Immoral actions are those you cannot will everyone to do.

The maxim of an immoral action is self-undermining.

The maxim of an action that does not consider the desires of others is incoherent.

Hypothetical imperatives are formulated after considering various plausible hypotheses; categorical imperatives are rules of thumb that can be applied instantly.

Categorical imperatives are commands that only have to be followed if the chances of success are high enough, whereas hypothetical imperatives always apply.

Categorical imperatives are applied and practical, whereas hypothetical imperatives are purely theoretical.

Hypothetical imperatives depend on the agent's aims; categorical imperatives apply independently of the agent's aims.

The application of categorical imperatives is limited to one category of actions, whereas hypothetical imperatives apply universally.

Act in such a way as you could want others to act.

Treat all other human beings equally.

Treat other human beings as ends in themselves.

Imagine yourself in the place of the other person when deciding how to treat others.

Act according to a law that you impose on yourself.

Respect for the moral law

Social convention

Self-interest

Inclination

Legal pressure

Section I clarifies why it must be immoral to act from egoistic motives.

Section I presupposes that there is a universal law of morality and asks:  What would its content be?

Section I defends Hume's distinction between relations of ideas and matters of fact.

Section I clarifies common moral concepts, focusing on 'good will', 'duty', 'respect' and 'law'.

Section I attempts to determine whether there is a moral law.

The Neo-Humean definition of rationality is too broad.

Doing what achieves aim A is rational only if A is a rational aim.

Whether it is rational or not to do X partly depends on cultural norms.

Desires cannot cause actions; they can only justify them.

...the debate between non-cognitivsts and cognitivists has been going on for half a century.

...practical rationality tells us that moral claims are often subjective.

...practical rationality is the same as instrumental rationality.

...practical rationality must encompass more than only instrumental rationality.

...neo-Humeanis/subjectivism is, all things considered, the most plausible position in metaethics.

... Quinn misunderstands their position.

... Hume's distinction between matters of fact and relations of ideas prevents the difficulty Quinn imagines.

... Quinn's imaginary scenario does not resemble anything we would recognize as a desire and does hence not constitute a counterexample.

... Quinn's objection was already conclusively refuted by Hume in his Treatise.

... Quinn's own conception cannot work because reason must be "the slave of the passions."