Phillipa Foot 1972
Foot argues against the Kantian distinction of hypothetical & categorical imperatives.
Kant defines an hypothetical imperative as one that says only that an action is good to some purpose. Categorical imperative on the other hand, presents an action that is itself objectively necessary, without regard to any other end.
This means-end independence (reason giving nature) of the CI is problematic when looking at claims of should and ought. We ought act according to a CI, because that's what morality requires, where are we ought act according to an HI, only if we desire some end.
Foot's claim is that the ought of a CI is always hypothetical to some end. She rejects the means-end independence of the necessity of the CI's ought because it fails to distinguish between CI & non-CI oughts like morality and etiquette.
Furthermore, hypothetical imperatives are not all the result of selfishness, egoist or ulterior motives. Actions like charity could be required under an HI whenever the virtue of charity or the welfare of others is valued.
bibtex
@article{foot1972morality, title={Morality as a system of hypothetical imperatives}, author={Foot, P.}, journal={The Philosophical Review}, volume={81}, number={3}, pages={305--316}, year={1972}, publisher={JSTOR} }