More on dogma

Something else occured to me recently about the pragmatic/ideological divide discussed here (and elsewhere, in response to Jonathan Chait's column in The New Republic). Let's look at the issue of gay marriage. Conservatives generally take it as self-evident (wrongly, in my opinion) that gay marriage will destroy traditional marriage, and in doing so, weaken our society. This isn't really based on any evidence, and I think it's rather rediculous to think that allowing two people who love each other to get married can be a bad thing, but that's not really the argument I'm getting at here. The point is, let's say conservatives are right and society crumbles into disrepair as a result of allowing gay marriage (again, I don't think this will happen, but bear with me). Would liberals then reverse their position on gay marriage because the "ends" are undesireable? Or would they stick to their guns and say that the right to marry whomever you please is a fundamental freedom in our society, and cannot be infringed upon, even if the unintended (and perhaps indirect) consequences are negative? It seems to me that they would (and should) defend gay marriage because it is morally, to their eyes (and mine) the only defensible position. This would be an example of sacrificing pragmatism to dogma. And maybe that's not always such a bad thing.