In no time and in no country have moralists agreed on the definition of good and evil. Some have identified good with the useful, the true, the advantageous or the pleasant Others have seen it as that which conforms with nature or with the will of God. As to evil, it has been equated with suffering, injustice and ignorance or put down to the prompting of Satan.
Thus the notions of good and evil have always remained various and uncertain. Pleasure is the only good and pain the only evil, said Aristippus of Cyrene. True good has nothing to do with pleasure, answered the Stoics; it resides in knowledge of the order of things and springs from reason. In order to survive, we must ourselves conform to nature and the whole of nature is steeped in God. In Epictetus and Marcus Aurelius the notion of good was confused with that of brotherly love, resignation and submission to the divine will. For the Jews, and later for the Christians, it had a far more definite meaning. The commandments given by God
Himself were laid down in the sacred books of the Old and New Testaments. Thus the moralist, like a lawyer interpreting the legal code, could determine without difficulty what was good and what was evil. In principle it was this idea of the lawful and the forbidden which governed the conduct of men in the West up to the end of the Middle Ages. Nevertheless, the morality of pleasure continued its career unperturbed through the centuries. Rejuvenated by Helvetius and Jeremy Bentham, it became the morality of self-interest. Its success then became overwhelming for man is always ready to take egoism as his supreme guiding principle. In modern democracies, the good became definitely identified with the useful. Egoism proved itself stronger than love. Epicurus vanquished Christ.
Only a very small minority still accepts the definition of good and evil traditional in Western civilization. The majority have forgotten the Ten Commandments; many even ignore their very existence. There is no longer any universally recognized frontier between licit and illicit. Most people do not distinguish clearly between good and evil. They are not even capable of taking enlightened selfishness as the arbiter of their actions. They are content to obey their appetites and to pursue their immediate advantage. Good is merely profit. Since courage exposes one to useless dangers, it is better to be a coward than a corpse. A motorcar is preferable to a child. The great thing is to earn as much as possible while working the bare minimum. Nevertheless, honesty, loyalty, disinterestedness and heroism are still preached.
Thus there is immense confusion in the mind of modern man. Obviously, the members of human communities should learn to behave according to identical principles. They ought to accept a single definition of good and evil as they accept a single definition of heat and cold.
Such a definition is possible today in the light of the fundamental laws of human life. The lawful can be distinguished from the forbidden with complete certainty. The knowledge of these laws enables us to define good and evil clearly and unalterably and in a way that is intelligible to every individual endowed with reason. Good consists in what conforms to the essential tendencies of our nature. It comprises those things, thoughts, feelings and acts which tend to conserve life, to propagate the race, to heighten the mental perception of the individual and to raise the spiritual level of mankind. Evil, on the contrary, is that which is opposed to life, to its multiplication or to its spiritual development The supreme good, in fact, is indistinguishable from the success of life in its specifically human aspect.
When it comes to the triumph of the spirit, good and evil assume a certain complexity. They include not only factors which help or hinder life, considered as a whole or in one of its aspects, but also those which produce harmony or disharmony in our physical and mental activities.
There are things which are evidently bad because they kill, paralyze, corrupt or diminish the individual. Such things, for example, are the plague bacillus, the yellow fever virus, alcoholic excesses, tuberculosis, the movies and the radio. Equally bad are the exclusive development of the intellect at the expense of physical robustness, of the tolerance of dirt, discourtesy and the habit of denigration. Other evils are lack of self-mastery, incapacity for effort and the spirit of deceit. On the contrary, air, water, light, science, art and religion represent essential aspects of good as do the capacities for love, zeal and action. For all these factors make for the heightening of personal and social life.