Axiology [Greek, axios, value, worth, and logos, reason, account] is the philosophical science of values. It investigates the nature, criteria, and ontological status of values. It is a modern term but it had its origin in Plato's theory of Forms or Ideas (the Idea of the Good), and was developed by Aristotle in his Organon, Ethics, Poetics, and Metaphysics (Book Lambda). The Stoics and Epicureans investigated the summum bonum [the highest good]. The Neo-Platonist identified the good with being; ens est umun, veritas, bonum, [being is one, true and good]. Thomas Aquinas built on Aristotle's identification of the highest value with the final cause in God as "a living being, eternal, most good."
The fact that there is no universal and necessary criterion of values, of right and wrong, is explained by the human freedom of choice. Each person has the freedom to choose his own criterion of values. But not all men choose the same criterion of values. This accounts for the fact that there is no universal and necessary criterion of values. But from the fact that there is no universal and necessary criterion of values, it does not follow that man does not choose any criterion of values. Though each person may choose his own criterion of values, he cannot avoid making the choice. Man has the freedom of choice, whether he believes it or not. And every attempt to eliminate value judgments presupposes and involves the value judgment that is good and right to eliminate value judgments.
Since value judgments cannot be eliminated from human discourse, the problem of values can not be avoided. The fact that there is no universally accepted absolute standard of values does not mean that there is no absolute standard of values. The rationalistic theory of value (that there is a universal and necessary criterion of values) is not the only theory of an absolute theory of values. Thus our problem: "What is the criterion of values? What shall I choose as the criterion of the good?" becomes upon analysis "What is the true absolute criterion of values? What absolute criterion shall I choose as the criterion of the good?"