Anyone who has a critical mind and who attended college long enough, knows not to trust textbooks. They are full of mistakes. Because textbooks tend to copy each other, you cannot even trust a fact that appears in multiple textbooks. Mistakes reproduce.
Some mistakes are conceptual. For example, hardly anyone ever needs calculus over continuous domains, but this still get taught as if nearly everyone needed it. But many mistakes are also factual.
This is made worse by the fact that human being a very sensitive to arguments from authority: if someone important said or wrote something, it must be true, surely? And influential people are not immune to this fallacy, so they sometimes fall like dominoes, quickly embracing the wrong ideas… leaving all of us stuck with a mistake.
From at least 1921 up to 1955, it was widely believed that human DNA was made of 24 chromosomes. This came about because a distinguished zoologist called Theophilus Shickel Painter estimated that this must be the case.
Then, in 1955, a relatively undistinguished research fellow (Joe Hin Tjio), who did not even have a PhD at the time, recognized the mistake for what it was and published a short paper in a relatively modest journal that dared to contradict the established wisdom.
This was enough, in this case, to shift our view, but… think about the fact that there were countless researchers at the time that were better equipped, better funded and more established. None of them dared to question the textbooks. It took someone like Tjio.
There are countless such examples, but we are quick to dismiss them as they do not fit well in our view of the world. Yet I think we should always keep in mind Burwell’s famous quote:
“Half of what we are going to teach you is wrong, and half of it is right. Our problem is that we don’t know which half is which.” (Charles Sidney Burwell)