Explanation
Why Kant starts with ordinary morality
Kant believes common moral understanding already distinguishes duty from advantage. Philosophy does not invent morality; it identifies the rational structure implicit in ordinary judgements and protects it from convenient exceptions.
Good will and results
Calling good will unconditionally good does not mean consequences are irrelevant to competent action. It means moral worth cannot be cancelled by bad luck or guaranteed by accidental success. The agent remains responsible for choosing means intelligently within available knowledge.
Acting from duty
Kant isolates the motive of respect for law to explain distinctively moral worth. This need not imply that affection makes an action worthless. The difficult case is whether the law would still determine the choice when inclination did not support it.
Maxims
A maxim is the agent’s practical principle: what the person proposes to do, in what circumstances and for what end. Universalisation tests that principle, so vague or strategically narrow descriptions can distort the result. Formulating a maxim honestly is part of moral judgement.
Hypothetical and categorical imperatives
A hypothetical imperative depends upon an adopted end: anyone who wants the result has reason to take necessary means. A categorical imperative applies regardless of optional aims because it concerns the conditions of rational willing itself.
Contradiction in conception
Some maxims defeat the institution or practice they presuppose when universalised. Universal false promising would destroy the trust that makes a promise function, so the maxim cannot coherently become universal law.
Contradiction in will
Other maxims describe a conceivable world but cannot be rationally willed by an agent who necessarily adopts ends. A universal refusal of assistance can conflict with the support any finite rational being may require.
Perfect and imperfect duties
Perfect duties prohibit particular maxims and normally allow no discretionary exception. Imperfect duties require ends such as self-development and the happiness of others, while leaving latitude about time, method and degree.
Humanity as an end
Humanity refers to rational agency—the capacity to form purposes and act on principles. Treating a person merely as a means bypasses or manipulates this capacity. Informed cooperation uses one another’s services without reducing either person to an instrument.
Dignity and price
Something with a price can be exchanged for an equivalent. Dignity marks value that must not be traded away in this manner. Kant locates it in autonomy and the capacity to participate in moral legislation.
Autonomy
Autonomy is not doing whatever one happens to want. It is rational self-legislation under principles one can justify universally. A person ruled by appetite, manipulation or external reward is heteronomous even when describing the choice as personal freedom.
The kingdom of ends
This ideal asks agents to view themselves as legislators and subjects in one moral community. It makes reciprocity explicit: principles must be fit for a system in which every rational person has equal standing.
Why happiness cannot ground morality
Kant does not deny that happiness matters. He denies that its pursuit produces necessary and universal obligation, because people disagree about its content and because commands based upon desire remain conditional.
Freedom and two standpoints
The sensible and intelligible standpoints are not two separate human beings. They are two ways of considering the same agent: as an event within nature and as a reason-responsive source of action. Kant uses this distinction to make responsibility compatible with natural causation without claiming theoretical proof of freedom.
A disputed circle
Kant appears to infer morality from freedom and freedom from the moral perspective. He responds by distinguishing the practical presupposition of freedom from theoretical knowledge, but interpreters continue to debate whether the argument genuinely avoids circularity.
The limits of explanation
If freedom were explained completely through natural causes, it would no longer be the independence required by autonomy. Kant therefore treats the final limit not simply as missing information but as a boundary imposed by the kind of concept under investigation.
Consequences and moral conflict
Critics argue that strict duties can ignore disastrous outcomes or genuine clashes of obligation. Kant’s framework instead emphasises principles that respect every agent. Later Kantian ethics often develops more detailed accounts of judgement, institutions and competing claims.
Continuing importance
The language of persons as ends, equal moral standing and dignity has influenced ethics, political philosophy and human-rights discourse. Even opponents of Kant commonly frame their objections through the problems he made unavoidable.