I've long argued that political disagreements often result less from difference of opinion than from differing notions of the facts. There are a lot of bogus ideas floating around across the political spectrum.
I just saw a remarkable example of this in the results of a recent survey from Public Policy Polling, an outfit based here in North Carolina with a pretty good track record. (This link takes you to a 138-page PDF with the complete results. See in particular questions 28 through 30.)
Some 572 "usual Republican primary voters" (which I think means people who say they usually vote in Republican primaries, a group commonly called the "Republican base") were asked whether President Obama and Senator Ted Cruz (R-Texas) were born in the United States. Obama was of course born in Honolulu and Cruz in Calgary, Alberta, Canada. The reported margin of error is 4.1 percent. The disappointing results:
Only 29 percent of the Republican voters surveyed correctly said that Obama was born in the U.S. versus 44 percent who said that he was not. (The rest indicated that they weren't sure.)
In addition, only 22 percent correctly said that Ted Cruz was born outside the country versus 40 percent who got it wrong.
A few years ago Hawaii officials released a photocopy of Obama's original "long-form" birth certificate, which is bound into a volume in a vault in the records office in Honolulu. The copy was formally certified by the head of the office, who publicly expressed hope that this would finally put the matter to rest.
It's also worth noting that both of the daily newspapers published in Honolulu in 1961 reported Obama's birth in their vital records columns. (Back then it was routine for newspapers to publish such listings, which were supplied by government offices.) These papers are archived on microfilm in public and academic libraries all over the U.S. and in other countries. And why in the world would his young mother, a not-very-rich student, have spent a huge amount of money to travel overseas to give birth away from family and friends? In short, there's no way Obama wasn't born in Hawaii.
Ted Cruz was born to an American mother and a Cuban father, but unlike Obama he really was born outside the U.S., specifically in Calgary, Alberta, and did not move to the United States until he was four years old, as he has himself confirmed. Because his mother was American, he was a natural-born U.S. citizen from birth despite being born in another country. His place of birth made Cruz a Canadian citizen as well, but last year he formally renounced his Canadian citizenship to deal with suggestions that this might disqualify him from running for president.
(Incidentally, you might wonder if he also inherited his father's Cuban citizenship, but from what I've read, under Cuban law he did not.)
It's a little discouraging that in both cases the Republican voters answering correctly were greatly outnumbered by the ones getting it wrong, but at least enough people admitted not knowing that the fraction in error did not reach 50 percent.
Another disappointment: When asked in the same poll whether they believed Barack Obama was a Christian or a Muslim, a solid majority of 54 percent of the Republican voters surveyed said that he was Muslim, another 32 percent said they weren't sure, and only 14 percent identified him as Christian. There is of course not the slightest evidence that Obama is a Muslim and quite a lot that he's a Christian.
Incidentally, I don't mean to suggest that misconceptions are found only on the right-hand side of the political spectrum. Democrats seem about as likely as Republicans to have misconceptions about Social Security, for example, and while I might be mistaken, my impression is that anti-vaccination types are a bit more common on the left.
Update: Or maybe not. While there are for example concentrations of unvaccinated children in politically left-leaning areas of California, I've also been reminded that some Republican presidential candidates in the current campaign (see e.g. this later post) and the last (Michele Bachmann being the most obvious example) made demonstrably false assertions about vaccines, something I can't recall hearing from a major Democratic figure. If anyone knows of an opinion survey showing cross-tabs for political affiliation and mistaken beliefs about vaccines I'd be interested in learning of it.
Also, lots and lots of people have seriously wrong notions about the views of people outside their own groups. For example, a lot of progressive Democrats seem not to realize that many Republicans were just as outraged as they were about the government bank bailouts initiated by the Bush administration in the latter part of 2008.
(Updated 2015 Sep 6 and Sep 12 for clarity and to remove some excess verbosity and a dumb typo and Sep 20 to acknowledge some uncertainty in my impression that anti-vaccine nonsense is more common on the political left.)