"they would ... end up with lots of well-trained postdocs who cannot find jobs for which they have been educated" Well, isn't that EXACTLY what happens?

@Szabolcs It is true in the sense that there are a lot of people who do a postdoc or two and then switch to a non-academic job. In the contexts of OPs question that means there are too many postdocs (and not too few) relative to the number of professor positions available to them later on.

@Szabolcs It would be a weird system where every postdoc actually gets a faculty position. That means that even those who turn out to be unqualified get a job. You would expect that supply is higher than demand so that employers have a choice. (Similarly, you wouldn't expect every student with a 2.0 GPA to get a job that requires a college education.)

@WolfgangBangerth, you would expect some surplus, also because post-doc themselves can change their minds on what they want to do. But take into account that these people were heavily selected for when they got into their PhD (at least at a good place). They were then heavily selected for when finding their first post-doc. At this point people have invested over 10 years specializing in a specific field in academia. It would be nice if at this point they can find a job that actually uses these skills.

@Kvothe Selection happens at every level. Second-level managers are also already highly selected, yet there are many more of them than CEOs. Only a few of them become CEO themselves, even though they are all already highly selected and qualified.

@quarague I would rather argue that there are too few stable, long-term employment options for post-docs. Increasing the number of post-doc positions while decreasing the number of PhD positions would remedy both problems at once: there would be fewer post-docs to begin with, and there would be more positions for them.

@jhin But why would we need more postdoc positions? And what would be the societal benefit for reducing the number of training spots for graduate students? Companies very much like to hire them, at very good salaries. States benefit if their universities educate them.

@WolfgangBangerth Point partially well taken. ;-) I was mostly coming from an academic perspective, from which I believed (and still have not really been convinced otherwise) it would be beneficial to have a lower phd:postdoc ratio. But you're probably right; I was discounting the value of PhDs for the (non-academic) economy. Nevertheless, one could (and people do) argue that the current system is quite harmful to early-career researchers due to high levels of instability and insecurity, and remedying this problem might be in the interest of society as well.

Industry will always prefer a more trained candidate if they can get it at the same price, the societal effect is extending education on almost indefinitely. The education system wants to gobble up more money so it's invested in rationalizing why people need 10+years of post highschool education but this doesn't translate into real industry need.

@FourierFlux In which ways does the education system actually "gobble up more money" by hiring PhDs instead of postdocs? AFAIK, funding is usually based on the (supposed) merits of a research project, and not based on how many PhDs the project will train?

@WolfgangBangerth I added a few sources to the question concerning the potential societal benefits of fixing the "postdoc job insecurity problem".

My comment is more related to the expansion of the university system and the dramatic increase in graduates at every level. The number of open PostDoc positions reflect the reality of the academic job market while the quantity of PhD which are graduating reflects a bubble in higher education. I would argue a PhD should only exist for the academic job market but it's been twisted into an "industry degree" because of the above.

@jhin I think it is wrong to focus on the ratio of phd vs postdoc positions. A better question to ask is whether there are too many or too little of either.

@WolfgangBangerth Well, but that would require changing budgets, right? The question I'm asking is: why does "the research community", given the budget it gets by the government and industry, decide to distribute its money the way it does on PhDs and postdocs?

@jhin - a long-term post-doc is not a stable career...

@JonCuster Isn't "long-term" kind of the definition of stable...? E.g., a colleague of mine got an unlimited contract for a post-doc researcher position (no supervision duties, no administrative duties, just an unlimited contract for a researcher with a PhD) right after his PhD.

@WolfgangBangerth What are you trying to say by that? That you believe that the system is fair and as it should be? That you believe that those who didn't get a faculty job were just not good enough and didn't deserve one? Do you have any idea at all about what percentage of postdocs—presumably all of whom were aiming for a faculty job—actually end up getting one? Even postdocs from "good" institutions (which makes a difference for their chances even if it shouldn't)? Someone in your position should really know better.

@jhin - long-term soft-money (year-to-year contracts) are not stable, in my opinion. Maybe you enjoy wondering if there is funding for you next year, year after year, but most folks won't. There is no commitment to a post-doc position. A long-term post-doc-like position is called a professor or technical staff member.

@jhin Moving money from graduate students to postdocs also requires changing budgets. It's not like a university gets a single bucket of money and can then decide what it wants to do with it. Universities get dozens or hundreds of different buckets, all associated with restrictions on how and on whom they can be spent, from state governments. Then universities get thousands more buckets in the form of federal grants (talking about the US at least), each of which also have restrictions whether money can be spent on graduate student, postdoc, or faculty salaries.

@Szabolcs I went through the system too, with all of its uncertainty. I didn't enjoy it. But I don't think that it is fundamentally unfair. I think that by and large, the best postdoc candidates get faculty positions, substantial issues with diversity notwithstanding. I see no reason to believe that every postdoc deserves a faculty position or would even be qualified for a faculty position. I've seen many applications that simply weren't competitive.

@WolfgangBangerth Once again, are you aware of what fraction of postdocs actually get a faculty job? Does your department collect statistics, or ever follow up with people who left? If yes, please take a look. If not, get them to do it, if you care at all about the issue. Based on your comments here, it should be an eye opener for you.

@JonCuster I completely agree regarding year-to-year contracts; I was not talking about those (as indicated by the example of my colleague). Is a postdoc position per definition fixed-term? I was somehow assuming any staff research position one takes after a PhD could be called a postdoc position, whether fixed-term or unlimited.

@jhin - at my institution, a postdoc is renewed yearly for up to a maximum term. It is explicitly limited in duration. Anything over 3 years and I would be justifying to HR, no extensions over 6 years allowed by policy (and, really, HR won't go past 3 anyway). A staff position is not a post-doc, even when I've hired directly from a PhD.

@Szabolcs You accuse me of not caring, but that's just not true. I've mentored six postdocs, all of whom I greatly care about. Of those, two are in long-term positions and three others have long-term stable jobs for which they are outstandingly well qualified. The sixth is on the right track. I just don't believe that we should only take in as many postdocs as there are faculty positions, primarily because I don't see taking any other job than a faculty job as a failure. There are many other rewarding and satisfying careers you can get into from a postdoc position.

"long-term positions" -> "long-term faculty positions".