Kant’s Theory of Knowledge: Judgments, Categories, and A Priori Forms
Theory of Knowledge
To develop his Theory of Knowledge, Kant takes as its model the physics and mathematics of Newton, who had succeeded in expressing the laws of nature in ways accepted by all scientists. This did not occur with Metaphysics, which was drifting, and where each had its own theories. Kant calls the science of Newton the fact of pure reason. Considered a fact, a reality, and analyzing it, he proposed to find out how to use reason to get real knowledge.
Kinds of Trials
Kant said that the sciences are composed of judgments, which are factual statements about something. They are classified according to two different criteria: relationship between subject and predicate, and the relationship between opinion and experience.
According to the First Criterion:
- Analytical: The information given by the predicate is contained in the subject. They are necessary (cannot be false) and universal, or are based on the principle of non-contradiction, and what they claim is valid for all individuals of a class. They do not extend the knowledge of reality. Example: A triangle has three angles.
- Synthetic: Constructed through a synthesis between a subject and a predicate which in principle are not interrelated (The Earth orbits the Sun). Such trials extend knowledge of reality, but their truth is not necessary.
According to the Second Criterion:
- A Priori Judgments: Their truth is not dependent on the completion of an experience, and therefore are universal and necessary.
- A Posteriori Judgments: Their truth requires experimental verification. They are contingent because their opposites are not impossible, and in general, are not universal.
A Priori Synthetic Judgments
If the physical and mathematical sciences were only formed by analytic judgments, they would be useless since they reduce to simple repetition. And if consisting only of synthetic judgments, they would lack universal validity. Therefore, according to Kant, they must be of a third type of judgment, which are universal and necessary (as analytical judgments) and, moreover, increase the knowledge of things, so they must come from experience. Kant calls these synthetic a priori judgments. They are specific to science and he lays their foundations in his work Critique of Pure Reason, in which he expounds his theory of knowledge.
Synthetic A Priori Judgments in Mathematics
For Kant, geometry and arithmetic are the foundations of mathematics. Geometry deals with properties of space, and arithmetic is based on the properties of natural numbers, which constitute a series, so its ultimate foundation is time. As space and time are a priori forms, valid in any trial, arithmetic and geometry are also a priori. Moreover, both express properties that are not contained in the notions of space or time, so their judgments are synthetic.
Parts of the Critique of Pure Reason
It is divided into two parts: the Transcendental Aesthetic and Transcendental Logic, and the latter in turn into the Transcendental Analytic and Transcendental Dialectic. In each of the three parts, it establishes how synthetic a priori judgments are possible in mathematics, physics, and metaphysics, respectively.
Elements of Knowledge
According to Kant, there are two sources of knowledge: sensitivity and understanding.
- Sensitivity is the ability to have feelings. It is merely receptive, as it merely receives impressions from abroad: colors, sounds, etc. It corresponds to what Hume called impressions of sensation.
- Understanding is active and occurs spontaneously with certain concepts and ideas derived from experience, such as substance, existence, cause, etc.
Transcendental Aesthetic
Feeling, Intuition, and Sensation
A phenomenon is an effect that an object produces on our sensibilities. When the feeling is captured by the subject, it becomes an immediate knowledge, which Kant called sensible intuition (or empirical). The object captured in sensuous intuition, what causes it, is called the phenomenon (which in Greek means what appears). Therefore, what the subject captures is not the thing itself but a manifestation of it.
Matter and Form of Phenomena
- Matter is the content of sensation. It originates from the object known, and as experience, it is a posteriori.
- Form is the way that the subject captures matter. Therefore, it is not of the known object, but of the knowing subject. It is therefore a priori, prior to all experience.
Space and Time: A Priori Forms
For Kant, space and time are not realities in themselves, but the manner in which our sensitivity orders the impressions we receive. They are structures of the subject (such as molds) that make it possible to capture objects. Hence we call them a priori forms of sensibility. “They’re ways” means they are not private sense impressions, but how we perceive them. “A priori” means they do not come from experience, but precede it, as prerequisites for possible experience.
Pure Intuitions
Kant also considers space and time pure intuitions.
- Intuitions, not concepts of the understanding, as it applies to a multiplicity of individuals, but space and time are only one; there is not a plurality of spaces and times, but a unique and single time that flows unceasingly.
- Pure, for lack of subject matter, empirical content, since it does not come from reality.