I think the quote is alluding to capital 'S' scientist rather than a particular group of humans. In theory a Scientist's cause to be correct, while human scientists want to be right.
It's folly to suppose that they're not prone at all, but not so foolish to suppose either that their training makes them less biased, or that being less so biased makes people more likely to become scientists.
-2sediment
Yeah, the only thing I don't like about the quote is that it has an unappealling us-vs.-them quality to it, as if the divide between rational people and irrational were totally clean-cut. Posted it regardless because of the nice turn of phrase at the end.
The history books I have read do not strongly support this assertion. E.g. WWII was a product of Hitler's personality and Hitler's false predictions about how e.g. Britain would react to an invasion of Poland.