Rules can collide with catastrophe
Strict duties, especially truthfulness, can appear to require material cooperation with terrible consequences.
Modern philosophy · 1724–1804
Immanuel Kant
Kant asks what rational agents must demand of themselves, treating persons as law-makers who may never be reduced to convenient instruments.
Immanuel Kant was a Prussian philosopher who spent his working life in Königsberg. His critical philosophy transformed debates about the limits of knowledge, the authority of moral duty, political right and aesthetic judgement.
EthicsKnowledgeJustice
The question he enters
The question Immanuel Kant enters
Could you will the principle behind your action as a rule for everyone—and does it respect each person as an end?
The central move
Test the maxim, not the excuse
Kant shifts moral attention from the outcome a person hopes for to the principle on which they act. A good will acts from duty under a law rational agents can share. The humanity formulation adds a second pressure: never treat rational nature merely as a means, even when doing so would produce an attractive result.
Key ideas
Terms that carry the argument.
- Good will
- A will committed to acting for the sake of duty, not merely in conformity with it.
- Maxim
- The subjective principle or policy on which a person proposes to act.
- Categorical imperative
- An unconditional moral requirement binding rational agents regardless of their contingent aims.
- Humanity as an end
- The requirement to respect rational agency and never use a person merely as an instrument.
Where the view strains
Objections and limits.
The maxim can be written strategically
A person may describe an action narrowly enough to make universalisation look easier than it is.
Sources and routes
Read the work. Follow the argument.
Primary texts
Where to meet the position.
- Project GutenbergGroundwork of the Metaphysics of MoralsWebGood will, duty and the principal formulations of the categorical imperative.Thomas Kingsmill Abbott translation; Project Gutenberg title: Fundamental Principles of the Metaphysic of Morals. · Readable online with downloadable ebook formats from the catalogue page. Checked Aug 2026.
- Project GutenbergCritique of Pure ReasonWebThe conditions and limits of possible experience and knowledge.J. M. D. Meiklejohn translation · Free English full text and downloads. Checked Aug 2026.
- Online Library of LibertyThe Metaphysics of MoralsWeb · PDF · EPUBA developed account of right, virtue and duties.William Hastie's 1887 translation of the Doctrine of Right · Free HTML, PDF and EPUB editions. Checked Aug 2026.
- Project GutenbergThe Metaphysics of MoralsWebA developed account of right, virtue and duties.Thomas Kingsmill Abbott translation of the Doctrine of Virtue · Free English full text and downloads. Checked Aug 2026.
On this site
Continue in a usable resource.
EthicsRelevantUnit · Duty, universalisability, motive and respect for persons.When is punishment justified?RelevantInquiry · Retribution, proportionality and the refusal to punish merely for social advantage.Would This Annoy Kant?Appears hereGame · Test maxims, motives and respect for persons across awkward cases.Kant at the DoorAppears hereGame · Put strict truthfulness under escalating pressure.Who Said It?Appears hereGame · Identify Kantian claims about duty without confusing them with empty rule worship.