTS,
proper to metaphysics. Metaphysics for Kant is a natural disposition in man, because he by nature
tends to transcend the experience, and try to know God, the soul, and the world (objects of
metaphysics), but transcending in this way the experience, do not reach any certain knowledge.
Who provides us with certain knowledge is science, which is based for Kant on the SYNTHETIC
JUDGES A PRIORI. There are 3 types of judgments:
Analytical a priori judgments: analytical= they are not based on experience, so they are
universal; a priori= they come before experience. The strength of these judgments is that
they are universal, but because they are a priori they do not increase my knowledge, so
science cannot be based on these judgments.
Synthetic a posteriori judgment: synthetic= they increase my knowledge; a posteriori=
they start exclusively from experience. Weak point is that they don’t have that character of
universality, but they do increase my knowledge.
Synthetic a priori judgments: they increase my knowledge, and do not rely exclusively on
experience, but experience is accompanied by the use of the subject’s a priori mental
For Kant, science is the union of MATTER and FORM:
-matter is the chaotic multiform whole that comes from experience, and therefore needs to be
– form is the a priori element, which coincides with those a priori mental forms, which give order
to the material coming from experience. These mental forms are something innate in each of us,
which come into play only in contact with experience. Therefore, if we transcend experience, the a
priori mental forms are not activated and thus we do not arrive at knowledge.
Kant develops a COPERNICAN REVOLUTION in the field of gnoseology (change of perspective): if
up to that moment, the most widespread gnoseological perspective was that of gnoseological
realism, for which it is the subject that must submit to the object to be known, with Kant it is the
object that must submit to the subject, which with its a priori mental forms orders and filters it. I,
therefore, know reality as it appears to me.
PHENOMENON AND NOUMENON
In Kant, the most important dualism is that between phenomenon and noumenon.
The phenomenon (phainomai= what appears to me) is the certain object of my knowledge, it is
the phenomenon of which I experience. The phenomenon is what is FOR ME, because what I know
depends on my mental structures.
The noumenon (nus= intellect) is “the object of a hypothetical divine intellect”; it is the logical
correlate of “for me”, that is “THE IN ITSELF”. I cannot know the noumenon, because it transcends
experience. The noumenon is thinkable, but not knowable (scope of metaphysics).
THE CRITIQUE OF PURE REASON
In this work, Kant answers the questions: 1) How is pure physics possible? 2)How is pure
mathematics possible? 3)Is metaphysics as a science possible? 4)How is metaphysics as a natural
The cognitive path starts from SENSITIVITY, studied with its a priori mental forms by
transcendental aesthetics; after that, INTELLECT takes over, studied with its a priori mental forms
by transcendental logic, divided in its turn between transcendental analytics, which studies the
intellect, and transcendental dialectics, which studies reason.
Intellect and reason are separated, not because they are two different faculties, but because
reason is nothing more than an intellect that has transcended the limits of experience.
It is important to focus on the term TRANSCENDENTAL, which is different from transcendental:
transcendental means “to study the a priori formal element”, which makes knowledge possible.
Sensibility is the first faculty devoted to knowledge. Sensibility INTUISES the material coming from
experience, in the form of impressions, all disordered. It intuits through its pure intuitions, which
are SPACE and TIME, without which I would not intuit any empirical datum: I intuit spacetemporalizing the empirical datum.
Space is “the form of the external sense”, thanks to which I arrange things one next to the other;
Time is “the form of the internal sense,” thanks to which I arrange things one after the other, in
For Kant, time has primacy over space: 1) because I cannot perceive one thing next to another, if I
have not first perceived them in succession one after the other; 2) because not everything is in
space (mood, sensation…), while everything is in time.
Geometry is based on space (“a straight line is the shortest line between two points” is based on a
spatial intuition); mathematics is based on time (7+5=12 summing means grasping the succession
of numbers). This part of the work answers the question 1) How is pure mathematics possible?
Studies the role the intellect plays in the cognitive journey.
We have seen that sensibility intuits the empirical datum through space and time: if we stopped at
the level of sensibility, we would still have to deal with a disordered and chaotic material, because
it is true that through space and time sensibility gives to the empirical datum a first order, but it is
still not enough. Therefore, it is necessary the intervention of concepts, which are the products of
intellectual activity, which give a final order to the empirical datum. But beware, concepts without
intuitions “are empty”, because the intellect must necessarily operate on the empirical material,
because if I try to apply pure concepts going beyond the phenomenal, they become empty
The activity of the intellect is to subsume, unify, synthesize, the various representations under a
single representation; thus uniting the various intuitions of sensibility under a single concept. The
intellect does this through its a priori mental forms which are the 12 CATEGORIES (Aristotle: there
were 10 and they were the modes of being of being). In Kant, the categories have exclusively a
gnoseological function: they are not the modes through which I reflect reality, but through them I
order reality, I give form to reality. To draw up the table of categories, Kant makes use of that of
judgments (to know=judge and to know=conceptualize). There are 4 categories: quantity, quality,
relation and modality.
The ones that interest us are only the category of SUBSTANCE (modality) and CAUSALITY
➢ SUBSTANCE: for Kant the substance has no ontological foundation, but it is a pure concept
of the intellect, so the substance is something that I give to the object, in virtue of my
mental forms. The substance exists because I am the one who gives it to the empirical
object, so it does not have an objective basis, but subjective (note the Copernican
➢ CAUSALITY: for Kant causality is no longer the objective characteristic of a phenomenon,
but it is an order that I give to the phenomenon (overcoming physical skepticism Hume).
Causality is a pure concept of intellect, causality is no longer based on habit (Hume) and it
is not an objective order of the world, but it is the order that I give to the world, I
understood as humanity because the a priori mental forms, as innate, are common to all
men, so anyone in front of two phenomena, will grasp their causal relationship.
The term deduction has a meaning called “forensic juridical”: in this part of the analytic, Kant
wants to “justify by law what is a factual claim”; in other words, he tries to legitimize the use of
categories, because he wonders: but who guarantees me that nature, which I did not create, is
actually filtered by my mental forms? Who can guarantee me that that causality is not actually
proper to the object, but that it is I who confer it by virtue of my categories?
However, one thing must be emphasized: Kant does not make a deduction of space and time,
because I cannot grasp the datum except through space and time, which therefore precede
experience, because otherwise I could not know anything.
If I do not justify the use of categories, the risk is that there is no correspondence between what I
think and what happens in reality. I have to be sure that nature actually allows itself to be filtered
We have said that the activity of the intellect is to subsume, to synthesize the various intuitions
under a single representation. More specifically, this activity is carried out by a SYNTHETIC UNIT,
by a unifying mental center, which takes the name of “I THINK”. The “I think” is what performs the
extreme synthesis, the synthesis of the synthesis; it comes before the categories, because the “I
think” subsumes, unifies through the categories, thus giving life to all our judgments, which
therefore must necessarily refer to the “I think”, because if there were no “I think” these
judgments would not exist. The “I think” becomes TRANSCENDENTAL APPRECIATION, I mean by
apperception the awareness of thinking that particular judgment; it is not enough that I think that
judgment, but that I think of thinking that judgment. The I think refers every synthesis to itself; the
I think refers all judgments to me who thinks them. The “I think” is the supreme principle of our
knowledge: reality is such because I think of it in this way, the “I think” gives order to nature, an
order which will not change because there is an “I think” which will always see a causal
relationship between two phenomena. This synthetic unity is only form, it is not a substance
identifiable with a soul, a psyche…; it is common to all men.
With the “I think”, Kant criticizes idealism, in particular the “problematic idealism” of Descartes,
with which the intuition of the “I” occurs before the awareness of the existence of a world outside
me. With Kant, on the contrary, the “I think” comes into play only if there is a world outside me,
also because otherwise he would have nothing to work on, nothing on which to drop the
This is the part, always inside the analytic, that looks more concretely at the application of the
categories, that is, it provides us with the rules by which we apply the categories. In schematism a
new faculty is introduced: the productive imagination (different from the Aristotelian
“reproductive” one, which reproduces a perception in the form of an image), which is located
halfway between two faculties that are different by nature, namely the sensibility, which operates
through the senses and enjoys immediacy, and the intellect, which instead moves in a discursive
way and elaborates concepts. The productive imagination produces something new, namely the
schema, which is a kind of rule that guarantees us the correct application of the categories on the
empirical material. So, this means that: the imagination operates on the material intuited by the
sensibility, and then passes it to the intellect. Beware, however: the imagination intuits the data of
sensibility not according to general time, but according to a specific time. The transcendental
schema is therefore a sort of category set in time, because time conditions the objects and
therefore through the schema, the intellect, by conditioning time, also conditions the objects, thus
ensuring that the objects are filtered and ordered correctly.
There is a schema for each category, but we are going to see what rules must be followed for the
correct application of the category of substance and causality.
When do I apply the category of substance? Whenever the productive imagination intuits, in a
given time, the permanence of the empirical datum; at this point, we unify all intuitions under the
category of substance.
When is it that I apply the category of causality? Whenever the productive imagination intuits that
there is a succession between two intuitions, and then the intellect then applies the category of
The path of knowledge is concluded. At this point, we see how experience, which is the starting
point of knowledge, has now become phenomenal order, thanks to the joint work of sensibility,
productive imagination, and intellect.
Experience as phenomenal order is the point of arrival, beyond which we know that knowledge
cannot proceed. Venturing beyond the limit, we enter the realm of metaphysics, and thus the last
part of the work, which takes the name of transcendental dialectics.
“Dialectics” is resumed in the Aristotelian meaning: for Aristotle, dialectics were wrong reasoning,
which started from probable premises that therefore did not guarantee certain knowledge. This
negative meaning is taken up by Kant, with whom specifically “dialectics” has the meaning of
“logic of appearance”: Kant wants to expose the false cognitive claims of reason, which
proceeding beyond the limit of experience produces ideas, or empty concepts. In particular, these
ideas are that of soul, world and God:
Soul=totality of internal phenomena
World=totality of external phenomena
God= totality of external and internal phenomena.
On these 3 ideas are founded 3 alleged sciences, which are unmasked by Kant.
Soul→ RATIONAL PSYCHOLOGY: this science is based on the error that takes the name of
paralogism, that is a wrong reasoning of reason. The error lies in having applied the category of
substance to the “I think”, thus committing two errors: 1) the “I think” cannot be at the same time
subject of the categories and then also object of application of the categories 2) the “I think” has
an exclusively formal value, it is not substance. He is not saying that there is no soul, he is saying
that it is not possible for us to know it, we can only think it, but we cannot be sure that it exists.
World→ RATIONAL COSMOLOGY: this science has as its object the world, understood as the
totality of phenomena, and the fact that it has to do with the totality makes us understand how
we are outside the experience, which instead has always to do with the particular. This science
makes mistakes called antinomies, that is antithetical pairs formed by thesis and antithesis, of
which, however, we cannot say what is true and what is false. It offers us 4 antinomies, and from
these antinomies emerges another Kantian dualism, taken up more specifically in the moral field,
which is that between necessity (regulates the phenomenal world) and freedom: is man only
phenomenon, or is he also free?
God→ RATIONAL THEOLOGY: God is a noumenal concept, of which therefore we cannot have a
rational demonstration. He reckons with the different proofs on the existence of God:
ONTOLOGICAL PROOF A PRIORI: starts from the definition of God, as the one “of whom
nothing greater can be thought” (Anselm of Aosta) and as “the most perfect being”
(Descartes). The ontological proof tends to affirm the existence of God from its definition:
God is the most perfect being that exists, then if he is perfect, he must necessarily exist,
because if he did not exist this would affect his perfect being, and therefore we would no
longer speak of God. This proof makes a quantum leap from the logical to the ontological
plane, existence is something that can only be ascertained in relation to something that I
perceive as permanent in a given time. Moreover, says Kant, the other limitation of this
proof is that it is contradictory, because the existence of God that it wants to prove is
already contained in the very definition of God.
COSMOLOGICAL PROOF: it is an a posteriori proof, that is, it starts from what is in front of
me, nature, to go up to what is in itself. In this regard, Thomas Aquinas develops “the 5
Ways”, of which we have focused on what is called “ex contigenzia mundi”: Thomas starts
from the observation that everything in nature is contingent, meaning by contingent
something that can be and not be, something that is subject to birth and death. Everything
that exists in nature, being contingent, cannot explain itself or be explained by another
contingent, but needs something necessary, which needs nothing else to be explained. The
mistake that this proof makes is to apply the category of causality in the transphenomenal, because to explain the contingent I use another contingent, but then I realize
that this contingent does not explain the previous one, and I proceed in this way until I
hypothesize the existence of an incaused cause that is the cause of the whole, but by the
time I get here, I have already passed the experience. Then, Kant says that this proof makes
the mistake of the first one, because I said that there is this incaused cause that is
necessary (therefore perfect), and that therefore it must exist, because otherwise it would
not be perfect and necessary.
PHYSICAL TELEOLOGICAL PROOF: it is based on the vision of the world as a big clock, which
however needs a watchmaker to be explained. This reason has made the same mistakes as
the other two: to explain the order of nature, I do not have to go outside nature from a
gnoseological point of view, because the order, the harmony, the laws, are immanent in
nature itself. Instead, I went further, assuming a creator, and therefore one that must
necessarily exist, etc…
THE FUNCTION OF IDEAS
At this point, Kant gives us what is the function of ideas, which are inevitably produced by reason,
because by nature man tends to think in terms of soul, world and God, so these ideas must have a
function. We make a “transcendental” use of ideas when we pretend that these ideas correspond
to something; instead I must make a “transcendental” use of them, which means making a
REGULATIVE use of them: ideas must be placed at the service of the intellect, because if in the
cognitive process I place these ideas in the background, they stimulate the intellect, making it
expand its knowledge; they are a stimulus to expand my knowledge. Of these ideas, therefore, we
must make a regulative use, immanent, heuristic (eureca=discovery), because they allow, with this
use, the intellect to expand even more the panorama of its knowledge (attention, it is not
intended that he knows these ideas, because they remain unknowable being something transphenomenal, but they are a stimulus for him to expand his knowledge).