"When you (or somebody else) finally has the good idea, you feel very stupid for not having seen it sooner." — H. M. Georgi, "Grand Unified Theories" in The New Physics
One evening two men went to a social club event. One of the men had quite a bit of alcohol, the other stayed entirely sober.
Each man drove home in his car in the darkness. The sober man got distracted and drove off the road and smashed his car into a tree, but he was not hurt.
The drunk man weaved around a bit on the road and almost hit a car, a dog, and a mail box, but kept it together and made it home without scratching his car. He even managed to stumble unhurt into bed before passing out.
The men at the social club analyzed the event. The concluded that in the interest of safety, every man would be required to drink a minimum of two alcoholic beverages at all future events.
Obviously this is a false parable, but it illustrates some very interesting aspects of reality and the human mind. In shows the difference between anecdotal evidence and statistics. Also that drinking is preferable to sobriety, until it isn't.
Statistically driving drunk is a bad bet. Take a sufficiently large sample and a trend will appear. Not everyone who drives sober drives safely every time. Not everyone who drives drunk gets in a wreck every time. But the frequency of accidents is quite a bit higher for drunk drivers than for sober drivers. The frequency of accidents also climbs as the amount of alcohol measured in the blood climbs.
I originally made up this parable to explain to my friends why one of my friends did not believe in global warming. Most of my believer friends have only the vaguest idea of how statistics work. That does not prevent them from sharing statistics that confirm their beliefs, even if it is easy to show the statistics are falsified. Math is just not a strong point with them. Let's call them artists, rather than math disabled.
On the other hand my global warming denier friend is a very capable guy. He is good at logical argument, at accounting, and at statistics. He knows more about the history of temperatures of the ancient earth than I do. So what are the chances that he is wrong and the artists are right?
We can know he is wrong by looking at the work of people, scientists, who know even more than he does. Those scientists have vast arrays of data available for analysis and know what can go wrong when data is collected.
We know he is wrong because we can step into a greenhouse during a sunny day in winter and notice it is warmer than outside. We can check (should we have the time and interest) the spectral characteristics of sunlight, of carbon dioxide, and of the radiation of heat from the earth, and see that carbon dioxide is indeed a greenhouse gas. And we can measure (in a home lab, if you have the money for equipment and the skill) the level of carbon dioxide in the air, and compare it to older measurements. And of course there are all those thermometers the scientists have set up around the world, starting in the 1700s.
But for a lot of stuff is even harder to distinguish between anecdotes, belief systems, and factual statistics. Recent studies showed many science experiments are difficult to reproduce, and that difficulty seems to be driven by mental (and ethical) problems of the scientists. In other words, Publish or Perish drives the survival of the best liars. In particular it seems like the entire profession of Psychology is run by nut cases. When specifically asked why their experimental techniques were so bad, most psychologists did not even seem to understand there was a problem. Yikes. [See How Scientists Fool Themselves]
Of course my global warming denier friend would take this information and say exactly: my global warming denier scientific minority has it right. Your ecology-warped green scientists are misinterpreting the data.
Even stay-at-home paranoid Internet mavens don't have time to check every fact. Politics and many other professions depend on lying as a basic tool. Yet we need truth or we will suffer bad consequences.
Fortunately most lies don't pass the basic smell test. My first order guess is that the scientists are right and the theologians are wrong. Scientists are not always right, and theologians are not always wrong. But it you drink the theological kool-aid, you are going to crash into reality at some point.