Immanuel Kant’s Philosophy: A Comprehensive Overview
Immanuel Kant’s Philosophy
Objective of Kant’s Philosophy
The freedom of man is guided by reason, both individually and socially. Kant critiques reason to understand its limits and scope. Philosophy should answer these questions:
- What can I know? (Metaphysics)
- What should I do? (Ethics)
- What can I hope for? (Religion)
These are summarized in a fourth question: What is man?
Critique of Pure Reason
Objective: To establish whether metaphysics is possible as a science (knowing God, self, and the world scientifically). It analyzes the characteristics of science and questions if scientific knowledge can be applied to metaphysics. Kant finds that scientific judgments must be:
- Universal
- Necessary
- Progressive (based on trials)
- Synthetic (applicable based on experience)
- A Priori (a product of reason, making them universal and necessary)
Kant examines if these judgments exist in science and if they are possible in metaphysics. He divides his critique of reason into three parts based on the three powers of human knowledge:
1. Transcendental Aesthetic
This section analyzes sensibility (the power with which humans produce knowledge through mathematics). Sensibility applies space and time (which are a priori forms) to sensory data, producing phenomena. Space and time are intuitions belonging to the subject, empty of content. Sensibility orders all sense impressions. Kant synthesizes empiricism and rationalism, acknowledging something a posteriori from experience (sensible data) and something a priori from reason (space and time). The phenomenon we know is not a copy of reality; the subject imposes a priori forms on information from the outside. The subject now governs the laws of the subject. In mathematics (geometry deals with space and arithmetic with time), these are universal and necessary.
Phenomena and Noumena
We only know the phenomenon (what manifests itself sensitively) and not the noumenon (the thing itself, as it exists independently of the subject). The noumenon is unknowable to the subject. The phenomenon is the limit of our knowledge, which is why Kant calls his theory transcendental idealism. In conclusion, scientific knowledge is phenomenal.
2. Transcendental Dialectic
Objective: To study the power of reason to determine the possibility of metaphysics as a science. It concludes that metaphysics is not possible as a science because its statements are not synthetic a priori judgments.
- The self cannot be experienced as a single substance; we only have experience of multiple experiences. Attempting to know the self through reasoning leads to falsehoods.
- We also lack significant experience of the world and cannot scientifically prove its existence.
- We do not have sensitive experience of God and cannot scientifically prove His existence.
Therefore, for Kant, self, world, and God are ideas of reason (realities with meaning but not knowable) that cannot be known scientifically. These ideas are the product of reason’s unifying vocation:
- The idea of self unifies the psychic states of time.
- The idea of world synthesizes all of outer experience.
- The idea of God unifies internal and external phenomena.
For Kant, metaphysics is not a science, but a natural tendency of man.
Critique of Practical Reason
Kant argues that reason has two functions:
- As theoretical reason, it is concerned with being (knowing how things are, science).
- As practical reason, it deals with ought (setting human behavior, morality).
Theoretical reason applies to nature, and practical reason to human existence. Freedom is central to practical reason. Humans exist in two worlds:
- As empirical beings, governed by the laws of nature.
- As rational and self-determining beings, conscious of themselves.
Formalism in Morality
Kantian ethics is a formal ethic, contrasting with material ethics. Material ethics establish a supreme moral good and criticize actions based on their ability to achieve it. Kant rejects material ethics because they are empirical and cannot extract universal principles. They are based on hypothetical imperatives, are heteronomous (laws imposed from outside), and the will is determined to action by an end outside the subject. Formal ethics should be:
- A priori (to have universal principles)
- Based on categorical imperatives
- Autonomous (the subject gives the law to itself)
Kantian formal ethics has no content (it doesn’t tell us what to do, but how to act). It distinguishes three types of action:
- Breach of duty
- Conformity with duty
- Action from duty
A person acts morally when acting from duty, not for utility or satisfaction.
Categorical Imperative
Kant discovers that reason imposes a categorical imperative on the subject to behave as follows:
- Act so that your maxim could be taken as a universal law.
- Always treat humanity as an end, never as a means.
- Consider yourself the author of universal moral laws.
Kantian ethics is autonomous, and it is the subject’s reason that gives itself the moral law.
Postulates of Practical Reason
While the Critique of Pure Reason denied the possibility of metaphysics as a science, Kant maintains that practical reason and moral principles can achieve the objectives of metaphysics. For Kant, freedom, God, and the immortality of the soul are imposed on the mind as postulates of practical reason:
- Freedom: We must act as if we are free to fulfill our duty.
- Immortality of the soul: Reason commands us to aspire to virtue, but it is unattainable in a limited existence. Therefore, the soul must be immortal.
- God: The discrepancy between what is and what ought to be requires the existence of a supreme being in which virtue and happiness are united.