Growing up with and around hippies, I was exposed to a lot of pseudoscience, so I had to develop a set of metrics to differentiate between science and pseudoscience. Many of them had to do with considering the reliability of the source, (if I heard this from some guy named Moonbeam at a Rainbow Gathering who can barely stand up straight: Probably not too reliable), but a few are more useful, and have stuck with me over the years. The main one has to do with mechanism.
One of the most pernicious pseudosciences I encountered as a child was astrology. It was near universal, and generally had tons of anecdotal evidence. When I’d try to argue it, or express skepticism, it would be dismissed. “Oh, you’re a Capricorn, of course you’re going to be a skeptic.” Didn’t help that I was a child, either.
After years of this debate, I eventually evolved an effective argument: Astrology lacks mechanism. Almost no one I discussed it with had any answer when asked HOW it affected people’s personality and fortune. The few that did respond generally just hesitantly threw out gravity or some other easily falsifiable answer. (Occasionally I’d get “magic” as an answer. I learned to just walk away, then.) Asking someone what the mechanism is for something is a handy metric for gauging both how plausible it is and how well yet understand it. (Simply asking how something works is just fine for lower hanging fruit).
Eventually, I learned to just throw out the mechanism question at any and all pseudosciences. Homeopathy is a good target for the question, it falls apart really quickly. Intelligent design advocates usually refuse to answer the question, but it gets very entertaining when they do.
It doesn’t always work. Many people advocate bad science or unproven science over pseudoscience. With anti-vaccination folks, for instance, there is a laid out mechanism for how vaccinations cause autism. It’s a completely false one, since vaccinations DON’T cause autism, but you still have to fight these things with education and information.
Then you have areas with lots if conflicting evidence, ranging from genetic engineering and GMOs (two HUGE cans of worms, I avoid discussing them with strangers) to herbal medicine (lots of studies with conflicting results, and each treatment needs a separate study on top of that). These areas have room for legitimate scientific debate, so just jump right in. The mechanism metric can help a little bit here. Someone who hasn’t done their research will generally not have any idea how whatever it is they’re supporting/opposing does whatever it is supposed to do, or haven’t been able to find anything.
It’s not a universal metric, but it’s usually a handy addition to any intellectual portfolio. Also, just saying, The Mechanism Metric would make a sweet band name.