We are two students working in the same field under the supervision of the same professor within his chair and all of our publications are done together.

Hence I am curious: Is it generally possible in academia to submit a PhD thesis with two authors?

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    – eykanal
    Mar 22, 2017 at 21:23

5 Answers 5


A few answers have noted that PhD theses with two authors do exist, and that is interesting trivia.

However, I think it is useful to address your underlying issue. I.e., what is the best strategy to adopt when you are collaborating closely with another PhD student, you are working on a similar topic, and you have the same supervisor?

This situation arises for many PhD students (I can think of a few), yet they still work out a way to write their own thesis.

If you are publishing joint papers, then you may want to think about ways that you and the other student can be the lead author on different papers. You probably also want to formalise the description of who made what contributions to each paper. I know at my institution, papers that form part of a PhD need to have a statement signed by all co-authors listing the contribution of each author.

You want to think about how your thesis can be distinct. You should work with your supervisor to carve out your unique focus.


It is definitely possible in the sense of "It has been done." However, the only example I know of is this thesis from linguistics: http://dare.uva.nl/search?arno.record.id=123669 (Groenendijk & Stokhof 1984)

Whether it is possible in the sense of "You could do it." will depend on your university's regulations concerning these matters, as well as your advisors and committee's preferences. They are the people you should talk to about this.

  • Yes, indeed. I know another very high-profile (and deserved!) case which I won't name here, and was accepted at very high-profile level. But it is strongly inadvisable in general, as the risk is very high. Mar 21, 2017 at 10:51
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    Just out of curiosity, is there a reason not to name that thesis, given that it's published anyway?
    – Andreas
    Mar 21, 2017 at 12:36
  • 5
    Calling @CaptainEmacs ... At least 4 people want to know more. ;-)
    – Mad Jack
    Mar 21, 2017 at 14:53
  • I am not sure how much of the story is public knowledge (probably it is, but I do not want to take chances). I can, however assure you, that the thesis is worth it. Mar 21, 2017 at 15:48
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    Ok, but couldn't you just give the reference without the story?
    – Andreas
    Mar 21, 2017 at 15:52

No. The PhD thesis consists of your personal contribution to the field and is a demonstration of your expertise.

This presented a problem for a pair of fellow PhD students while I was working on my degree (in the sciences, in the United States). They published numerous impactful papers a co-first authors, but thesis committee members had many objections for the student had the misfortune of presenting second. They had to clearly delineate their personal contributions in the thesis itself, where each had to have enough to individually merit the degree. This was a complete headache for both of them and ended up being a significant amount of extra work.

This merits a discussion between you, your advisor, and your colleague before you get any further in the proposal/thesis writing process.

Edit: As a few have mentioned, it seems like there are some instances where they are accepted - but the overall trend is that they are very uncommon. Do to the many reasons listed in the multiple responses, they are not recommended in general even if allowed by your university. In any case, you both would still need to prove each of your personal contributions are deserving of a PhD.

  • 1
    Sorry, but this is wrong in general. The regulations at my university explicitly allow group dissertations if the contributions can be separated.
    – Dirk
    Mar 22, 2017 at 16:43

It happened to me to a lesser extent: a small part of my PhD research was in collaboration with another PhD student in another continent. When we were about to write our thesis (more less at same time) our adviser had to come to a mutual agreement on what part would be in my thesis and what part to my colleague's thesis. Even if it was not against the rules to include the same work, it definitely wasn't advisable to do so to avoid any potential awkward situation in the future.

Even if the adviser agrees, and even if it's technically not against university rules it could potentially raise many red flags in the future for someone that catches the situation (and I think it will be very easy for someone to spot it). I would strongly advise not to.

  • With a huge overlap of publication, the situation you are describing could actually be alleviated by a double thesis. Anyway, the question did not ask whether doing this is a good idea (in either version).
    – Wrzlprmft
    Mar 21, 2017 at 16:49
  • @Wrzlprmft It asked if it's possible. I said that, according to my experience, it's not possible, but not necessarily according to strict rules.
    – PsySp
    Mar 21, 2017 at 16:52

Yes, it is technically possible if your advisor and university agree, which is a big if. In addition to the example from linguistics mentioned in the previous answer, there is the Krohn-Rhodes theorem, which appeared in the identical dissertations of Krohn and Rhodes. See, for example, page viii of "Applications of Automata Theory and Algebra" by John Rhodes.

However, you shouldn't even think about trying this yourself. It's vanishingly rare (I'd guess somewhere between one in ten thousand and one in a hundred thousand dissertations), and unless your thesis is absolutely amazing, this will immediately become by far its most attention-getting aspect. That's really not what you want people to focus on while you are trying to establish your reputation.

  • I don't know, it depends what you want your PhD for. It would make you memorable, and a lot of companies might not care that much. Mar 22, 2017 at 0:14
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    Could you make a specific link to the answer instead of saying "previous example"? The order of answers tends to shift.
    – Weckar E.
    Mar 22, 2017 at 8:49

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