's The Republic argued that, "In the world of knowledge the idea of good appears last of all, and is seen...to be the universal author of all things beautiful and right". Silent contemplation was the route to appreciation of the Idea of the Good. Aristotle in his Nicomachean Ethics accepted that the target of human activity, "Must be the 'Good', that is, the supreme good.", but challenged Plato's Idea of the Good with the pragmatic question: "Will one who has had a vision of the Idea itself become thereby a better doctor or general?". However, arguably at least, Aristotle's concept of the unmoved mover owed much to Plato's Idea of the Good.
Hellenic syncretism
of Alexandria conflated the Old TestamentGod with the unmoved mover and the Idea of the Good. Plotinus, the neoplatonic philosopher, built on Plato's Good for his concept of the supreme One, while Plutarch drew on Zoroastrianism to develop his eternal principle of good. Augustine of Hippo in his early writings offered the summum bonum as the highest human goal, but was later to identify it as a feature of the Christian God in De natura boni. Augustine denies the positive existence of absolute evil, describing a world with God as the supreme good at the center, and defining different grades of evil as different stages of remoteness from that center.
Later developments
The summum bonum has continued to be a focus of attention in Western philosophy, secular and religious. Hegel replaced Plato's dialectical ascent to the Good by his own dialectical ascent to the Real. G. E. Moore placed the highest good in personal relations and the contemplation of beauty – even if not all his followers in the Bloomsbury Group may have appreciated what Clive Bell called his "all-important distinction between 'Good on the whole' and 'Good as a whole'". The doctrine of the highest good maintained by Immanuel Kant can be seen as the state in which an agent experiences happiness in proportion to their virtue. It is the supreme end of the will, meaning that beyond the attainment of a good will, which is moral excellence signified by abiding by the categorical imperative and pure practical reason, the attainment of happiness in proportion to your moral excellence is the supreme, unconditional motivation of the will. Furthermore, in virtue of the doctrine of the highest good, Kant postulates the existence of God and the eternal existence of rational agents, in order to reconcile three premises: that agents are morally obligated to fully attain the highest good; that the object of an agent’s obligation must be possible; that an agent’s full realization of the highest good is not possible.
Judgments
Judgments on the highest good have generally fallen into four categories:
Utilitarianism, when the highest good is identified with the maximum possible psychological happiness for the maximum number of people;