We’ve talked about polls saying 27% of Republicans think Barack Obama was not born in the United States. What can we infer from that? Let’s assume that this significant following of the idea is some measure of its truthfulness, so on a scale of 0 t0 100 (in a Republican world), the truth of the claim Obama was born in Africa is “27”.
About half of Republicans surveyed, almost twice as many as believe Obama wasn’t born in the US, also believe that the Troubled Assets Relief Program (TARP) was enacted under the Obama administration, not Bush. This is, of course, historically false.
So, logically, we may assume that the probability of Obama being born in Africa is less than the TARP being enacted under his administration. Calibrating our 0-100 Republican belief scale in to real probabilities, we see that the probability of Obama being born outside the United States is actually zero.
[Note for the humor impaired: I don’t really believe that this is a rigorous mathematical argument.]
Update: One of the commenters here asked for sources for the figures used in this article. They come from the piece Building a Nation of Know-Nothings in the New York Times.
The other thing that has come to light is that some mathematically disinclined persons didn’t understand the argument. I don’t really want to try to explain it to folks who wouldn’t get it no matter what I said. For those who can:
I start with the assumption that the more Republicans believe something to be true, the more likely it is to be true and so the function mapping Republican belief to real probability is a monotone non-decreasing function. Given the one known point on the function (50, 0), a non-decreasing function would have a truth probability value of zero for every belief percentage less than 50 and therefore the value for 27% (the number that believe Obama was born outside the US) must also be 0. Once 51% of Republicans believe Obama was not born in the United States, we’re in trouble.