By Steve Cuno
Rule number one of practical skepticism:
It is not prudent to accept a big claim unless there is evidence to support it.
In the movie Dumb and Dumber, Jim Carey’s character’s love interest tells him that the chance of a romance between them is “… like one out of a million.” Encouraged, Carey replies, “So you’re telling me there’s a chance!”
Ha ha. No one really thinks that way.
Well, some do.
When someone points out that there is “no evidence” to support a claim, you can bet that someone else will pop right up and say, “That’s not the same as ‘disproved,’ so the belief might be true.”
Don’t fall for it. Whoever says that is misled or toying with you.
Responsible scientists, skeptics, and rationalists avoid absolutes. “No evidence” is about as close as they get to “no way.” Do not take “no evidence” to mean “quite possible.” Take it to mean, “In the extremely unlikely event that something comes along that turns our understanding upside down, we’d better be prepared to accept it.”
Sometimes scientists go to ridiculous lengths to make the point. Consider the old saw, “In science we say that the sun MIGHT come up tomorrow.” Come on. No scientist is worried that sunlight won’t greet us in the morning. It simply means that if one day we awake to a sunless sky, we shall have to acknowledge it. Of course, we’d have to hurry. We wouldn’t be around much longer.
On a personal level, the point is easily illustrated if we get a little silly. Tell me that you own a garlic clove that sings aloud “The Star Spangled Banner,” and I will ask for a bit of evidence. No matter how sincerely you believe, no matter how much passion the idea stirs within me, and no matter how highly I esteem you, if you have no evidence to support your claim, it would be irrational—in fact, irresponsible—of me to walk away saying, “Still, I suppose it’s quite possible.”
The point gets harder to see with claims we hold dear.
“No evidence,” responsibly wielded, means it is prudent not to accept a big claim unless there is reasonable evidence to support it. You are, of course, free to believe anything you choose, evidence or no evidence. But please resist the urge to claim that “no evidence” is on your side.
Edited, with permission, from this original piece.