Kant’s Theory of Knowledge: A Critique of Pure Reason
Kant’s Theory of Knowledge and Reality (Critique of Pure Reason)
1. Human Knowledge and Representation
Human knowledge is finite and limited. We do not know things directly as they are in themselves (that is the privilege of an infinite mind). Instead, we know them through representations.
2. Knowledge as a Process
Human knowledge is a process of receiving and interpreting information, not a creation of it.
3. The Role of Sensitivity
Sensitivity is the capacity to be affected by objects and receive representations of them. Human knowledge begins with experience or sensation (perception), which is the only direct knowledge we can acquire. Sensitivity is passive and directly affected by objects, involving the reception of sensations that form the basis of knowledge.
4. The A Priori and A Posteriori
Information received through experience (a posteriori) is always particular, multiple, and diverse. Universality is not given through experience but comes from the subjective cognitive structure itself, which is a priori.
5. Subjective Forms of Knowing
Information received through experience is processed through subjective forms of knowing. These are the a priori forms of subjectivity, the conditions and ways in which we understand reality.
6. Synthesis of A Priori and A Posteriori
Knowledge is a synthesis of two elements:
- A posteriori conditions: information received through sensitivity.
- A priori conditions: mental structures that shape how we perceive, understand, and interpret reality. These include space, time, and categories like substance, accident, cause, effect, unity, and reality.
According to Kant, sensations are perceived in space and time, which are a priori forms of understanding. We use these forms to create concepts and judgments about reality. These perceived objects are called phenomena.
7. Limits of Knowledge and the Noumenal Realm
Reality (noumena) is not fully captured by our senses. There are aspects of reality that may be beyond our capacity to know. What we know is not reality itself but phenomena, the objects of our experience. The noumenal realm, the reality beyond our experience, transcends our knowledge.
8. Avoiding Metaphysical Errors
We must not confuse our limited perspective with reality itself. When making assumptions and drawing conclusions, we should not overstep the boundaries of human knowledge and experience. What is valid within these limits may not hold true outside of them. Ignoring this limitation leads to metaphysical errors.
9. Limits of Rational Knowledge
God, the soul, and reality itself (the true nature of reality) cannot be known through rational means.
10. Faith and Belief
What cannot be known through reason can be the object of faith or reasonable belief. This includes moral freedom, the immortality of the soul, and the existence of God.
11. Truth, Objectivity, and Intersubjectivity
Truth and objectivity, and even intersubjectivity, are possible within the limits of human knowledge.
Perception and the Abstract Concept
Knowledge begins with perception, the knowledge we gain through our senses. It is the knowledge of objects with various sensory qualities (color, shape, etc.). External objects or stimuli affect our sensory organs, producing sensations. These sensations are organized and structured so that we perceive objects with specific qualities (e.g., a white, square, smooth sheet of paper).
Perception involves:
- Sensation
- Laws of perception that organize and structure perceived objects
- Other factors like attention, interest, experience, and concepts
From perception, the human mind forms concepts or ideas, which are universal, abstract, and intangible (e.g., the concept of a book, hand, or table). These concepts are not images of specific objects but general ideas that apply to all instances of that object. Thus, human knowledge can be divided into two levels:
- Perception or sensitive knowledge (acquired through the senses)
- Thought or intellectual knowledge (knowledge through concepts)
Sensations and Sense Perception
Sensation is the direct reception of a specific sensory quality by a sensory organ (e.g., colors by sight, odors by smell). Sensations are particular and are structured within the perceived object. For example, we perceive a colored object or a melody, not isolated colors or sounds.
The process of sensation involves:
- A material stimulus (e.g., light) affects a sensory organ.
- The stimulus is transmitted to the brain as nerve impulses.
- The brain processes the impulses and transforms them into a sensation or sensory quality (e.g., color).
Phases of the Sensation Process
- Physical phase: A stimulus impacts a sense organ (e.g., light hitting the eye).
- Physiological phase: The stimulus is transmitted to the brain as nerve impulses.
- Psychological phase: The brain processes the impulses and transforms them into a sensation (e.g., color).
Thresholds of Sensation
For a sensation to occur, the stimulus must have a certain intensity. If the stimulus is too weak, there is no sensation. If it’s too strong, it can also lead to a lack of perception.
- Threshold: The minimum amount of energy (stimulus) needed to produce a sensation. This is variable.
- Maximum Threshold: The maximum energy beyond which there is no perception.
- Difference Threshold: The minimum change in energy needed to notice a corresponding change in perception.
Classification of the Senses
- Exteroceptors: Senses that receive external stimuli (sight, hearing, smell, taste, touch).
- Interoceptors: Senses that receive stimuli from internal organs and glands, causing sensations like hunger, thirst, and fatigue.
- Proprioceptors: Senses that receive stimuli from muscle, bone, and joint movements, providing information about balance, rest, and movement.