Full Idea
Kant fails, almost grotesquely, to show that there would be any logical or physical impossibility in the adoption by all rational beings of the most outrageously immoral rules of conduct.
Gist of Idea
Why couldn't all rational beings accept outrageously immoral rules of conduct?
Source
comment on Immanuel Kant (Groundwork of the Metaphysic of Morals [1785]) by John Stuart Mill - Utilitarianism Ch.1
Book Reference
Mill,John Stuart: 'Utilitarianism (including On Liberty etc)', ed/tr. Warnock,Mary [Fontana 1962], p.254