It ended, as these things always do, with mutual frustration. Linker decided that I, a traditionalist conservative, believe gay marriage should be illegal because ... I believe it should be illegal. And I reached the same conclusion about his support of same-sex marriage. To Linker, my argument looks like faith-based special pleading. Likewise, his rationale struck me as little more than emotivism -- the idea that something is true because it feels right. We talked past each other, not only because neither of us can agree on what constitutes the Good, both public and private, but also because -- indeed,...