Daniel Patrick Moynihan is credited with the comment, “You are entitled to your own opinion, but not your own facts.” Using one's own facts—and too often they are falsehoods—is a distressingly familiar part of American political discourse. What is even more disturbing is how much that falsehoods not only play a role in political competition but derive from that competition. Beliefs, or misbeliefs, flow from political preferences and allegiances, and not just the other way around.

Two different but related processes are at work when this happens. One is the intentional manipulation of beliefs from above, which is most apparent in political campaigns. The other is a form of dissonance reduction, in which members of the public adopt factual beliefs that seem most consistent with their political preferences and allegiances, especially party allegiances.

A recent reflection of these processes is a poll, constructed by Benjamin Valentino of Dartmouth College and administered in April and May by YouGov, that addressed a variety of foreign policy matters. Most of the questions asked for a preference or level of concern. Others asked for a belief, though a debatable belief such as whether a particular foreign country was likely to commit a particular act. A few questions asked for a belief about something on which we know for sure what is true and what is not, and where we thus can definitely identify the misbeliefs. One of those questions asked which of the countries on a list of thirteen have formal treaties with the United States that pledge the United States to help defend the country. The results mostly indicate the well-known general ignorance of the American public about foreign affairs. The country that elicited the most “yes” responses was Israel, which has no such defense treaty with the United States. The one with the fewest “yes” votes (5% of all respondents) was Latvia, which as a member of NATO does have such a formal defense commitment.

Beyond the general ignorance, the party-affiliation effect was visible on this same question. Sixty-five percent of self-identified Republicans mistakenly believed that the United States has a formal defense commitment to Israel, as opposed to 56% of independents and 52% of Democrats. The party discrepancy was more glaring on a couple of other questions. Asked whether Iraq had weapons of mass destruction when the United States invaded in 2003, an astounding 63% of Republicans said yes (in contrast to 27% of independents and 15% of Democrats). There were no follow-up questions about this, and one is left to wonder whether the believers think the subsequent saga of non-existent Iraqi WMD is a big hoax, or that weapons were quickly smuggled to Syria, or what. Maybe enough time has gone by for myth and reality to fade together.

Then, lest anyone think the birther movement is dead, there was a question about whether Barack Obama was born in the United States or another country. Sixty-four percent of Republicans (compared to 30% of independents and 10% of Democrats) believe he was born in another country. Fifty-six percent of the Republicans say they always believe he was born in a foreign country, and 8% say they used to think he was born in the United States but later changed their minds.

All of this is more reason to cringe when we hear falsehoods flow, about government spending or anything else, in the presidential campaign. They are cringe-worthy not only because many people will be voting this year on false pretenses but also because we are seeing the generation of misbeliefs that will be held for many years to come.