One of the dominant theories in the study of ethics is Plato's conception of the universal good, the doctrine of forms. He said that there exists an absolute good which is the source of all goodness of whatever form or kind in the universe. It is difficult to criticize the views of a beloved former teacher, but one must give his highest allegiance to truth.
First, contrary to Plato's theory, there must be many kinds of good, not a single universal ideal, since the good seems to be relative to particular individuals, places, circumstances, and times. A single ideal cannot encompass both the absolute and the relative. Good has no single meaning common to all its applications.
Second, the idea of good is used in many different categories. There cannot be an ideal of the good at one time common to the concept of the good as such, the good as the essence of something, and the good as a relation between things. The things categorized under a single platonic form are things of a single science, discipline, or kind, yet there are different standards of the good in different fields, and even at times in the same field. There is no form of the good separate from its particular, finite manifestations.
This platonic concept of the good as an absolute value has no practical application and is of little value in everyday affairs (e.g., knowledge of the ideal is of little or no use to a carpenter or doctor, each seeking to attain the good appropriate to his particular function). In our study we must arrive at a formulation of the good that is within the reach of human perception. We recognize that the practical good varies in its applications.