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It is possible to obtain two PhD degrees (various fields) on the basis of one interdisciplinary PhD dissertation? Is this something feasible (in Europe)?

Or maybe there must be two different 'physical' doctoral dissertations?

Nate Eldredge
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Aurelio
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    Usually not, because it's forbidden to defend the same thesis twice. – NoDataDumpNoContribution Mar 10 '18 at 13:18
  • Related: https://academia.stackexchange.com/questions/17232/is-doing-two-phds-a-good-path/17245 – Mark Meckes Mar 10 '18 at 13:32
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    Why would you want to? It seems like a waste of energy to me. A research degree is a paper saying that a department at a university judges you able to do independent research on a scientific level. Why would you want two of those? – mathreadler Mar 10 '18 at 15:25
  • If you love to research then you should research instead of getting back into the situation in which you have heckloads of obligations other than research to do. If you don't love research but got the degree to get some job in industry which requires the degree then you should go for that job. – mathreadler Mar 10 '18 at 15:33
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    @mathreadler A PhD in a particular field is often taken to be a strong qualification of one's expertise in that field. It's not strictly necessary to have multiple PhD's to be have cross-disciplinary credibility, though it certainly could be helpful. – Nat Mar 10 '18 at 19:15
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    @Nat I don't think so. Most people would be puzzled why you'd even think of doing it. I think many people would be curious to ask "So why did you go for a second PhD? Could you not find any post doc spot or assistant professor spot, or job in industry..?". – mathreadler Mar 10 '18 at 23:19
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    I have seen this happen, with multiple cases of the same student earning PhDs from different departments (somewhat related topic areas) at the same top university. One department required a private defense and the other, a public defense, so I think there were two defenses. For privacy reasons, I can't name names. – WBT Mar 11 '18 at 18:23
  • I believe it is possible, as @WBT has mentioned. I think I have heard of such a case. I even understand the logical reasons behind it, and how it could positively benefit one's CV. But I do not think this is a good move you intend to stay in the academia because most people will see it as borderline unethical at best. – Scientist Mar 31 '18 at 04:55
  • I'm intrigued by this question! Suppose someone researches two fields during their PhD and publishes manuscripts for both, then can they take manuscripts for one field and write a dissertation, and take the manuscripts from the other field and write a second dissertation? The dissertations are based on distinct manuscripts, hence, the objections below do not apply. Of course, producing enough research to fill two dissertations is probably beyond the vast majority! – user2768 Nov 28 '18 at 09:54

3 Answers3

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No, at least the regulations that I am aware of require that the dissertation be a novel contribution to the respective field and that it has not been submitted before.

If you write a dissertation at the crossroads of different fields, you have to decide for a field in which you want to formally graduate and obtain a degree. It may be advisable to look for supervisors from different fields or with an interdisciplinary background.

henning
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It's hard to imagine any legitimate university allowing a thesis that has already been submitted for some other degree, whether at that university or somewhere else.* If you lied and claimed it was a new thesis, your degree would be revoked if they ever found out. Furthermore, there are more requirements to earning a PhD than just presenting a dissertation. You're not going to be able to register as a student and submit a pre-prepared dissertation the next day.

And, anyway, what's the point? A PhD is generally treated as a level of achievement, rather than a quantity of achievement. Getting two PhDs is like getting two driving licenses. That doesn't show you're twice as good a driver – it's just saying "I can drive" twice. Why would you want to prove twice that you're at the same level, instead of using all that time to advance beyond the level of being a grad student?

Having two PhDs is so unusual that everybody is going to ask you about both of them. How impressed do you think they'll be when you admit that this second PhD you were bragging about was just the resubmission of the same dissertation to another university?

 * And note that la femme cosmique's answer is a case of the same thesis being simultaneously submitted to two universities as part of a joint programme that both universities agree to when the student enrolled.

David Richerby
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    Getting two PhDs is like having two driving licenses. I have to remember that one. – henning Mar 10 '18 at 13:06
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    Some universities allow this. I have a friend who did 2 years of his PhD in France and 1 year in China. He now holds, at completion, a PhD from the French institution and a PhD from the Chinese one, from one thesis (although separately in English and Chinese). But it's still the same field. Semi-related. OP could find a 'co-tutuelle'-ish arrangement between two institutions/groups in different fields in which this is theoretically possible, but that would be a pre-established relationship rather than something to do during the PhD. – la femme cosmique Mar 10 '18 at 13:10
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    @lafemmecosmique That's interesting to know. I think it would make a good answer. – David Richerby Mar 10 '18 at 13:18
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    I have two driving licenses -- one for the left and one for the right. :P – Thomas Mar 10 '18 at 23:26
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    @DavidRicherby ok, I added it as a "super specific but theoretically possible" answer. – la femme cosmique Mar 11 '18 at 12:08
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    Well, I finished one PhD in chemistry, but thinking to take one in humanities/social science, I am stupid for dooing it? – SSimon Mar 11 '18 at 14:46
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    "Getting two PhDs is like getting two driving licenses." - which can be very reasonable thing when wanting to drive in two different "contexts" (here: traffic legislations). The driving licenses indeed seem to be a pretty good analogy to why it can theoretically make sense to get two doctoral degrees in different fields. – O. R. Mapper Mar 11 '18 at 14:49
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    @DavidRicherby You can read something about the double degrees achievable through agreements between universities in the answers to this question. – Massimo Ortolano Mar 11 '18 at 15:13
  • @O.R.Mapper Of course, the analogy isn't perfect. However, most countries accept other countries' licenses as evidence of competence to drive on short-term visits. If you want to drive long-term in a country, you typically need to get a license in that country but my understanding is that this is basically because it's impossible to impose penalty points on a foreign license. As for multiple PhDs, the asker of this question wants to use the same thesis to prove that they're good at two different subjects. But you don't need two PhDs to do that: you just need to say "Hey, look at my PhD in... – David Richerby Mar 11 '18 at 15:46
  • ... widget-theoretic aspects of gizmo studies. That proves that I'm good at widget theory as well as gizmos." They don't need to say "I have a PhD in widget theory and a PhD in gizmo studies" to prove that. – David Richerby Mar 11 '18 at 15:47
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    @SSimon Well, to stretch the analogy a little, that sounds much more like getting, say, a car license and a truck license since you're proposing PhDs in two completely different subjects. The asker is proposing to use the same thesis to get PhDs in two different fields whose intersection includes that thesis. – David Richerby Mar 11 '18 at 15:49
  • @DavidRicherby: "most countries accept other countries' licenses as evidence of competence to drive on short-term visits" - yes, that's why I wrote "theoretically". Seeing on [travel.se] and other travel-related message boards how drivers cause dangerous situations simply because they are allowed to drive somewhere with a foreign license, but without any requirement of familiarizing with the local laws of the road (that can differ in basic things such as default right of way at junctions compared to their home country), it arguably isn't very reasonable other than for facilitating the ... – O. R. Mapper Mar 11 '18 at 16:17
  • ... whole process. Local rules and conventions differ. And the same can be said about different research fields. Note that my comment referred exclusively to the cited statement about two doctoral degrees being pointless, not to the OP's particular case of wanting to use the very same research work to obtain two degrees. – O. R. Mapper Mar 11 '18 at 16:18
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It is possible to do this, but usually the arrangements are pre-designated before you do the PhD. My answer is going to be very specific here; I have a friend who did this, and I know it's "a thing" at least in France. But as I said, the scope of the answer is therefore limited to a PhD done jointly between a French lab and one somewhere else.

A friend of mine has done a "co-tutelle internationale de these" which means that he spent 1 year of his PhD in his home country (China) and 2 years in a lab in France (paid by the Chinese government). At the end he wrote his thesis in Chinese and again in English (with a French abstract), defended in China, and he has two PhDs; one from the home institution and one from the French one. These agreements are somewhat common, at least in France, although I cannot really speak for other countries. However, that does mean that it is theoretically possible. As far as I'm aware, besides the language, the theses he submitted were the same.

It is not difficult to imagine a situation in which one of the labs is a different discipline to another (e.g. something like engineering vs. astrophysics) and so you could end up with 2 PhDs in such an arrangement. However these things are pre-arranged before the start of the PhD, and to form a new one would probably be a lot of administrative work.

However, it's possible, at least here.

Some stuff about it is written here:

https://ressources.campusfrance.org/catalogues_recherche/diplomes/fr/cotutelle_fr.pdf

Especially the paragraph that I'll poorly translate:

Which degree do we obtain?

Each cotutelle thesis is held within the framework of a convention linking two institutions of which one is necessarily French. The procedures and rules are those of the French doctorate and those of the doctorate in the partner country. The two universities recognize the validity of the cotutelle set up and that of the degree supported (grade of Doctor for French university and equivalent diploma for foreign university).

Concerning the issue of the diploma, there are 2 possibilities:

• The student receives a Doctor's degree conferred jointly by both institutions. The diploma is mentioned under his two appellations (for example: PhD in French literature and PhD in French literature).

• The student receives two doctoral degrees from each institution. Each diploma then bears the mention of the diploma specific to each institution, mentions the fact that the thesis was made in co-supervision and specifies the name of the partner institution.

In both cases, the thesis is defended in only one of the two institutions associated with the cotutelle, by decision of the two research directors.

But this is a highly-specific answer which is France-centric. Is that possible elsewhere? Probably. But I don't know enough about it to answer.

la femme cosmique
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  • Yes, it's possible elsewhere, see also this answer of mine. I know of different cases, e.g. Italy/France (a student of mine who graduated last year), Italy/Germany and Italy/Finland. – Massimo Ortolano Mar 11 '18 at 15:18
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    I wonder how much these dual degree programs are really just the result of (or vestiges of, in the case of a post-Bologna Europe) bureaucratic headaches that people have to have their degrees recognized in different countries. I'm not aware of any of these programs being within the same country (unless one is a professional degree, e.g., MD/PhD at Emory / Georgia Tech) – user0721090601 Mar 11 '18 at 16:04
  • @guifa knowing French administration, this would not surprise me in the least ;) – la femme cosmique Mar 11 '18 at 16:31