The question presupposes a classical view of "rational argument," namely the use of classical logic (e.g., mathematical logic) in the service of self-interest.

But that is not how real rationality works. Political argument starts with moral framing - what is assumed to be right, not wrong or morally irrelevant. Conservatives and liberals differ on what is right. Real rational argument uses the logic of frames and metaphors, as well as the use of emotion in setting goals. For example, poor conservatives may care more about their moral identity as conservatives than about their financial self-interest. This is not "irrational;" it is a matter of what is most important to a given individual — moral identity or financial self-interest.

George Lakoff Progressives Need to Use Language That Reflects Moral Values