(Original series M:I image used, since I don't feel like promoting Tom Cruise or his nonsense.)
Welcome back to "Doggerel," where I ramble on about words and phrases that are misused, abused, or just plain meaningless.
"Impossible" is a word that woos like to use to describe skeptical explanations for "paranormal" phenomena. They also like to force it into the mouths of skeptics.
Of course, there are some contexts where things really are impossible.
The first that comes to mind is the category of "logically impossible." Some things with mutually exclusive terms fit into this category, like "round squares," "acid with a high pH," and "supernatural effects." One old question in theology is "Can God make two mountains without a valley in between?" Some theologists have gotten around this question by limiting the deity's "omnipotence" to being able to only do things that are logically possible.
The second category that comes to mind is mathematical impossibilities. In math, it is possible to prove a negative, though MarkCC probably knows a heck of a lot more about the details than I do. It is, for example, impossible to "square the circle," that is, to construct with a compass and straight edge, a square with the same area as a given circle. Something about requiring to find the algebraic value of pi, which is a "transcental number," and thus not algebraic. Time Cube Guy has claimed that he can square the circle, but my gut says he cheated by redefining pi as 3.20.
Onto the doggerel:
One of the claims I often hear from woos trying to defend their beliefs is that it's "impossible" for it to have happened any other way. "It's impossible for a trickster to do what John Edward does." "There's no way a trickster could have fooled me. I'm too smart for that." "It had to be an alien space craft. It couldn't possibly have been anything else." "Crop circles are alien telegrams. There's no way human beings could make such things."
One of the problems in these examples is that the woo is essentially claiming infallibility. People aren't perfect. There are all sorts of logical errors we can perform on ourselves, and we can't afford to think for a moment that we're immune. Science is fallible, and scientists are keenly aware of that: That's why replication and tightening controls are so important. If we make a mistake, we should have an error-correction process.
Another problem is that some of those quotes underestimate the ability of other humans. I've heard that if someone went to South America and claimed aliens built those pyramids or drew the Nazca Lines, he'd be deemed a racist by the local populace. And they'd be right: It's just a matter of whether that person is racist against the ancestors who constructed those wonders (they're perfectly explanable, but still wonderous), or against the human race in general.
I suspect the latter problem is another case of projection: Just because the woos aren't clever enough to figure out how the ancients could have done it with simple tools does not mean the ancients weren't clever enough. The people of those bygone eras were just as clever as we are today. They just didn't have the massive knowledge base we have now.
Next is the straw man use: Woos like to think that we believe their treasured beliefs are impossible. In our uncertain world, there really isn't much we can prove impossible. A proper skeptic merely has "negative confidence" in fairy tales: We have an absence of evidence, and plenty of reason to doubt. We don't have certainty, and that's a good thing.
We don't have to prove that something is impossible, and frankly, I have no desire to do so. The burden of proof is on the advocate: If you want to prove that your brand of woo is possible, do so. Don't make stuff up about our position when we refuse to take your word on faith alone.