I've started to dislike this phrase. Extraordinary is subjective.
Obviously you can trot out edge cases. The claim that extraterrestrials run the US government is quite extraordinary. But edge cases aren't that interesting. Most claims fall somewhere in the middle, and in that case can be called extraordinary or not based on the personal biases of the claimant. Thus "extraordinary claims require extraordinary evidence" becomes a goal-post-moving fallacy in practice.
Personally I don't consider claims about governments wanting to surveil people, economic systems tending to concentrate wealth, or the dystopian potential of supra-national corporate governance to be particularly extraordinary. YMMV.
The majority of chemtrail reports are doofuses seeing contrails, but the rumor mill may have started around a kernel of truth. I've thought about a couple possibilities:
(1) Cloud seeding, either experimental or operational.
(2) Experiments with the injection of aluminum nanoparticles into the upper atmosphere to increase the Earth's albedo as a potential geoengineering solution to climate change. There's some documentation for this if you Google it, and it might look pretty funky to a ground observer.
(3) Other experiments with spraying nanoparticles, such as for radar reflection or to attempt to simulate difficult radar conditions to test stealth-busting radars.
Folklore and wild rumor often starts around a seed crystal of truth. Note that many of the early chemtrails rumors came from the American Southwest, which is where the black project kids play with their toys.
> The majority of chemtrail reports are doofuses seeing contrails, but the rumor mill may have started around a kernel of truth.
Yeah, I'm perfectly aware that most "chemtrails" are just contrails, but I have a feeling now that it might have started around a quite solid kernel of truth.
You know, I used to post this picture as a joke: http://i.imgur.com/MM9YsTM.jpg. Now I realize it's exactly what the US military did in San Francisco.
After WWII, through at least the early 60s, the US military discounted risk quite heavily. Human experimentation with virtually uninformed consent was not uncommon. Knowledge of the effects of radiation exposure, and diagnostic methods, was limited. And so they tested on poor people and prisoners.
I'm not even saying that they did a wrong thing here (I do believe that there are important experiments that can only work when subjects are unaware that they're participating; I don't have a definite opinion on this particular one) - it's just that it's hard to dismiss something as TFH if even the craziest stories turn out to be rooted in truth.
> I do believe that there are important experiments that can only work when subjects are unaware that they're participating ...
Medical experiments? Sure, those were "harmless" bacteria, but maybe a few people died as a result of the test.
But would you believe that indigent cancer patients were given lethal whole-body x-ray exposures, and then observed (without treatment) while they died?
I was thinking more about social experiments than medical ones. A lot of problems with current social science research comes from telling people they're part of a study. Humans change their behavior when they know they're being watched (not to mention selection bias; people who agree to be a part of the study are often a very specific population subset, on the intersection of people with too much free time and the kind of people who like taking part in experiments). I think we need more studies like that infamous Facebook one (the one which media took and turned into an overblown ethical issue) - tweaking something and observing the dynamic response of the system, without the system being aware that it's being explicitly influenced.
Obviously you can trot out edge cases. The claim that extraterrestrials run the US government is quite extraordinary. But edge cases aren't that interesting. Most claims fall somewhere in the middle, and in that case can be called extraordinary or not based on the personal biases of the claimant. Thus "extraordinary claims require extraordinary evidence" becomes a goal-post-moving fallacy in practice.
Personally I don't consider claims about governments wanting to surveil people, economic systems tending to concentrate wealth, or the dystopian potential of supra-national corporate governance to be particularly extraordinary. YMMV.