The so-called “Birthers movement” has dominated the news over the past month. In case this posting is read by someone from the distant future–say, a month from now–here’s what this is all about: the birthers claim that President Obama may have been born in Kenya rather than in Hawaii, and hence constitutionally ineligible to serve as President. Although the question was raised during the 2008 primaries by a supporter of Hilary Clinton, it has been embraced by opponents of Obama from the right, and by the crankocracy at large.
This blog is about science, so I’m not going to talk about the history, politics, psychology, sociology or comedy of the birther movement. Instead I want to talk about the role of evidence in this debate, to point out some striking parallels with the role that evidence plays in scientific debates, as well as some striking differences.
So what is the evidence is the birther debate? I’ll keep this brief. Fuller summaries can be found here and here. First, the evidence that Obama is a natural-born citizen of the United States consists of (a) an official “certification of live birth” from the State of Hawaii, (b) statements from current state officials that this document is valid, and (c) announcements of Obama’s 4 August 1961 birth in two Honolulu newspapers. Of these, the first source of evidence is normally regarded as sufficient proof of citizenship.
What about the evidence that Obama was actually born in Kenya? As far as I can tell, only one item of evidence for this claim was put forward to get the birther movement moving. This was a supposed affidavit from Obama’s step-grandmother that she was present when he was born in Kenya. Actually, no such affidavit has been produced to my knowledge. However, there was a recording made of Obama’s grandmother telling one “Bishop Ron McRae” by telephone (with the help of a translator) that she had been present when he was born in Kenya. However, the same interview quickly revealed that she was misunderstood and tried to correct the misunderstanding. Listen to how it unfolded here and here. It sounds to me that when she said she was “present,” she meant to say she was “alive” at the time he was born. In any case, she went on to assert that Obama was born in Hawaii.
That’s it for the primary evidence for either side (unless we were to consider the forged Kenyan birth certificates that were apparently designed to embarrass the birther movement). However, this isn’t the only evidence that has been discussed.
On the birther side, there are numerous claims that are aimed against the evidence of Obama’s U.S. citizenship (not for his supposed Kenyan citizenship). These claims fall mainly into two categories. First there are suggestions that Obama’s Hawaiian documents may be forged or based on false testimony about where he was born. Second, there are allegations (based on faulty
faculty legal reasoning) that Obama’s citizenship is called into question by his having only one native-born American parent, or having been adopted by his Indonesian stepfather.
As for the defense of Obama’s status as a natural-born citizen, the additional evidence, such as it is, is mainly along the lines of “why would Hawaiian officials be motivated to lie about the authenticity of Obama’s birth records?” and “why would anyone have a reason to plant false birth announcements in newspapers?”
In other words, the additional evidence being offered by either side consists principally of challenges to the other side’s evidence.
What does this have to do with science? A lot, actually. Science is committed to testing the truth or falsity of claims about nature using evidence publicly available to independent observers. What is the evidence that science uses? By definition it can be any observation made with our unaided senses, or with a device, such as a telescope or microscope, designed to enhance our senses. Such evidence has the power to convince because it is potentially available for anyone check, to replicate. All you have to do is to look with your own eyes, hold the same fossil in your hand, do the same experiment, peer through the same telescope at the right place in the heavens.
So goes the textbook version of how science works. But in practice there is more to it than that; there is an additional kind of evidence that is perhaps more widely used in actual scientific debates than any other kind. I’m talking about testimony, or the trusted statements of reliable observers. As a practical matter, it would be impossible for any one person to repeat all of the observations or experiments that back up the claims of science. So, vast amounts of scientific knowledge are taken on trust. Like almost anyone who has thought about it, I’d love to know what happened to the dinosaurs to cause them to disappear from the face of the earth around 65 million years ago. Actually, I think I do know–not because I or anyone else witnessed the global cataclysm that afflicted the earth 65 million years ago. I haven’t even met the scientists who have evaluated the geological traces left by this cataclysm and have identified the culprit as an asteroid the size of Manhattan island. (Nor have I met the scientists who have suggested instead that the climatic changes that extinguished the dinosaurs were caused by massive volcanic eruptions in what is now India.) I am in no position–practically speaking–to evaluate the evidence for myself. Instead I have to trust someone else’s evaluation of the evidence.
Why should trust in testimony give me such confidence? After all, the latter-day prophet Rael said that he received a message in 1973 from aliens who explained their role in guiding the evolution of life on earth; the not-so-latter-day prophet Joseph Smith said that he received a message in 1823 from an angel called Moroni who told a story little more believable than Rael’s. Lots of people fervently attest to the truth of one or the other of these stories, which amount to eyewitness testimony. I find both to be nonsense. I don’t trust the testimony.
Why, then, do I trust the testimony of other scientists? The key difference is that the testimony of scientists can potentially be checked, and disproven if it is wrong. In fact, the scientific community has developed an elaborate array of social mechanisms to hold scientists accountable for the accuracy of their testimony. These include (i) the expectation that methods be thoroughly described (so others can repeat them), (ii) peer-review of publications, grant proposals, and tenure applications, and (iii) communities of experts who do have the expertise and opportunity to test claims of other scientists independently.
By contrast, the testimony of the prophets and their followers can’t potentially be checked or disproven. All such religious testimony is based on private, rather than public, evidence. The belief system provides no mechanism whatsoever for independently testing such testimony.
Back to the birther “controversy.” The controversy is being kept alive (in some people’s minds) because, after all, it is not hard to poke holes in testimony, if you are creative enough and are willing to impugn people’s motives. So what if there are photographs of an apparently authentic “certification of live birth:” maybe the photographs or the document itself were faked. The Republican governor of Hawaii, backed by other state officials, has attested to the validity of the birth records, but maybe these officials, motivated to defend the pride and integrity of their state, aren’t giving the matter enough scrutiny, or are just lying. The newspaper announcements were real, but perhaps they (along with the birth certificate) were based on false testimony by Obama’s mother, so she could avoid the hassle of going through a naturalization process for her son.
How to counter such criticisms of the testimony? Unfortunately, I don’t see any way to do it. So long as we have to rely upon testimony by people who, rightly or wrongly, can be said to have a motive to lie (or to deceive themselves), then clever critics can poke holes in this testimony. The critics can then satisfy themselves no matter how weak their own evidence.
Common sense provides a way out. Believing that Obama was born in Kenya and not Hawaii entails a belief in a large network of lies, omissions, and misunderstandings, all of which continue to be maintained across generations by people whose motives otherwise would not be aligned. Believing that Obama was born in Hawaii is a much simpler proposition, entailing far less cognitive dissonance.
This kind of common sense has a counterpart in science, the widely used principle of parsimony, sometimes called “Ockham’s Razor” after the 14th century logician William of Ockham. The principle is commonly stated as, “Entities must not be multiplied beyond necessity.” In science this means favoring explanations that account for existing evidence in the most efficient way, i.e., with the fewest auxiliary hypotheses. Scientists use this principle not as a matter of faith, but because it tends to work. Simple example: it is easier to believe that the earth and other planets orbit the sun than that the sun and other planets orbits the earth, because this one elegant hypothesis (presented to western science by Copernicus) more easily explains the apparent motion of other celestial bodies as viewed from earth, including bodies not known prior to the invention of telescopes.
Ockham’s Razor is just a heuristic, a rule of thumb. It isn’t infallible. Sometimes scientific explanations entail hypotheses of great complication, and are nevertheless true. Sometimes there really are political conspiracies involving elaborate webs of deception. But still….
It can be very frustrating to argue with people who cling to conspiracy theories that require a convoluted–and unparsimonious–narrative in which each new fact or item of testimony is met with a counterclaim about a supposed lie or distortion by someone who has no apparent motive to deceive. It is equally frustrating, of course to argue with people who would deny the moon landings, the Nazi Holocaust, or the guilt of Al Qaeda in the 9/11 attacks.
The frustration arises because these kinds of arguments–and those made by the birthers–ultimately don’t have any concern for evidence or parsimony of explanation. Instead they rely upon one underlying assumption: that people lie.
Edited 5 Nov 2011 to correct one typo.