The argument from authority is considered one of the informal logical fallacies. An informal fallacy is roughly speaking one which occurs when someone is making a non-deductive argument. But enough with the logic class. Why is an argument from authority bad? I think when we really break things down it is not arguments from authority that are bad, but instead arguments from false authority. As a student, I recently had this difference driven home to me in two of my classes.
It is not uncommon for upper division science classes for professors to invoke basic principals or ideas from other scientific disciplines. I think this is particularly true in two fields as intimately related as chemistry and astronomy. While this connection might not seem obvious at first, it is a deep connection and may be the topic of another post. This brings me to my introductory astrophysics course this last fall. We were deriving basic equations to describe the interior of stars and as a starting point we took the ideal gas law. I asked my professor under what circumstances the ideal gas law was valid and they replied by saying it is valid so long as the substance in question is a gas. If you do some research you can find that this is not quite true. For example under high pressures you need to use a more complex equation of state such as the van der Waals equation. Analogously, my chemistry professor at the start of the semester, when discussing the diversity between the planets, claimed that the Moon and Mercury both don't have days. This would mean that they both would have a light side and a dark side. "The dark side of the moon" is certainly a great rock album, but it is also one of the more common myths in astronomy. In reality the Moon as a diurnal period of about 30 days and Mercury's is about 178 days.
So what can we conclude from this? Should we simply say that my professors are bad authorities on which to base knowledge? I don't think this is the case. Instead I think that we need to take the more nuanced position and say that no one, no matter how educated, is an authority in everything. My astronomy professors are strong authorities in their sub-fields of astronomy but beyond that, they likely only have the knowledge of an informed non-expert. If we really want to understand something, we should look to the people who have devoted their life to studying that particular thing or better yet, try to find a general consensus of the scientists who work in that discipline. For as much as we would like to, I don't think we can ever truly escape arguing from authority. So instead of trying to avoid the matter altogether, let's use it as a tool to expand our own knowledge and teach those around us.