Morality is the differentiation of actions proper and improper; generally defined 'morals' is that language that contains imperatives: what humans should do (as sentences, called 'norms').

When we wonder why there seems to be a lack of behavior that follows these morals in the world, we approach the concept of morality from a descriptive sense (we observe that human behavior has changed). Increased insight in this pursuit is found when we examine how humans themselves have approached morality from a normative sense (what is actually proper and improper). When humans have considered morality they have come to understand that the morals humans proclaim—again, language that contains imperatives—either correspond to real, objective moral facts ("Moral Realism") or are merely invented delusions expressing human emotions ("Moral Nonrealism").

Prior to the Enlightenment, there was a category of accepted knowledge outside of empirically observed nature (e.g., the non-natural, supramundane, supernatural, etc). The Enlightenment itself was a shift in human thinking that rejected this category as invalid, switching our criteria of acceptable knowledge to the material, to the empirically observed.

The shift in thinking did not happen all at once. Certain beliefs remained, held over from earlier times—somewhat as dependencies—until they could be examined and dismantled individually if they lacked empiric evidence. Western society's assumption that objective Moral Facts existed in a material universe remained for some time until examined by David Hume in 1738 in his A Treatise of Human Nature. Here Hume observed the difficult reality of the relationship between facts (that which is) and values (that which we claim ought to be), concluding that we cannot assert prescriptive or normative values based on descriptive facts.

Hume's Is-Ought observation upset the world, and has resulted in our modern condition. If empirical observation is categorically never able to locate oughts, a world that accepts Empiricism alone is one forced from Moral Realism to Moral Nonrealism: morals no longer correspond to Objective Facts, but can only be understood as invented whims and emotions, which—apart from society's ability to enforce or inflict punishment for as a conditional consequence (what Kant termed 'hypothetical morality')—can be ignored without consequence.

The transition from a society whose intellectuals and leaders held Moral Realism (viz, Christendom) to one where artists, philosophers, and intelligentsia hold Moral Nonrealism (the Modern West) has been a long, painful process since 1738. The Marquis de Sade astutely summed up the painful condition of man following Hume's revolution in thought saying "If there is no God, then everything that Is, is Right" and the majority of Western thought since then has either been in reaction against this belief (i.e., revivals of Evangelical Christianity) or experiments exploring this accepted world (e.g., Surrealism, Dada, Modern Art, Existentialism, Egoism/Individualism/Anarchism, Deconstructionism, Postmodernism, etc).

From the introduction to Dostoevsky's The Grand Inquisitor by the American Heidegger-scholar and philosopher Charles Guignon:

Briefly put, the issue is this. Either God exists or He does not exist...if God does not exist, then the picture of the universe formulated by mechanistic materialism must be true. But, in this case, given the point of view of modern science (what Ivan calls "Euclidean reason"), the universe consists of nothing but meaningless material objects in causal interaction, effects follows cause according to the laws of physics, people are determined to do what they do, no one is guilty of anything, and so there are no such things as right or wrong, good or bad. Or, more precisely, the ideals of justice, goodness, benevolence, dignity, and so on turn out to be purely human inventions, the results of projecting our needs and wishes onto brute, meaningless matter, and so they are illusions lacking any basis in the order of things.

...Dostoevsky regarded [this] as the inevitable outcome of the perfectionist stance of detachment and moral superiority: the idea that, for higher people, "everything is lawful." [If] "God is dead"...then why not step outside the law and do whatever you want? From this standpoint, morality looks like a suckers game. The paradox [of] Westernized ideals, then, is that its austere discipline of detachment and self-transformation tends to undermine its own moral underpinnings. In the end this form of idealism spawns a self-serving moral nihilism.