You can get away with a lot just by asserting strongly enough. I'm thinking specifically of a section from a book I read recently -- Peopleware. One of the PMs on my team got it out of the Microsoft library and gave it to me to read. I didn't take it personally. For a book that's 20 years old, it's remarkably fresh.
In any event, in the book the authors state that for years office space types would assert that cubicles make people more productive. Having heard these assertions as well, I had kind of begun to believe it even though my own personal experience is contrary to that: if I want to be productive, I close my door and glare at people who look like they might want to come in.
But the main point Peopleware makes is that there's no data to back up the "cubicles make people more productive" point. Nobody did a multi-year, multi-discipline study to prove this, the book asserts: they just asserted it. (By now you've caught the circular logic that made me chuckle for a second.)
But the main point that I walked away with was that the power of a confident assertion outweighs a lot. I've seen it happen time and again -- whether it's about which language is more productive or used more or what technology is on the rise or the fall or which company is going to go out of business or be bought. People love to assert things. And what I find really fascinating is that many people love to have things asserted at them. Sometimes just for fun I'll just assert something ridiculous with a straight face just to see what will happen. People who know me just give me a look.
So what ridiculous thing has been asserted at you recently?