After reading the preface and introduction, we arrive at the extensive section of the book

known as the Transcendental Doctrine of Elements. This constitutes the majority of Kant's
Critique of Pure Reason. Kant aims to explore the various elements of human cognition. He
distinguishes between two key elements: intuition and understanding. In human terms,
intuition corresponds to sensibility, while understanding aligns with reason in a broadly
defined sense.

The first part of the Transcendental Doctrine of Elements is called the Transcendental
Aesthetic, which focuses on sensibility. The term 'aesthetic' is used here in its original sense,
relating to sensory experience. Following this, the Transcendental Logic discusses
understanding or reason. This section further bifurcates into the Transcendental Analytic,
covering the understanding proper, and the Transcendental Dialectic, addressing reason in a
narrower sense.

The objective of the Critique of Pure Reason is to understand human cognition, how it engages
with the world, and what this reveals about our a priori knowledge, metaphysics, and more.

For the Transcendental Aesthetic, I will rely exclusively on the second edition, the B version, as
it is more comprehensive than the A version. The B version opens with numbered paragraphs,
beginning with definitions that are crucial for the discussions that follow. Specifically, Kant
emphasizes two terms: "intuition" and "sensibility."

Intuition, or "Anschauung" in German, refers to the immediate manner in which an object is

given to us. It is the direct point of contact we have with specific, individual objects. Concepts,
on the other hand, do not provide us with this immediacy. When we think of cows, unicorns,
or trees, we are operating with concepts, not intuitions. Intuition is the means by which an
object affects our mind, granting us immediate awareness of it.

Sensibility, then, is the capacity to acquire representations through the way we are affected by
objects. It is the receptivity that allows these intuitions to occur. By focusing on these terms,
we establish the conceptual groundwork for understanding the subsequent sections on time
and space.

Kant posits that all thought aims at intuitions, indicating that cognition is not merely an
abstract or free-floating exercise. Rather, it seeks to relate directly to objects. In Kant's
framework, mere conceptualization is insufficient for coming into contact with the real world.
What is required for this contact is an intuition, a form of representation in which an object is
immediately given to us.

To clarify further, in intuition, we are in direct contact with an object. For humans, Kant
asserts, objects can only be given to us if they affect our minds in some way. This capacity for
being affected is what Kant terms "sensibility." In essence, sensibility enables us to have
sensations, which are activations of this capacity. For instance, perceiving a bust of Friedrich
Nietzsche through sensation places us in immediate contact with that specific object.

Kant also introduces the notion of "sensible intuition," which pertains specifically to humans.
He does, however, entertain the hypothetical existence of "intellectual intuition," wherein
simply thinking about an object might bring it into existence. While such intellectual intuition
might be the purview of a deity, human cognition operates strictly within the realm of sensible
intuition.
Progressing further into Kant's ideas, objects are given to us through sensibility, which
provides us with intuitions. These intuitions are then processed by the understanding, giving
rise to concepts. Kant's distinction here serves to underline the difference between intuitions,
which enable us to come into direct contact with individual objects, and concepts, which are
inherently general.

Concepts can apply to a multitude of objects, and thus lack the specificity that intuitions offer.
For example, the descriptor "bust of Nietzsche" could apply to numerous such busts, or even
potential ones. Additional characteristics, such as its color or place of purchase, are also
concepts that could apply to a wide array of objects. In sum, concepts do not allow us to grasp
an object in its full individuality.

Kant maintains that all thought ultimately relates to intuitions, particularly in humans, where
objects must be given through sensibility. While it's possible to think about things not given to
us, such as the 'thing-in-itself,' Kant demarcates this as an inferior form of thinking, devoid of
real cognition or knowledge expansion.

On sensation, Kant clarifies that it is the effect of an object on our capacity for representation,
and when this effect occurs, we have what is termed an 'empirical intuition.' This term could
potentially lead to confusion, as one may infer that all human intuitions are empirical since
they work through sensibility.

To counter this misconception, Kant distinguishes between 'sensation' and 'sensibility.'

Sensibility provides the form, while sensation fills in this form with matter. Kant introduces
'space and time' as the form of sensibility, suggesting that when an object affects us, it fills in
this pre-existing form with matter, giving rise to an empirical intuition.

However, it is also possible, according to Kant, to engage with the form itself (space and time)
without the matter, resulting in a 'pure intuition.' Thus, Kant offers two categories of intuition:
pure and empirical. Finally, Kant identifies the 'undetermined object' of an empirical intuition
as an 'appearance,' emphasizing yet another vital concept in his philosophical schema.

The term "appearance" in Kant's Critique of Pure Reason is easily misunderstood, especially if
conflated with the Cartesian or Lockean notion of "idea" as internal mental states. Such a
misreading would position Kant as a Cartesian skeptic, contradicting his aim to defeat such
skepticism. In Kant's framework, an "appearance" is not equivalent to an "idea." Rather, an
appearance refers to the "undetermined object of an empirical intuition."

In this context, "undetermined" suggests that the object has not yet been fully conceptualized.
Importantly, it is the object of the intuition, not the intuition itself, which constitutes the
appearance. The intuition is a mental state, while the appearance is what that mental state
puts us in contact with. For instance, if one has an intuition of a Nietzsche bust, the bust itself
is the "appearance," distinct from the mental state of having the intuition.

To address potential objections about illusion or dreaming, Kant would clarify that in such
cases, one does not have an intuition at all. According to him, an intuition necessarily puts one
in immediate contact with an object. Therefore, Kant's terminology is well-suited to distinguish
between veridical perceptions, which do put us in contact with objects, and non-veridical cases
like illusion or dreaming, where no such contact is established.

Kant's approach diverges significantly from Descartes, who begins with internal states as the
foundation for knowledge. Kant critiques this as a route to skepticism and posits that his own
transcendental idealism avoids the pitfalls of empirical idealism, in which perceptions and
illusions are indistinguishable because both are mere mental events.

In Kant's view, an "appearance" is not a Cartesian "idea." Rather, it is the object one
encounters through empirical intuition. In this framework, Kant is interested only in a priori
knowledge, not empirical phenomena. He addresses the pure, formal aspects of our sensibility
that await empirical content.

In the Transcendental Aesthetic, Kant focuses on space (and later, time) as a priori intuitions.
This is not about empirical reality but about the structural conditions that make empirical
reality knowable. He provides both metaphysical and transcendental expositions of space. The
former is deemed more important by many commentators and serves as the basis for Kant's
key contention that space is an a priori intuition.

Through the metaphysical exposition, Kant posits that space enables us to grasp individual
objects a priori. We don't need empirical experience to comprehend space; it is already a
precondition for our sensibility. This is foundational for Kant's transcendental idealism, which
suggests that space and time are human-centric frameworks not applicable to things-in-
themselves.

Kant argues that the a priori nature of space and time affirms his transcendental idealism,
distinctively separating it from other forms of skepticism and idealism. Understanding space
and time as a priori intuitions leads to the conclusion that they pertain only to the human
standpoint and do not govern things as they are in themselves.

Starting from a perspective similar to Descartes, who claims that one is primarily in touch with
their internal states, Kant takes a different route to address skepticism. Kant argues that only
by embracing transcendental idealism can one avert empirical idealism—a standpoint where
there's no way to differentiate an illusion from a perception of an object.

In his Critique of Pure Reason, Kant introduces the notion of "appearance," which is the object
of one's empirical intuition. Kant diverges from a Cartesian framework by stating that
appearances are not just mental events nor are they a veil behind which real physical objects
exist.

Kant then focuses on the "transcendental aesthetic," specifically on space and time. His
metaphysical exposition argues that space is an a priori intuition, serving as the basis for his
transcendental idealism. The brevity of this exposition has been subject to much commentary.
There are several possibilities for its concise nature: Kant might be summarizing the
arguments, deferring the full elaboration to later sections of the book, or he might actually
believe that it's fairly obvious that space is an a priori intuition.

The term "outer sense" in Kant's work refers to how we represent objects as independent of
our mind, not necessarily as spatially external to us. This is an important distinction and can be
illuminated further when juxtaposed with Cartesian skepticism, which questions the existence
of an "external world" independent of mental states.

By emphasizing that space is our form of "outer sense," Kant offers a non-tautological and
insightful point: To represent things as independent of our minds, we use the concept of
space. This stands in contrast to Cartesian skepticism, which casts doubt on the existence of a
world independent of our mental states. Here, "external" doesn't imply spatially outside of us
but rather signifies that which is independent of our mental processes.
Kant's claim that space is not something that applies to things in themselves, but only from the
human perspective, may initially appear as a hasty conclusion. There are a few ways to
interpret this brevity. One possibility is that Kant was rushing and thus left us to unearth the
real arguments in the text. Another explanation could be that Kant is summarizing arguments
he cannot fully make until later sections of the work. A third possibility, which I favor, is that
Kant deemed it self-evident that space is an a priori intuition, needing little argumentation.

To understand Kant's position, it's crucial to distinguish between two forms of "outer": the
"independent of my mental state" and "spatially outside of me." Kant suggests that when we
humans conceive of objects as independent of our mental state, we automatically conceive of
them as existing in space. This underscores the unique role of space in our cognitive
architecture.

External world skepticism, a form of Cartesian skepticism, concerns the existence of entities
independent of our mental states. However, we often equate these independent entities with
objects in space. This tendency confirms Kant's point: space is our way of understanding
"externality," or things that exist independently of us.

This singularity of space (and time) is key to understanding why Kant may have found it
unnecessary to elaborate extensively. Both space and time hold unparalleled positions in our
mental lives. Unlike color, for example, which is not essential for conceptualizing independent
existence, space (and time) serves a foundational role.

Kant outlines four arguments to defend his position. The first two focus on demonstrating the
a priori nature of space, while the latter two aim to show that space is an intuition. The first
argument states that space is not an empirical concept derived from outer experiences. For
sensations to be related to something external, they must be situated in a different place in
space from where I find myself, thus asserting that space is a priori.

In Kant's first argument, he is careful to avoid a certain pitfall: asserting that the concept of
space must be a priori simply because spatial representation requires some notion of space. To
make such an argument would be problematic, as it would render all concepts, including color,
a priori, contradicting Kant's view that colors are empirical.

Sebastian Gardner's interpretation of Kant offers an explanation. According to Gardner, Kant

argues that if the representation of space were empirical, it would have to come from the
experience of outer objects. However, this is impossible because the concept of "outer
objects" already presupposes the representation of space. Therefore, the representation of
space must be a priori. One criticism of this reading is that it leaves open the possibility that
both the concept of outer objects and the representation of space could be acquired
simultaneously through experience.

An alternative perspective draws a distinction between spatial relations and space itself.
Imagine acquiring experiences of color: red, green, and blue-green. As one gains more
experiences, one could develop a sophisticated understanding of color, a kind of "color space,"
through empirical experience. This story of empirical acquisition seems entirely plausible for
color but does not extend to space.

Kant's argument hinges on the unique nature of space. Unlike colors, which could plausibly be
organized into some sort of relational structure post-experience, the representation of space
must already underlie our ability to even perceive outer objects as external and in relation to
one another. Therefore, space serves as the necessary foundation for experiencing objects as
"outer," reinforcing its a priori status.

Kant posits that space is not empirically derived but a necessary a priori representation that
conditions all external perceptions. Unlike empirical concepts such as color, which may emerge
and become sophisticated through experience, the representation of space must precede any
spatial relations or experiences. For example, to conceive one object as 'to the left' of another
necessitates an antecedent conceptual framework of space itself; it is the canvas upon which
any notions of spatial relations can be meaningfully inscribed. Therefore, individual spatial
relations, like 'left of' or 'bigger than,' require a pre-existing grasp of space as a whole. They do
not build up to form space; rather, they are predicated upon it.

Kant further argues for an asymmetry between space and objects within space. He asserts that
while it is conceivable to think of empty space without objects, it is inconceivable to think of
objects without a space that contains them. Space is the 'form' that awaits its empirical
'matter,' which are the objects and their relations we encounter through sensation. Thus, Kant
dismisses any relational theories of space that posit space as a derivative of objects and their
relations. The representation of space is an a priori condition, not contingent on external
realities.

This brings us to the nature of space within Kant's philosophical framework. It's neither a
general concept nor an empirical intuition but rather an a priori form of intuition. It conditions
the possibility of any external experience and sets the stage for the 'matter'—the empirical
data—to make sense. Subsequent arguments will focus on elucidating the ontological status of
space as either concept or intuition, aiming to show it as the latter.

Three: Space is not a discursive, or as said, general concept of relations of things in general,
but a pure intuition. Kant posits it's not a concept but an intuition. Why? One can only
represent a single space. Multiple spaces are understood as parts of one unique space, not as
components that form it. Space is essentially single; the manifold in it rests merely on
limitations. This leads Kant to assert that space is an a priori intuition, not an empirical
concept. It forms the basis of geometrical principles derived a priori with apodictic certainty.

Four: Space is represented as an infinite given magnitude. Unlike a concept, which can be
thought of as a common mark contained in an infinite set of different possible representations,
space is thought to contain an infinite set of representations within itself. All parts of space,
even to infinity, are simultaneous.

In the Kantian framework, space serves as the a priori condition for any possible experience
and is represented not as a concept but as a unique, infinite intuition. Kant argues against the
idea that space could be derived from empirical experience or that it functions like a general
concept. Rather, it is an individual thing that we find ourselves inherently placed within, which
becomes the foundational form waiting for empirical matter.

The original representation of space is not a concept but an a priori intuition. Kant
distinguishes the nature of space from being either finite or infinite, indicating that space is
better described as unbounded. Within this unbounded framework, space can be partitioned
into smaller, limitless subspace regions. This attribute sets it apart from concepts, which can be
general but not infinitely divisible.
Kant argues that concepts can also be general, covering an infinite number of particular
instances, but they can never contain an infinite set of representations within themselves. For
example, the concept of a tree encompasses infinitely many specific trees but does not include
an infinite array of sub-concepts or characteristics. In contrast, space consists of an endless
number of subspaces. Further, while concepts can have components, these are finitely
bounded. For instance, the concept of a factory could comprise elements like 'building,'
'industrial scale,' and 'production,' but these are finite and countable components.

According to Kant, if space were a concept, it would necessarily be finite or limitable. Since it is
neither, it leans more towards being an intuition. Things given in intuition, like a statue with
intricate details, can theoretically contain infinite parts without issue, making space more
analogous to an intuition than a concept.

Kant contends that space, as an a priori intuition, serves as the substrate within which all our
external experiences are framed. We comprehend it immediately and in its entirety, despite its
limitless nature. This feature suggests that space is a form of sensibility not originating from
empirical sensations but serving as a precondition for such experiences.

In the metaphysical exposition, Kant has established two key points: space is a priori and an
intuition. He occasionally conflates 'space' with the 'representation of space,' arguing that
ultimately, they are indistinguishable. The conclusion he draws is that space does not
represent any inherent properties or relational attributes of things in themselves. It serves
rather as a framework within which we understand objects and their relations but does not
correspond to any actual qualities they possess in and of themselves.

In Kant's metaphysical exposition, he posits that space is both a priori and an intuition.
Contrary to the notion that space is a concept, Kant argues that it is more akin to an intuition
because it contains infinitely many, or at least unlimitedly many, subspaces. This diverges from
concepts, which can contain finitely many representations or parts. For example, the concept
of a "tree" can manifest in infinitely many individual trees, but these trees are not parts of the
concept; they are examples under it. This distinction underlines Kant's assertion that the
representation of space must be an intuition, not a concept.

Shifting his focus to "things in themselves"—a concept whose interpretation is hotly contested
among Kantian scholars—Kant asserts that space bears no properties of things in themselves.
It means that if one abstracts away from all subjective conditions of intuition, space would lose
its applicability. This is elaborated upon through the concept of "the human standpoint," which
implies that space's applicability is confined to how things are given to human intuition. Hence,
according to Kant, the transcendental idealism posits that space is only relevant when
considering things from the human standpoint.

The concept of "things in themselves" is not to be construed as a realm unreachable by human

intuition but rather as what remains when one abstracts from the subjective conditions of
intuition. Kant's argument suggests that attempts to understand things beyond the human
standpoint are mostly futile, for space, a key frame of reference, becomes inapplicable. Thus,
Kant's core message is that space is fundamentally an a priori intuition that gains its
meaningfulness within the parameters of human experience.

Kant distinguishes between things as they appear to us and things in themselves. When
considered from a non-human or perhaps god-like standpoint, spatial characteristics cease to
be applicable. The concept of space becomes meaningless once we move beyond our
subjective conditions of intuition.

Kant believes that space is an a priori intuition, a fundamental structure of our capacity to be
affected by objects. It is the form that is ready to be filled by the matter of sensation. Given
this role of space and time as subjective conditions of intuition, when one abstracts from these
conditions, one essentially abstracts from space and time themselves. Consequently, it
becomes nonsensical to apply the concepts of space and time to things in themselves.

Kant doesn't delve into complex arguments to substantiate the transcendental ideality of
space; he finds it an evident conclusion given its a priori nature. He asserts that space pertains
only to the human standpoint and conditions the appearances of things, but not the things in
themselves. Thus, it's a subjective condition that makes outer intuition possible for us, but not
necessarily for other thinking beings. We cannot assert that our conditions of intuition are
universally applicable, because we cannot know whether other beings share the same form of
intuition as us.

Kant asserts that space and time are conditions for how things are given to us, not for the
things in themselves. This view contradicts the "neglected alternative," the notion that things
in themselves might also exist in space and time. According to Kant, this alternative lacks
coherence, as space and time are forms of intuition specific to our subjective conditions.
Hence, they cannot be applied to things outside of those conditions.

In Kant's framework, space and time are "transcendentally ideal," meaning they pertain solely
to the manner in which things appear to us. They are not "transcendentally real," i.e., they do
not apply to things independent of their givenness to us. This renders them empirically real but
transcendentally ideal.

Kant elucidates the objective validity or "reality" of space and time in relation to all possible
outer experiences. They are unequivocally applicable to any object given to us; hence they
have empirical reality. But their transcendental ideality comes into play when we consider
things apart from our subjective conditions. In such instances, space and time lose their
applicability.

Kant argues that once we mentally abstract from the subjective conditions under which things
are given to us—space and time—we can no longer meaningfully apply these categories.
Therefore, they are transcendentally ideal and are only relevant to appearances, not to things
as they are independently of us.

The question of whether we should adopt a human or non-human standpoint remains open.
While a transcendental standpoint focuses on the structure of human cognition, a
transcendent standpoint aims to understand reality independently of human perception. If we
consider the transcendent viewpoint as true, then space and time appear second-rate. Yet,
Kant provides no justification for privileging this transcendent perspective.

Thus, a more productive reading of Kant suggests we set aside the idea of a transcendent
viewpoint. We only have access to the human standpoint, and to imply it is second-rate is
untenable. In Kant's system, the empirical reality of space and time isn't a lesser form of
reality; it's simply reality. Transcendental ideality is a conclusion we draw in philosophical
inquiry, not a judgment on the quality of empirical reality.
Kant later argues that those who seek to adopt a transcendent standpoint—believing in the
transcendental reality of space and time—risk becoming empirical idealists, claiming that our
sensory world is illusory, which leads to skepticism. Kant aims to prevent this outcome,
focusing instead on empirical reality and transcendental ideality as the domains of human
cognition.