Until the smallest and easiest bit of logic or reason is applied.
1. I had a guy who insisted that softball hitters were much more skilled than baseball hitters. There was lots of theory about how there is less time to react and the ball has more curve etc. You can even google it: This guy wasn't the only clown to make the claim. But it all wilts under one question: If softball hitters are more skilled and they are mostly women, how come there isn't a single woman in the MLB? The pay is huge for players that can hit and there is no rule prohibiting women from playing.
2. This is an old one from my youth and so you may not be able to find anyone claming it now: Back then, people would often claim that guns will not work in space. The people who made the claim often felt that it was deep somehow: Futuristic Man will have no need for such primitive and backward things etc. I never understood the basis for even thinking they wouldn't work: The fuel and oxidiser are contained within the cartridge--chemical reactions don't need gravity.
Kate Walsh O'Beirne R I P
36 minutes ago