In this New Yorker article, Ezra Klein discusses the psychology of groups (including the work of Jonathan Haidt), then points out a problem with political parties trying to think and talk:

According to the political-science literature, one of the key roles that political parties play is helping us navigate these decisions. In theory, we join parties because they share our values and our goals—values and goals that may have been passed on to us by the most important groups in our lives, such as our families and our communities—and so we trust that their policy judgments will match the ones we would come up with if we had unlimited time to study the issues. But parties, though based on a set of principles, aren’t disinterested teachers in search of truth. They’re organized groups looking to increase their power. Or, as the psychologists would put it, their reasoning may be motivated by something other than accuracy. And you can see the results among voters who pay the closest attention to the issues.

Here's another cognitive hurdle for members of political parties:

In a 2006 paper, “It Feels Like We’re Thinking,” the political scientists Christopher Achen and Larry Bartels looked at a National Election Study, a poll supported by the National Science Foundation, from 1996. One of the questions asked whether “the size of the yearly budget deficit increased, decreased, or stayed about the same during Clinton’s time as President.” The correct answer is that it decreased, dramatically. Achen and Bartels categorize the respondents according to how politically informed they were. Among the least-informed respondents, Democrats and Republicans picked the wrong answer in roughly equal numbers. But among better-informed voters the story was different. Republicans who were in the fiftieth percentile gave the right answer more often than those in the ninety-fifth percentile. Bartels found a similar effect in a previous survey, in which well-informed Democrats were asked whether inflation had gone down during Ronald Reagan’s Presidency. It had, but many of those Democrats said that it hadn’t. The more information people had, it seemed, the better they were at arranging it to fit what they wanted to believe. As Bartels told me, “If I’m a Republican and an enthusiastic supporter of lower tax rates, it is uncomfortable to recognize that President Obama has reduced most Americans’ taxes—and I can find plenty of conservative information sources that deny or ignore the fact that he has.” Recently, Bartels noticed a similar polarization in attitudes toward the health-care law and the Supreme Court.

And then there is the problem that opinions without any meaningful basis (that the mandate is unconstitutional) gain legitimacy through the media/internet echo chamber:

"Once Republican politicians say this is unconstitutional, it gets repeated endlessly in the partisan media that’s friendly to the Republican Party”—Fox News, conservative talk radio, and the like—“and, because this is now the Republican Party’s position, the mainstream media needs to repeatedly explain the claims to their readers. That further moves the arguments from off the wall to on the wall, because, if you’re reading articles in the Times describing the case against the mandate, you assume this is a live controversy.” Of course, Balkin says, “if the courts didn’t buy this, it wouldn’t get anywhere.”

These are the sorts of things that pass as political thinking these days. It makes you want to ask people to leave their party affiliation at the door while discussion important issues. But how do you do that, when that affiliation has reached the level of the sacred, meaning that it is not negotiable?