Kevyn: You're perpetuating a horrible myth, Hob. Experts in a given scientific field seldom have expertise in multiple fields. The 'Mad Scientist' or 'Tinkering Hero' archetype is patently ridiculous. I'm a physicist, specializing in wormhole dynamics. I apply gravitic tunneling to the problems of managing receiverless teleportation. That does not make me a demolitions expert.
Hob: Wow. So you don't know 'splosives?
Kevyn: Actually, I do. But that's only because everybody needs a hobby.
"I'm a whizz at calculus, psychology,
plain geometry and anthropology
I'm the living end in entomology
and at bridge I excel
I know all about atomic energy
Horses, boats and cars and biochemistry
but when it comes to brain surgery then I can only do swell"
— Professor Ludwig Von Drake, Walt Disney's Wonderful World of Color
"I know more than you do — I'm Dr. Science!"
Here's another great example of Trek logic in action: if you were a science officer, you are automatically an expert on everything. Okay, I can see why she would be schooled in the science of made-up Trek physics when it comes to black holes. But she also knows everything about engineering, biology, nanotechnology, and anything else you might come up with. She even assisted the Doctor in brain surgery! How many times does Picard take over Engineering? How many times does Archer take the helm? How many times did Kirk get into a fist fight.... okay, bad example.
"Since it is considered extremely difficult to genuinely acquire an encyclopaedic knowledge, and even more to be proficient in several fields at the level of an expert (see expertise about research in this area), not to mention to achieve excellence or recognition in multiple fields, the word polymath, in both senses, may also be used, often ironically, with a potentially negative connotation as well. Under this connotation, by sacrificing depth for breadth, the polymath becomes a 'jack of all trades, master of none'."
"You dare mock me? When all of science is mine to command?"
— Baron Zemo, The Avengers #8
Abel: I'm surprised, Jyrras. I would have thought you would know a lot more about astronomy and astrology.
Jyrras: Eh. Meh. A lot of folks seem to think that if you are smart in one branch of science that you are an expert in all of them.
"According to the caption, he's both an astronomer and a nuclear physicist. Why can't scientists in fiction pick a damn field of study and just stick with it?"
"This is getting ridiculous! How much information did my other self — this timeline's Hank McCoy — have in his head?! It is as if the X-Men looked to him for everything from battle scenarios, tech-support and medical evaluations to studying the Legacy Virus!"
— Dark Beast, Uncanny X-Men #334
Zoe: This "Doctor" friend of yours. Is he a scientist?
Jamie: He is in a way I suppose, yes.
Zoe: What's his speciality?
Jamie: His what?
Zoe: Well, is he a physicist, biochemist, astronomer, biometrician?
Jamie: Yes, he is.
— Doctor Who, "The Wheel in Space"
Liz Shaw: What are you doctor of, by the way?
Intercom: One of them is calling himself a 'Doctor'.
Professor Yana: O-of medicine?
Intercom: He says 'of everything'.
— Doctor Who, "Utopia"
John: I have ten degrees, including all of yours... Except yours, Will.
Harry: That makes me feel a trifle lilliputian.
John: That's over the span of 170 years. I got my biology degree at Oxford in 1840, so I'm a little behind the times. The same in other areas— I can't keep up with the new stuff that comes along. No one can. Not even in their specialty.
Wonderella: What exactly are you a doctor of, anyway?