Is there a term for the tendency of people who are experts in one area to incorrectly assume they have a higher level of expertise than they actually do in other areas as well?
Arrogant know-it-all? Okay, it’s probably not an official psychological term but it’s what we call it.
I don’t think so. Arrogant know-it-alls are for the most part motivated by arrogance (and may not know anything about any fields altogether). What I’m talking about are people who are genuinely knowledgable in the areas that interest them and/or they work with, and are frequently “the smartest person in the room” in their areas of expertise, and thus have a tendency to transfer this attitude even in areas in which they are not experts. They may or may not be arrogant about it, but they automatically assume it.
In logic, it’s the fallacy of Appeal to False Authority.
Which is a particularly egregious variant of the fallacious Appeal to Authority.
Of course, both terms speak to believing an authority, as opposed to the purported authority’s false self-appointment.
The closest I can come up with is Illusory Superiority, but that’s more general (a manifestly ignorant moron can still suffer from the delusion of superiority).
I don’t know what you call it, but I know you haven’t truly experienced it until you’ve worked for doctors. 
I’ve heard emeritus syndrome, but I think there’s another phrase, too.
Rational wiki has a listing called Engineers and Woo, calling something similar the Salem Hypothesis.
Ah. Ultracrepidarianism.
Also, Nobel Disease. I think this is closer to being a common term. I’d never heard of ultracrepidarianism.
SDMB Charter Member
What?
Narcissistic Peronality Disorder?
Perceived Hyperintelligence Disorder (AKA PHD).
What I find funny is that one of our most common sayings is an example of what the OP is asking about: “If we can put a man on the moon, then surely we can also…”
…make a decent movie out of the Fantastic Four!
…brew a lower-calorie beer that doesn’t taste like seltzer water and broccoli farts!
…convince otherwise intelligent people that we did in fact put a man on the moon!
…have balls and strikes in baseball called by a computer in near-real time!
The modern term is “bloggers”.
Why would a Greek artist be speaking Latin?
I have a Ph.D. and one thing I know about is that I don’t know a damn thing. I may be unusual, but obtaining the doctorate made me very good at recognizing that I am ignorant of SOOooooo many things. There are a couple of things I know something about, but there’s a lot where I am totally clueless
Some Ph.D. types were always the smartest ones in their class…they are arrogant assholes. OThers, like me, recognize our limitations
But, I’ve had a couple of beers, so I don’t know what the hell I’m talking about.
The narrator (Pliny the Elder) was Roman and so writing in his own language. Presumably, if the story is not completely apocryphal, he translated from the original Greek into Latin for the sake of his audience (other Romans).
[your daily does of pedantic answers courtesy of me.]
The smartest people are generally those who feel least comfortable with their level of knowledge. The more you analyze things, the more you realize there are things you’re not taking into account. Those comfortable with their knowledge level generally aren’t trying hard enough to stump themselves.