"An extraordinary claim requires extraordinary proof."—
Carl Sagan, quoting Marcello Truzzi,
following Douglas Hume
in the tradition of P-S Laplace
So early scientists were right to demand strong evidence for cosmologies denying that the Earth was the center of the universe, and Darwin was right to collect considerable data before publishing a theory that species evolved over huge stretches of time; and there were good commonsensical reasons to doubt that unseen and for a long time unseeable particles cause diseases, or continents can move; and there remains good reason to require extraordinary evidence for claims of ESP or levitation or telekinesis or alien abduction or alternative-medicine miracle cures.
There are more things in heaven and on earth than are dreamt of in any philosophy, and, indeed, as J.B.S. Haldane said, with no reference to sexual preferences, "the Universe is not only queerer than we suppose, but queerer than we can suppose." Very weird shit happens, yes, but not often; the everyday world is mostly pretty banal, and well, everyday, and we should be suspicious of any specific claim for the truly unusual. A few seemingly wild claims hold up; most don't.
That much is easy, as a general principle, at least for those of us not convinced that a correct premonition or two proves something significant or that the Silicon Creatures from the Tau Ceti System abducted them. We may come down one way or another on whether some case has been proved, but we can agree to demand strict scrutiny of the evidence.
Or we can agree if we allow no "special pleading" and decline to, for a relevant example, condemn out of hand testing purported scientific claims in Genesis against scientifically-collected data, or (for a balancing variety of special pleading) if we assert that scientific claims should never be challenged for their implications, if true, for ethics, human happiness, or the law.
A claim teased out of Hebrew Scriptures on the age of the Earth is testable, and if the geologic evidence indicates a world billions of years older than the Scriptural claim, that Scriptural dating has been, as a scientific claim, falsified.
An attack on the notion of free will could begin with noting free will as a strongly strange idea to start with — some hypothetical force beyond the usual laws of nature — and moving on to demonstrate that free will is an increasingly unnecessary hypothesis in explaining human behavior. Denial of free will, however, is a problem pragmatically: in terms of getting on in the world, we need to act as if we are free, and take responsibility for our actions.
Denials of free will aren't extraordinary in the sense of implausible, but they are extraordinarily mischievous in practical, pragmatic terms; so they require very strong evidence: "extraordinary proof."
Anyway, as a general rule, the closer we get to human affairs the greater should be our skepticism about claims extraordinary enough to make it into the newspapers, and I want to suggest a couple of human-sphere modifications to the good advice from Carl Sagan and his predecessors.
The more sensational or even just newsworthy the claim, the more we should demand strong proof; the more an extraordinary claim reinforces completely ordinary stereotypes about people or repeats exciting folklore, the stronger should be our demand for strong proof.
As I write, one of the SHOCKING NEW TRENDS (THE MAIN-STREAM MEDIA IS [sic] IGNORING)!!! is "the knockout game," especially a version where Black male teens run up and slug some random White person on an urban street.
Yes, Virginia, we do have assaults in America, more than our share, especially in failing cities; and some of it is random and felonious assault and serious battery and some is Black on White. But a trend, an increase in occurrences — some new problem to Fear and View With Alarm!? Not really.
So let's break this claim down and examine it.
Adults have been complaining about wild, violent, over-sexed, ill-mannered, irresponsible kids since at least the time of Satire 14 of the Roman satirist Juvenal (who thought, by the way, the complaining parental generation way worse than their kids). In English, the classic statement is from early in the 17th century, by an old Shepherd in Shakespeare's Winter's Tale: "I would there were no age between sixteen and three-and-twenty, or that youth would sleep out the rest; for there is nothing in the between but getting wenches with child, wronging the ancientry, stealing, fighting" — and then the Shepherd moves on to more specific complains about "these boiled brains of nineteen and two-and-twenty" out hunting in a storm and scaring off a couple of his sheep (3.2).
Indeed, too large a cohort of unmarried, "masterless men" in their twenties or "youth" are a problem, or a set of problems, for societies, especially in cases where young men have just been released from official military service and have time on their hands, and weapons in them — and no better opportunities for advancement than banding together and raiding the countryside: a major problem in Europe of the late Middle Ages and Early Modern periods, with analogies today.
On the other hand, there's that long history of societies' alternating between sentimental celebration of "youth" and a mean-spirited denigration of the young. Add to this the banal fact of anti-Black racism in American history and to that unholy combination add that stories of dangerous young Black men can serve high-stakes political agendas.
If the young and Black and male are sufficiently malicious and vicious to attack total strangers for entertainment, the soundest and most reasonable investment in them is in the criminal justice system for keeping them under control. So we old folks can feel just fine spending on prisons and prison-like schools for them and not much on their health care, nutrition, actual education and/or job training, and well, "general welfare." Which leave more money for old folks and our increasing needs.
Be very suspicious of such claims.
Out in the various media-spheres there are conscious propagandists and political operatives and semi-conscious reporters and gullible bloggers and e-mailers and tweeters and posters. And such people innocently or highly guiltily can take kernels of truth and wrap them in thick layers of bullshit, and we get urban legends like an epidemic of random muggings — or stories of snuff films or pink-cheeked country girls kidnapped into White Slavery or legions of spat-upon troops returning from Vietnam.
Extraordinary and politically useful claims require strict scrutiny and a lot of proof.
Politically useful claims that reinforce well-established negative stereotypes may indeed by true — but they require even stricter scrutiny and proof.
So if you're told that slavery and sex trafficking have never been worse than they are today, that schools have never been more violent or that college campuses have developed cultures of rape — step back and ask to see the numbers and the definitions. It is an extraordinary claim that slavery today is remotely on the scale of slavery in the ancient world or in the time of the perfectly legal and totally horrendous Atlantic slave trade of the 16th into the 19th centuries. And the Atlantic trade was just one of the slave trades; slavery in the American colonies and later United States was just one of the systems of slavery: slavery enforced by law, with terror and rape built into the system.
Moving down the scale from the horrific, it's an extraordinary claim that schools today are more violent than in the past: the days when schoolboys were routinely paddled, tawsed, caned, birched, and/or just occasionally slapped around. We still have too much violence in schools and too many school shootings — but we need to scrutinize carefully scary claims and remember that state-sanctioned violence (and relatively mild and occasionally useful violence) is still violence.
Finally, for me to court some trouble, consider two extraordinary and newsworthy claims in reports on the high incidence of college rape found in at least one study, that of the New York State Coalition Against Sexual Assault, and the assertion that "48.8% of college women who were victims of attacks that met the study’s definition of rape did not consider what happened to them rape" (Bureau of Justice Stats. “Sexual Victimization of Collegiate Women” 2000, US DOJ).
If the claims are for events sufficiently out of the ordinary to get heavy coverage in the media, if the claims are politically useful to one cause or another, if they fit neatly into your political views and those of a number of other people, if they reinforce negative stereotypes and get you scared or angry and/or upset — for one thing, switch the channel from Fox News, but as a larger operating principle: demand strong evidence.