Why is it disadvantageous in graduate admissions to have a higher degree?

Question

JeffE's answer here indicates that holders of a master’s degree are held to higher standards when it comes to graduate admissions. The stated requirements for some graduate programs (example from UC Berkeley) also outright exclude applicants with doctoral degrees. These seem to be saying that holding a higher degree prior to application is a disadvantage (a fatal one in the case of a PhD). This also applies to private universities: Stanford apparently has the same restriction (at least in computer science); same goes for MIT.

I don't understand why:

• If there are two applicants, Alice and Bob, who have achieved largely similar things, it seems logical that both should have a roughly equal chance of being admitted. However, based on JeffE's answer, if Alice has a Masters degree while Bob does not, it's Bob that gets admitted instead of Alice. JeffE's answer even indicates that if Alice has achieved slightly more than Bob, it's still Bob that gets admitted.

• If graduate admissions is looking for students that are capable of succeeding in its program, then Alice should be more likely to succeed than Bob since she's already had some experience of graduate study. This should be even more the case if Alice already has a PhD – if she can do it once, she should be able to do it again.

JeffE's answer indicates that since Alice has had more opportunities than Bob, she should also be held to higher standard. However it should also be true that Alice has already achieved what Bob has yet to and in fact might not be able to achieve. Further, JeffE's answer seems to be saying that Alice should do the academic equivalent of financial engineering and pass her graduate-level courses & thesis without getting a master’s degree even if she qualifies for it, which sounds silly.

As for applicants with PhD degrees, my first guess would be that this is because multiple PhDs is not a good idea, and the university is acting in the applicant's best interests. However if this is the case, then this is effectively telling the applicant "I know what you want better than you do", which also sounds silly. UC Berkeley's requirements also seem to be saying that if someone with a CV worthy of a tenured position were to apply for a PhD student position, the university will say "no" even though it's clearly better in their best interests (in terms of research output) to say "yes".

Presumably I'm misunderstanding something because if this behavior were irrational, it would already have been changed. What am I missing?

EDIT: I wonder if things are different in programs where the student is involved in research directly without spending time on coursework?

Answer 1

What we are looking for, or at least I'm looking for, when talking about graduate admissions is your potential as a researcher.

I'll touch on the PhD portion, which I think is actually more obvious, and then move onto the Masters.

PhD: As Nate Eldredge notes, one of the concepts behind a PhD is that you should have learned how to engage with a field, interact with the literature, learned new methods, etc. And you should have learned how to do it beyond what's taught in classes. Applying for a new degree program, unless it is in a vastly different field, suggests that you have tried to move into a different area and have failed enough that you think you need to go back for coursework and supervised learning. That's not a good sign.

Masters Degrees: The thing about a Masters is that, in some ways, you've already taken a "swing at the bat" - which means that you've had the chance to show your potential - so you need to have done so.

If there are two applicants, Alice and Bob, who have achieved largely similar things, it seems logical that both should have a roughly equal chance of being admitted. However, based on JeffE's answer, if Alice has a Masters degree while Bob does not, it's Bob that gets admitted instead of Alice. JeffE's answer even indicates that if Alice has achieved slightly more than Bob, it's still Bob that gets admitted.

In this case, they actually haven't achieved similar things. If Bob has gotten the same output despite not having Masters level coursework, access to faculty at the graduate level, etc. then they haven't achieved the same thing.

If graduate admissions is looking for students that are capable of succeeding in its program, then Alice should be more likely to succeed than Bob since she's already had some experience of graduate study. This should be even more the case if Alice already has a PhD - if she can do it once, she should be able to do it again.

"Getting through my degree program" is not actually what I'm looking for. For some reason, if Alice is reapplying to a PhD program, she has gotten through with all the tools she needs...and then wants to go back for more tools. That's not a good leading indicator of her potential as an independent researcher in the future.

However if this is the case, then this is effectively telling the applicant "I know what you want better than you do", which also sounds silly.

They probably do. If nothing else, UC Berkeley is working with a much larger experiential data set.

UC Berkeley's requirements also seem to be saying that if someone with a CV worthy of a tenured position were to apply for a PhD student position, the university will say "no" even though it's clearly better in their best interests (in terms of research output) to say "yes".

An extremely unlikely edge case that might prompt an exemption to their policy, but policy is not written for once-a-generation savants.

Answer 2

Berkeley offers the following rationale for their policy:

The Graduate Council views academic degrees as evidence of broad research training, not as vocational training certificates; therefore, applicants who already have academic graduate degrees should be able to take up new subject matter on a serious level without undertaking a graduate program, unless the fields are completely dissimilar.

Although this is rather vague, it does suggest that they believe that when one already has a PhD, it is pointless to enter another graduate program in a similar field, as one has already demonstrated "broad research training" and shouldn't need more. And since PhD program spaces are a limited resource, and involve a considerable investment of faculty time and university resources, they don't want to spend it in ways that they consider pointless.

That's my interpretation, anyway.

Answer 3

If there are two applicants, Alice and Bob, who have achieved largely similar things, it seems logical that both should have a roughly equal chance of being admitted.

Not at all. PhD admission is primarily based on potential for future success as an independent researcher. Between two people with identical research portfolios, it is natural to judge the person who built their portfolio faster and with fewer opportunities to have stronger potential for future success.

If graduate admissions is looking for students that are capable of succeeding in its program, then Alice should be more likely to succeed than Bob since she's already had some experience of graduate study.

You've moved the goalposts. If Alice produces more concrete evidence of research potential than Bob as a result of her graduate study, then she meets the higher standard expected of applicants with graduate-school experience! On the other hand, if Alice does not produce more concrete evidence of research potential than Bob, despite her experience of graduate study, then Bob is a more attractive candidate.

Merely having been a graduate student is not by itself evidence of research potential; research rarely resembles coursework.

Answer 4

Whether it is made explicit or not, I would imagine that most graduate programs try to evaluate candidates on the basis of future potential. Probably most programs should be more clear about this.

So, for example, if one has been allowed to take qualifying exams endlessly, for 20 years or so, and eventually passes all of them... what does it mean?

It's like age or weight classes in various sports. The possible fact that a 30-year-old can bat 1000 in T-ball aimed at 5-year olds does not earn a spot on a major-league team in the U.S.

Although there's very little age-ism practiced in the U.S. in PhD admissions in mathematics... the point is not "maxing out on prelim exams", or anything similar. It is infinitely more about people on an upward trajectory...

Answer 5

If by "succeeding in its program," you only mean finishing a PhD, then your premise that a graduate program is looking for students capable of succeeding in its program is quite flawed.

The impression I got from my graduate program is that they consider outcomes like mine failures, and I have a tenured position in a department with a PhD program, albeit a low-ranked one, and publish a paper or two a year.

If they had a choice between Student A, whom they thought was 100% likely to end up in a position like mine, or Student B, whom they thought was a 20% chance to end up in a top-30 research department with an NSF grant and an 80% chance to drop out after 2 years, I'm pretty sure they'd take Student B. In fact, if there was Student C, whom they thought was a 2% chance of eventually winning the Fields Medal and a 98% chance of dropping out in the middle of their fifth semester, dropping the ball on their teaching duties, I'm not sure they wouldn't prefer Student C to both.

If you have already had graduate studies and did well but not brilliantly, you've proven that you won't be a disaster, but you've also shown you are less likely to be wildly successful.

Answer 6

PhD students do useful research work. Supervisors will want a PhD student who successfully completes a project. A candidate who already has a PhD may be more likely to quit prematurely. I've seen it happen.

When I did my PhD, a new colleague PhD student joined. He already had a PhD from a developing country, from a university that is perhaps not very well known outside his home country. He considered that a PhD from a more established university in a more developed country would be more valuable.

Fast-forward two years, he suddenly left when to take up a postdoc position in yet another developed country. His supervisor was not happy, and I expect will think twice before accepting again a PhD student who already has a PhD.

Answer 7

In addition to the other excellent answers (from people who have infinitely more experience with the process than I), consider: It seems to be the case that for successful researchers, there is unique academic credit/prestige assigned to the PhD awarding department and advisor. Examples: (1) Richard Lipton's blog. (2) Joel David Hamkins' blog. If a person has multiple PhD's, then who gets that credit? At best this credit would seem to get split and diluted. At worst, one or the other is at risk of being forgotten entirely.