So, "everyone does it"? Not so fast, Republicans. A quick dip into the evidence makes it clear that Mitt Romney's lies were of a scope, magnitude, and brazeneness that is unmatched in modern political history. His first TV ad, back in November 2011, featured audio of Obama saying, "If we keep talking about the economy, we're going to lose." That sounds terrible -- except it's from 2008, and Obama actually said, "Senator McCain's campaign actually said, and I quote, 'If we keep talking about the economy, we're going to lose.'" Romney said that Obama began his presidency with an apology tour, wants to end Medicare as we know it, and didn't mention the deficit or debt in the 2012 State of the Union (he mentioned them six times). Then there were Romney's misguided statements about the Cairo embassy situation, his running mate's untruth-riddled convention speech, and the campaign's blatant admission, "we're not going to let our campaign be dictated by fact-checkers."

What's happening here? We weigh facts and lines of reasoning far more strongly when they favor our own side, and we minimize the importance and validity of the opposition's arguments. That may be appropriate behavior in a formal debate, or when we're trying to sway the opinion of a third party. But to the extent that we internalize these tendencies, they injure our ability to think and see clearly. And if we bring them into the sort of open and honest one-on-one political debates that we'd like to think Americans have with each other, we strain our own credibility and undermine the possibility of reaching an understanding.

A defense attorney presents the best case for his client's innocence in court, but he's realistic with himself about what he believes the truth of the matter is. Too often in political arguments we have drunk our own Kool-Aid. Take, for example, the national debate we had about torture during the Bush Administration. Almost universally, people who thought torture was unjustified also believed it was ineffective, and people who thought it was justified believed it was effective. There are two questions: Is torture effective for increasing national security? (A matter of fact.) If it is, is it justified? (A matter of judgement.) The pursuit of the answer to the factual question was anemic because most partisans appeared to assume the answer that supported their moral judgment was correct.

A recent report on three psychological studies by professors from the University of California, Irvine confirms this bias, and points out that it's pervasive across a wide range of human situations. Where our moral judgements come into conflict with evidence, we look for ways to dismiss and minimize the evidence:

For example, many political conservatives believe that promoting condom use to teenagers is inherently wrong. This deontological intuition conflicts with consequentialist sensibilities, however, if one also believes that condoms are effective at preventing pregnancy and sexually transmitted disease (STDs). Individuals can resolve this conflict by becoming unskeptical consumers of information that disparages the benefits of condom use (e.g., their prophylactic effectiveness) or enhances its costs (e.g., encouragement of promiscuous sex). [...] Analogously, liberals who feel moral disgust toward the death penalty should be prone to believe information emphasizing its ineffectiveness at deterring future crime or the risks of wrongful execution[.]

It's hard not to read that and think of pundits from opposing political teams arguing on cable television for low-information voters. But cherry-picking facts while trying to persuade someone to take our side or while engaging in a debate is one thing. It's something else to do it while reasoning for ourselves. And yet it seems that our brains are wired to do so; it's not a phenomena brought on by soundbite culture.

While individuals can and do appeal to principle in some cases to support their moral positions, we argue that this is a difficult stance psychologically because it conflicts with well-rehearsed economic intuitions urging that the most rational course of action is the one that produces the most favorable cost-benefit ratio. Our research suggests that people resolve such dilemmas by bringing cost-benefit beliefs into line with moral evaluations, such that the right course of action morally becomes the right course of action practically as well. Study 3 provides experimental confirmation of a pattern implied by both our own and others' correlational research (e.g., Kahan, 2010): People shape their descriptive understanding of the world to fit their prescriptive understanding of it. Our findings contribute to a growing body of research demonstrating that moral evaluations affect non-moral judgments such as assessments of cause (Alicke, 2000; Cushman & Young, 2011) intention (Knobe, 2003, 2010), and control (Young & Phillips, 2011). At the broadest level, all these examples represent a tendency, long noted by philosophers, for people to have trouble maintaining clear conceptual boundaries between what is and what ought to be (Davis, 1978; Hume, 1740/1985).

The studies further show that this effect is stronger in well-informed, politically engaged individuals. The more information we have, the higher our propensity to cheat with it. I've been talking to a lot of people on both sides of the election, and the thing I'm often struck by is an inability to find any validity in the opposing side's arguments. By blocking our ability to have meaningful conversations, this effect is actually harming political discourse.