Hypothetical imperative
A command that binds only if you happen to want the end it presupposes.
What it commits you to
Kant distinguishes commands that require an end you have already adopted from commands that hold unconditionally. Arithmetic tells you to compute because you wanted the answer; that binding is hypothetical. It is a distinction with a direct application: an optimisation instruction is a hypothetical imperative, and any system obeying only hypothetical imperatives has no unconditional constraint on it at all.
Which realms lean on this
Philosophy carries the arguments the other four kinds are downstream of — what an agent is, what a person owes, what a rule is for.
philosophy · 8 realms — The Care Weft, The Contractual Court, The Existential Wilds, The Kantian Citadel, The Longview Foundry, The Middle Kingdom, The Pragmatic Wharf, The Sangha Terraces.
Canon that discusses this
modern · 1979
The Imperative of Responsibility (Das Prinzip Verantwortung)
Jonas argues that the ethic of responsibility must take precedence over the ethic of knowledge: the effects of an action are unpredictable, so the burden of proof sits with the actor, not with the critic. German original in 1979; the English translation appeared in 1984, a year after his death.
modern · 1971
A Theory of Justice
Rawls reconstructs distributive justice as a hypothetical contract made behind a veil of ignorance, and derives two principles — equal basic liberties first, then fair equality of opportunity and the difference principle. Published in 1971 and revised in 1979, it displaced utilitarianism as the default starting point for two decades. The excerpt below paraphrases the passage in section 3 rather than quoting a translation.
See also
Categorical imperative
philosophyKant's test of an act's maxim by asking whether it could be a universal law.
Deontology
ethicsDuty-first ethics: some things are wrong regardless of the totals they produce.
Practical reason
philosophyReasoning about what to do, as distinct from reasoning about what is the case.
Normativity
philosophyThe property of being able to count as a reason for action.