5X5 Episode 66

This episode is in the middle of being transcribed by Mark Wade (talk) as of {{{date}}}. To help avoid duplication, please do not transcribe this episode while this message is displayed.

Plausibility in Science

Voice-over: You're listening to the Skeptics' Guide 5x5, five minutes with five skeptics, with Steve, Jay, Rebecca, Bob and Evan.

S: This is the SGU 5X5 and tonight we're talking about plausibility in science. Science is a cumulative effort, which means that all the things we come up with in science, because it's describing the same reality, the same universe, must agree internally, must agree with itself, therefore as we build an ever more sophisticated model of how the universe works we can use that model, those ideas that have panned out in order to test the plausability of any new ideas in science.

?: And it gives us a starting point or, as it were, a point where we can go ahead and begin new sets of experiments based on the principles of plausibility so that we can avoid having to do the otherwise limitless number of experiments that would otherwise be required. It gives us a place to start.

?: How do you determine prior plausibility then? One way is to look at the best, strongest evidence for a given topic. Is the new claim in line with that evidence? If it is then prior plausibility is high. The threshold of evidence is therefore lower for this claim even though it still may be incorrect. Does the new claim *disagree* with the current accepted body of evidence? Prior plausibility is then lower and the old axiom kicks in: extraordinary claims require extraordinary evidence.

S: And what that means practically is that any evidence for the new claim has to be at least as great as all of the previous evidence that says that it shouldn't be true or that it's highly implausible. So you're still comparing evidence to evidence at the end of the day.

?: A really good example of applying the idea of plausibility would be if you think about homeopathy. Homeopathy, as many of you already know, is the belief that by diluting something in water enough that you can get some type of medicinal effect out of it. There is nothing in science today that would consider homeopathy to be plausible. There's no way that we can see so far with our current science to prove homeopathy or even give it a mechanism for it to work the way that it's described.

S: That's right, so therefore we would say that homeopathy is an extraordinary claim. Water, that doesn't have any active ingredient left in it, can not have a complex chemical action. For example, homeopaths...

S: SGU 5x5 is a companion podcast to the Skeptics' Guide to the Universe, a weekly science podcast brought to you by the New England Skeptical Society in association with skepchick.org. For more information on this and other episodes, visit our website at www.theskepticsguide.org. Music is provided by Jake Wilson.