Philosophy: Wikipedia entry on the categorical imperative, Eskimo killing children:
The categorical imperative is the central philosophical concept of the moral philosophy of Immanuel Kant, and of modern deontological ethics. Kant introduced this concept in Groundwork of the Metaphysics of Morals. Here, the categorical imperative is outlined according to the arguments found in his work.
Kant thought that human beings occupy a special place in creation and that morality can be summed up in one, ultimate commandment of reason, or imperative, from which all duties and obligations derive. He defined an imperative as any proposition that declares a certain action (or inaction) to be necessary. A hypothetical imperative would compel action in a given circumstance: If I wish to satisfy my thirst, then I must drink something. A categorical imperative would denote an absolute, unconditional requirement that exerts its authority in all circumstances, both required and justified as an end in itself. It is best known in its first formulation:
Kant's Categorical Imperative: "Act only according to that maxim whereby you can at the same time will that it should become a universal law."
Statement: Morality is Universal; Cultural relativism is false.
Objection 1: Eskimos killing children for the survival of the tribe is considered moral; killing children in USA is considered immoral; therefore cultural relativism is true.
What's considered moral is different in different societies; therefore cultural relativism is true.
Eskimos killing children for the survival of the tribe is Universally immoral because of the categorical imperative.
Objection 1: Thought experiment: Two poisoned people with one antidote. What would be the moral thing to do?
Assumption: Not taking the pill would be killing oneself; killing oneself is immoral; therefore there is no moral act in that situation.
Objection 2: If it is moral to put one person in prison, then it is moral to put everyone in prison (regardless of their provocation)
Assumption: Provocations are irrelevant to a maxim
Question: Are answers to all moral questions about actions either that they are moral or immoral, or is there a middle ground? (If an act is not immoral, can it be also be not moral?)
Telling the truth to the murderer is required because moral actions do not derive their worth from the expected consequences.