Mackie nonetheless explores the generalities and rehearses ideas and arguments that stem from from many sources. I am a reasonably benevolent person, I want happiness and contentment. Fly me to the moon and let me sit amongst the stars. It is a synergy - more than a sum of individual enjoyments. The 3 Cs are key to the argument.
Cooperative action extends the scope of self-referential altruism.
A stable, working economic system requires cooperation independent of personal affection or goodwill. We develop political and technical organisations to ensure that the conditions for this exist. But self-love and confined generosity means also accepting competition and conflict as natural conditions between individuals and groups. On this basis Mackie argues that moral absolutism is impracticable and implausible. Like Lisa's bucket - they leak.