Today, most of the defenses of traditional morality in the public square are pretty crappy. A lot of them are negative in formulation, reduced to exposing inconsistencies in the other side’s arguments, or warning of dire consequences if X or Y is allowed.   

Even many of those who generally support traditional morals feel that something is lacking in the political defenses of them.

So what happened? Why does traditional morality have such a hard time defending itself?  

Alasdair MacIntyre attempts an explanation in chapters 4 and 5 of his classic After Virtue.

According to MacIntyre, up until the Enlightenment, morality in the Western world was based upon a traditional Aristotelian framework in which you have 1) human nature with all of its characteristics; 2) an end (telos) that human beings are trying to get to; 3) the morals that help human beings go from point A of their nature to point B of their end.

Aristotle and others in his philosophical tradition believed that people could rationally come to know this human nature, the goal of that nature, and the behaviors and characteristics needed to get there. MacIntyre argues that Judaism, Christianity, and Islam superadded divine revelation to this Aristotelian framework, but didn’t essentially change the framework itself.

But, exhausted by the upheaval of the Protestant Reformation and the religious wars of the 17th century, Enlightenment thinkers such as David Hume (d. 1776), Immanuel Kant (d. 1804), and Søren Kierkegaard (d. 1855) tried to find a new basis of morality – one freed from any overarching, religiously-informed view of man and his supposed purpose in life. They wanted to keep the traditional morals, but to untether them from the Aristotelian framework in which they were originally formulated.

They failed.

In fact, MacIntyre maintains that the Enlightenment project of justifying morality “had to fail.” The traditional morals it upheld were now “incoherent fragments of a once coherent scheme of thought and action.” Ethical behaviors such as acting justly toward other, keeping promises, and entering into marriage were still promoted, but their performance was now no longer connected with an agreed upon goal of human life. Shorn of their original context, traditional morals no longer made sense.

The failed Enlightenment attempt to justify morality thus paved the way for the moral relativism and incoherence of moral disagreements today. For, as MacIntyre writes, “Once the notion of essential human purposes or functions disappears from morality, it begins to appear implausible to treat moral judgments as factual states.”

As a result, we now live in a world where those who tell you to do something may very well not have a good answer to the question “Why?”?