There is nothing either good or bad but thinking makes it so.
This is one of Shakespeare’s most popular quotes, especially among philosophers. And no wonder: it is moral relativism in a nutshell.
“Goodness,” as a concept, is famously difficult to analyze. Plato conceived of the Good as something external to the human mind, more real than the material world. Aristotle, always more prosaic, said that the ultimate good was happiness, since we desire other things for the sake of happiness but never desire happiness for the sake of other things. Recently I read Epicurus, more naturalistic even than Aristotle, who thought goodness was pleasure, pure and simple.
The concept of goodness obviously plays an important role in religions as well as philosophy. Zoroastrians conceived of life as a cosmic battle between the forces of good and evil. In Judaism, goodness is similarly seen as something objective. Hamlet is prophetically damned in the Book of Isaiah (5.20): “Woe unto them that call evil good, and good evil; that put darkness for light, and light for darkness; that put bitter for sweet, and sweet for bitter!” In Christianity, good is often conceived of as God’s will (leading to Plato’s famous Euthyphro dilemma: does God will things because they’re good, or are they good because God willed them?)
The Christian concept of an objective, ideal good—influenced by Plato—held sway in Europe for a long while. Morality was conceived of as absolute and objective. What is good for me is good for you; what was good in ancient days is still good today.
In Shakespeare’s day, however, the idea of moral relativism began to take hold in the European mind. About sixty years after Hamlet’s aphorism, Spinoza had this to say:
As for the terms good and bad, they indicate no positive quality in things regarded in themselves, but are merely modes of thinking, or notions which we form from the comparison of things one with another, thus one and the same thing can be at the same time good, bad, and indifferent. For instance, music is good for him that is melancholy, bad for him that mourns; for him that is deaf, it is neither good nor bad.
If you physically or chemically analyze an object, you will never find goodness or badness in it. Those are judgments, and thus exist in our perception of objects, not in the objects themselves. We have learned this lesson very well in the modern world, which is why we frequently dismiss things as “subjective.”
There does seem to be a limit to moral relativism, however, and a danger in pushing it too far. I discussed this in regards to Milton’s quote about making a hell of heaven and a heaven of hell. Some situations are quite simply unfair, dehumanizing, exploitative, or painful. Those judgments, too, only exist in the mind; but every mind is attached to a body, and every body has certain limits and needs. The mind, too, is not infinitely flexible; some things we simply cannot accommodate. This is why long-term solitary confinement, for example, is unambiguously bad: it deprives the mind of something it needs.
For this reason, I cannot fully agree with Hamlet. Because of the constitution of our brains and bodies, some things are almost always bad, and others good. Nevertheless, for most of us in daily life, I suspect that our judgments of reality cause us more pain than the reality itself. Of course this is not always so; the world has many genuine problems.
The wise course, it seems to me, is to strike a balance between striving to improve the world around us, and striving to make peace with what we cannot change.