John Stuart Mill: '"though the consequences in the particular case might be beneficial—it would be unworthy of an intelligent agent not to be consciously aware that the action is of a class which, if practiced generally, would be generally injurious, and that this is the ground of the obligation to abstain from it."'
rld (even if living in the real world means less happiness). A related example would be carrying out the wishes of the dead. It can't increase the happiness of a deceased person to carry out their will (because they're dead). However, if a deceased person expressed a preference for their money to be donated to the local cat shelter, say, then it seems there is a moral obligation to honour this preference. Act utilitarianism, though, would say we should ignore the preferences of the deceased and just spend the money in whichever way maximises happiness – but this seems wrong. Preference utilitarianism can avoid this outcome and say we should respect the preferences of the dead.
Preference utilitarianism can also tie in with Mill's distinction between higher and lower pleasures. Mill claims that higher pleasures are just inherently more valuable than lower pleasures, but preference utilitarianism can explain this in terms of preference: We prefer higher pleasures over lower pleasures, and so should seek to maximise those.
The only thing that is good without qualification is good will. Good will means acting for the sake of duty. You have a duty to follow the moral law. Moral laws are universal. You can tell is a maxim is universal if it passes the categorical imperative. The categorical imperative is two tests: Contradiction in conception and Contradiction in will. Finally, do not treat people as means to an end (the humanity formula).
Deontology (as in Kant's deontological ethics) is the study of duty. Kant argues that we each have a duty to follow the moral law. The moral law, according to Kant, is summarised by the categorical imperative.
"Act only according to that maxim whereby you can at the same time will that it should become a universal law without contradiction." - Kant, Grounding for the Metaphysics of Morals
Assuming the maxim does not result in a contradiction in conception, we must then ask whether the maxim results in a contradiction in will – i.e. whether we can rationally will a maxim or not.
"Act in such a way that you always treat humanity […] never simply as a means, but always at the same time as an end." - Kant, Grounding for the Metaphysics of Morals
Philippa Foot argues that moral laws are not categorical in the way Kant thinks – there is no categorical reason to follow them. Instead, she argues, morality is a system of hypothetical imperatives.