H. P. Grice, "Conversational rigourism"

rigorism, the view that morality consists in that single set of simple or unqualified moral rules, discoverable by reason, which applies to all human beings at all times. It is often said that Kant’s doctrine of the categorical imperative is rigoristic. Two main objections to rigorism are 1 some moral rules do not apply universally  e.g., ‘Promises should be kept’ applies only where there is an institution of promising; and 2 some rules that could be universally kept are absurd  e.g., that everyone should stand on one leg while the sun rises. Recent interpreters of Kant defend him against these objections by arguing, e.g., that the “rules” he had in mind are general guidelines for living well, which are in fact universal and practically relevant, or that he was not a rigorist at all, seeing moral worth as issuing primarily from the agent’s character rather than adherence to rules.