An Imperative ought (imperative moral principle) is put forward as somehow universally binding regardless of people’s needs and preferences. Kant’s categorical imperatives (for example “Only act in ways that you would consent to becoming universal rules”) are prime examples of moral principles that are claimed to be imperative.
No means has ever become generally accepted by which physical reality makes such oughts binding. No source of rational justification for accepting the burdens of a moral principle regardless of people’s needs and preferences has ever become generally accepted. Till some means by which reality makes such oughts universally binding or some source of rational justification for them being binding has become generally accepted, I will feel free to refer to all claimed Imperative oughts as ‘magic’ oughts.
Enforced cultural norms (moral standards) may be commonly presented as imperative and universally binding. But it is empirically true that when following them would be against the needs and preferences of the group as a whole, such norms suddenly become less binding. Mindlessly following them can even be viewed as deserving punishment (being immoral). For example, mindlessly following “Do unto others as you would have them do unto you” when dealing with criminals and in times of war.
If it Altruistic Cooperation morality is not an imperative, what use is it?
It is of the same use as the rest of science. It informs instrumental oughts based on facts and desires. For example, “Based on science from game theory and human psychology, you ought (instrumental ought) to, almost always, accept the burdens of Altruistic Cooperation morality if you desire to increase your durable well-being over your lifetime”.
In the future, perhaps some other instrumental ought regarding some other moral principle, perhaps meeting some different overriding desire, will be more attractive for adoption and practice. Or perhaps some clever philosopher will convince everyone of the reality of some imperative ought. Until either of these events occur, the proposed Altruistic Cooperation moral principle is arguably the best instrumental choice for groups to base enforced norms on and individuals to practice in order to achieve common overriding desires that can be best met by altruistically cooperating in groups.