Just pulling a random site (first hit on a search) https://www.findaphd.com/phds/browsebysubject.aspx
It appears you can get a phd in dance, event management, or dozens of fields that aren't curing cancer, or AI.
I'm reminded of the Olympic break dancer who did the "kangaroo" move. She has a PHD:
https://en.wikipedia.org/wiki/Rachael_Gunn
thesis: "Her PhD thesis, titled Deterritorializing Gender in Sydney's Breakdancing Scene: A B-girl's Experience of B-boying" (from Wikipedia)
Now I'm sure it was worthwhile, but I'm struggling to see it as a presumptive positive move to humanity for her work.
And there's lots just like it.
I'd even go so far as to assume that it's the extreme minority of phds that actually make a difference "for humanity" and not simply a good career move for the degree holder.
More important to me is whether it was written because someone really cared about the topic, or wrote 100s of pages of nothing to have a title.
But I also want to comment on your idea that researching AI is superior to researching dancing because it is more beneficial for humanity. I am myself in AI adjacent research, but I still disagree. Dancing is a deeply human thing, and we should care about it. And I believe that many people (especially outside of this bubble) will think that many parts of currently hyped AI research has very questionable "benefit for humanity", such as AI image generators.
I am not dismissing the value of dance or culture or social science or even event management (or farming or any of the dozens and dozens of things people can get Ph.D's in).
And I note that in my post above.
I am seriously not being sarcastic by saying it's worthwhile. Probably to her. Maybe her department. Maybe even to break dancing (well, maybe not break dancing).
But the presumption that someone getting a Ph.D has somehow "uplifted us all" as a default seems highly improbable to me.
It no doubt uplifts a number of the degree holders, if statistics bear out.
But that's like saying "If Elon Musk becomes rich, we all become rich" and I don't think that's true. Not even in some "trickle down" economics kinda way.
If Elon gets a Ph.D we have all to assume some intrinsic benefit to humanity?
Uhm, I don't think so.
I chose arbitrary fields that I suspected most readers of HN wouldn't be in, be familiar with, or necessarily esteem just to make the case more obvious. For example, a Ph.D in dance.
There are lots and lots of PhDs in all kinds of things. You can get a Phd in videogames, food hygiene, librarianship, gender studies, ancient greek, theology.
I am sure they are (mostly) worthwhile, and I'm not knocking any of them.
I don't see how they would, by default, be seen to benefit humanity. Some small number might. A very small number. Possibly an extremely small number.
According to one random website there are over 70,000 new PhDs every year.
That's a lot of assumed benefit to humanity. Or.. is it?
I provide this example of a dance PhD thesis topic:
"Deterritorializing Gender in Sydney's Breakdancing Scene: A B-girl's Experience of B-boying" by Rachel Gunn of "kangaroo" breakdance olympic fame.
Anyone can read a book and write an essay. Even AI can write reasonable essays these days. Is AI advancing the pursuit of knowledge?
And you are missing my point about the wide range of fields to which these novice experts are coming from.
Rachael Gunn is an expert in the field of (break)dance, if I extend your position, and her essay is an expert testimony broadening the field of knowledge?
I think it's entirely possible for PhD (or Masters or anyone) to extend debunked theories, to extend or invent nonsensical positions yet to be debunked, to do research of no value, or merely for value to the student and their advisor as a way to increase citations, career advancement, and so on.
I would argue that this is a more reasonable default assumption. In fact, I think the university system favors this likelihood. Students aren't, to my knowledge, asked to examine the worlds problems and take a stab at them.
They are lead into very specific tracks, possibly by their advisor, possibly by the department, possibly by funding or current trends in the field, to do work around a particular area which may go nowhere close to helping all of humanity.
And a "thesis" is just a a really long essay. It has no special quality or instrinsic value, in my humble opinion.
Does fraud happen? Of course. Do people submit more papers on hot topics because they think they are more likely to be approved? Of course. Are some people plagiarizing or misrepresenting the impact of their work? Of course. But the point is to reduce this, and the specific goal organizationally is to reduce these because they harm the reputation and purity of the idea.
I feel like your concern is similar to someone going “firefighting is not actually intrinsically beneficial for humanity”. When someone tells me they’re a firefighter I generally think that they’re doing something valuable. You can argue, well some of them use it as an excuse to get inside a house so they can loot it. Or others are private firefighters for oil companies, and not the “good” community firefighters that save houses. Maybe some of them are doing it for the money and not because they actually particularly care for saving people. But I would counter that the concept is sound and that obvious abuse is, in theory, supposed to be punished.