Update September 2012 – This was one of the sample posts chosen for the podcasting experiment; click below to listen, if you like (it is identical to the text):
There’s a common argument style that crops up in defense of most of the topics that critical-thinking addresses, such as paranormal activity, alien visitation, religion, alternative medicine, psychic powers, crystal energy, divination, astrology, and the health benefits of smearing yourself with feces. And it’s a very simple one, but fortunately many skeptics and critical-thinkers fall for it. Paraphrased, the argument is, “You cannot prove that [insert topic] doesn’t exist/work.” In other words, “You can’t prove that god doesn’t exist!” and “You can’t prove that the planets don’t influence our lives!”
Now, I’ve addressed this before, most especially with the direct fact that one cannot prove a negative – no one can demonstrate that god cannot exist in some realm we haven’t discovered, or that the alignment of planets does not exert a force we have not found a way to measure. Sure, I’ll openly admit it! You won that round!
Except… what was just won? The argument establishes that [insert topic] might be possible, simply because we cannot actually establish “impossible” as a distinct certainty? Think about this for a second: it literally applies to everything that can be imagined. The universe is infinite, to most accounts, but certainly far bigger than we are going to examine in the duration of our species’ existence. The only thing such an argument really accomplishes is the admission that human beings are not omniscient.
Congratulations on that astounding conclusion! I’d award a cookie for this, but only if the debater is less than six years old. To everyone else, this is hardly a stunning victory. As an argument in favor of any particular topic or concept, it’s remarkably pathetic. I’m trying right now, but I haven’t come up with any way that the bar can be set any lower.
You may have noticed that I accentuated might in the phrase, “might be possible,” two paragraphs up. Because even that is a condition of knowledge, not physics. Anything that we have not established as “impossible,” because of our abysmal lack of omniscience, might still be impossible in our universe, due to laws of physics for instance. So we haven’t even determined “possible” as a fixed property.
Alternately, if you avoid the simple two-choice argument of “possible/impossible” and substitute levels of probability, even that dubious victory almost always vanishes. Probability requires evidence of at least factors within the proposed topic, so that something can actually be measured and statistically compared. You cannot rationally propose an order of probability such as “one chance in ten” without knowing how often certain results have actually occurred. Psychic powers, for instance, could potentially have an order of probability if we could measure electrical fields emanating from our brains (they’re actually there, but hundreds of times weaker that the fields emanating from the camera battery charging at my elbow,) and/or a way of detecting such fields by the brain itself, and/or some way in which future events produce or follow a force which is not constrained by time.
What we’re talking about with that is evidence – establishing positive support of a concept, rather than a lack of negative support. But hold on! This is using the concept of mathematics to apply to physical qualities. Does that even work? Is it rational to apply “positive” and “negative” aspects to the existence of phenomena or properties?
Technically, no. There really isn’t such a thing as a negative existence, and as we determined above, no way to prove non-existence. The best we can reasonably work with is “positive” (proven to exist) and “null” or “zero” (not positive.) Therefore, if you lack positive evidence, you’ve only established zilcho.
And that’s the argument. “You can’t determine a quality which doesn’t actually exist for [insert topic], so you have to admit to nothing!” Sure. Whatever makes you happy. Someone can even try this argument while taking tests, and not mark down any answers at all. “Ha! You can’t prove I had a wrong answer!” But I bet I can predict what the final score comes out to…