Who was Kant and what did he ask?
Immanuel Kant lived in Königsberg (Prussia) from 1724 to 1804 and is a central thinker of the Enlightenment. His motto for the Enlightenment was "Dare to use your own reason". He wrote three Critiques. A critique here means a careful check of what a power of the mind can and cannot do.
- Critique of Pure Reason (1781): What can I know?
- Critique of Practical Reason (1788): What ought I to do?
- Critique of Judgement (1790): beauty and purpose.
He also wrote the short Groundwork of the Metaphysics of Morals (1785), the book most students read for his ethics.
The Copernican turn and the theory of knowledge
Before Kant there were two camps. Rationalists (Descartes, Leibniz) said reason alone gives true knowledge. Empiricists (Locke, Hume) said all knowledge comes from the senses. Hume even doubted that we see cause and effect at all.
Kant's answer: "Thoughts without content are empty; intuitions without concepts are blind." We need sense data and the mind's concepts together.
Copernicus moved the Sun to the centre. Kant made a similar turn: instead of the mind fitting itself to objects, objects must fit the mind. Our mind has fixed forms of intuition (space and time) and categories (like cause and effect, unity, substance). That is why every experience is in space and time and follows cause and effect.
Kinds of judgements
- Analytic: true by meaning alone ("All triangles have three sides").
- Synthetic: adds new information ("This room is cold").
- A priori: known before experience; a posteriori: known from experience.
Kant's surprise: maths and the base of physics give synthetic a priori judgements, such as 7 + 5 = 12 or "every event has a cause". They are new and yet certain, because they come from the mind's own forms.
Limits of reason: phenomena, noumena and metaphysics
Phenomena are things as they appear to us through space, time and the categories. Noumena (things in themselves) are things as they are apart from our mind. We can think noumena but never know them.
Old metaphysics tried to prove the soul is immortal, the world has a start, and God exists. Kant showed reason then goes beyond experience and falls into antinomies: two opposite claims that both seem provable (e.g. "the world had a beginning" and "the world had no beginning").
So metaphysics cannot be knowledge like science. But God, freedom and the immortal soul remain postulates of practical reason: we must assume them to make sense of moral life. Kant said he had to limit knowledge to make room for faith.
Deontological ethics: good will and duty
Deontology (from Greek deon, duty) judges actions by duty and rules, not by results. For Kant, the only thing good without limit is a good will.
- Acting against duty: cheating a customer.
- Acting in line with duty but for self-interest: honest only to keep customers.
- Acting from duty: honest because it is right. Only this has moral worth.
Kant separates hypothetical imperatives ("If you want marks, study") from the categorical imperative, which binds everyone, always, with no "if". Morality must come from our own reason: this is autonomy. Following outside pressure or desire is heteronomy.
The categorical imperative: two main formulas
In chapter 2 of the Groundwork Kant gives several formulas. Two are key:
- Universal law: Act only on that maxim (personal rule) which you can at the same time will to become a universal law.
- Humanity: Treat humanity, in yourself and in others, always as an end and never merely as a means.
Worked test, the lying promise: Maxim: "When I need money, I will promise to repay though I know I won't." Universalise it: if everyone did this, nobody would believe promises, so the trick could not work. The maxim destroys itself. It also uses the lender merely as a tool. So it is forbidden.
A third formula, the kingdom of ends, asks us to act as a law-making member of a community where everyone is treated as an end.
Criticism
Critics say duties can clash (truth vs saving a life), the rules are too strict, and results matter. Utilitarians judge by consequences instead.
Key formulas and definitions
- Knowledge = sense data + concepts of the mind
- Forms of intuition: space, time; categories: cause, unity, substance…
- Phenomena = things as they appear (knowable); noumena = things in themselves (unknowable)
- Synthetic a priori: new and certain (7 + 5 = 12; every event has a cause)
- Categorical imperative 1: act only on a maxim you could will as universal law
- Categorical imperative 2: treat humanity always as an end, never merely as a means
- Hypothetical imperative = "if you want X, do Y"; categorical = "do Y" with no if
Worked examples
1. Test the maxim: "I will cut the queue whenever I am in a hurry."
Universalise: if everyone cut queues when in a hurry (and everyone is often in a hurry), there would be no queue to cut. The maxim cannot work as a universal law, so it fails test 1. It also treats the people waiting merely as obstacles, so it fails test 2.
2. Classify: (a) "All bachelors are unmarried" (b) "It is raining in Mumbai" (c) "Every change has a cause".
(a) Analytic a priori: true by meaning. (b) Synthetic a posteriori: new information from experience. (c) Synthetic a priori: adds information but is known with certainty, because cause is a category of the mind.
3. A doctor helps a poor patient only because a camera is filming her. Does the act have moral worth for Kant?
The act is in line with duty (helping) but not done from duty; the motive is reputation. So for Kant it has no moral worth, though it is not wrong. If she would help even with no camera, because it is right, it would have moral worth.
Common mistakes
- Thinking Kant judged actions by their results; he judged them by the maxim and the motive (duty).
- Saying "never use people as a means". Kant says never merely as a means; using a shopkeeper to buy bread while respecting him is fine.
- Thinking noumena do not exist; Kant says we can think them but cannot know them.
- Mixing up hypothetical ("if you want…") and categorical (no condition) imperatives.