A Christian nation?
p1) The United States of America is a Christian country.
(p2) Christianity abhors usury.
(p3) Christian countries must not permit anything abhorrent to Christianity.
(C ) Therefore, the USA must not permit usury.
Suppose (p1) means “Christians comprise at least a plurality of American citizens.” On this weak reading, the argument derails, even if we grant (p2) and (p3). So what if a majority of Americans are Christians? What matters is whether a majority of Americans vote to ban usury and whether the proposed anti-usury legislation is constitutional. The weak version of (p1) doesn’t do any work. If that’s all the “Christian nation” claim amounts to, the argument reduces to a civics lesson.
After looking at a stronger version of (p1), she turns to a medium version:
She's correct that medium (p1) is too vague, but I don't think that her reading of the medium (p1) is the one that best tracks Christian Reconstructionist logic. I've noticed that Reconstructionists make recourse to medium (p1)': there's a 'good fit' between the freedoms granted us by the constitution and the sense of responsibility honed by being Christian. Hence the constant repetition of banalities like 'with freedom comes responsibility' accompanied by a few scattered quotes from founders that imply that our freedoms could only be possible in a nation in which the people are Christian.
Here’s a medium strength (p1) that Christians often deploy when pressed: “The constitution is based on Christian values.” This claim is too vague to sustain our sample argument.The values of the constitution are consistent with many of the values of Christianity, but also with the values of many other religions and many secular ethics.
The position would be that there have to be extra-legal supplements of the law in order to integrate the individual into the society and to preclude a collapse into Hobbesian chaos.
One could see the same meme at work in the clash of civilizations, and particularly in the work of Samuel Huntington, who has the same basic thesis (except that he specifies further, and locates the supplement in the traditions of WASP Christianity). Christian Reconstructionists argue from an express Natural Law position, while Huntington's version is a bit more sociological, but they're functionally identical: democracy can't survive on its own, and needs some institutional or religious buttresses.
Medium (p1)' is still rubbish as far as truth-value goes, of course. I'm perfectly fine with the necessity of a value-based supplement, but the specificity of Christian Reconstructionism is way overdetermined. In other words, I suppose the objection to medium (p1)' is the same as the objection to medium (p1): " The values of the constitution are consistent with many of the values of Christianity, but also with the values of many other religions and many secular ethics."