The passion surrounding the so-called “social issues” in American politics, from reproductive rights to gay marriage, is exacerbated by the fact that to some degree “the issue is not the issue,” as the Sixties slogan held. In other words, what is really at stake is not merely the nominal subject of the debate, but also a clash of worldviews.
The United States, like other offshoots of Europe and Europe itself, is the heir to three distinct moral systems: custom, creed, and contract.
Custom is the source of one kind of traditional morality. What is right and what is wrong is determined by tribal tradition, as passed down by one generation to the next.
While customary morality in one form or another is as old as humanity, creedal morality — the ethical system of organized, scriptural religions like Judaism, Christianity and Islam — is only a few thousand years old. Writing is a technology, and there could be no scriptural religions until that technology had evolved. Furthermore, scriptural creeds require at least some of the population to be literate. Only agrarian or industrial societies have sufficient surplus to support a specialized class or caste of clerics to serve as the guardians and interpreters of the sacred texts.
More… “The Clash of the Three Moralities”