Few days back while attending a thesis defense, one Professor was asking the defender why does he think, he deserves the degree. I was wondering since then, is there really any general answer for that? or the answer should be given describing my own work and then emphasis them how it is important for research field?

I asked the question here to know your opinion about it and to list down what could be the possible answers to this question.

  • 138
    Wow, what an awful question to ask during a thesis defense. Commented Dec 17, 2014 at 9:45
  • 8
    @TobiasKildetoft I agree, it may appear awful, but it may just be that the professor wanted to see whether the student can describe the novelty aspects of the thesis' results.
    – silvado
    Commented Dec 17, 2014 at 10:07
  • 55
    "I fulfilled all of the requirements." Commented Dec 17, 2014 at 16:42
  • 7
    "I don't know, you tell me!" Commented Dec 17, 2014 at 21:26
  • 5
    Eight years or more, working full time, pushing the limits of human knowledge, do you need to validate it any more?
    – sam_smith
    Commented Dec 17, 2014 at 22:06

8 Answers 8


For a Ph.D., my favorite explanation is this cartoon by Matt Might.

In short: a Ph.D. is a measurable contribution to a sum of human knowledge.

To be able to answer this question, all you need is an idea of how to describe what you have discovered, and how it fits into the context of work by others that has come before. This is often not easy to answer, but an important thing to think about as one is writing one's thesis in any case.

  • 2
    Had the same thought. The size of the contribution demonstrated in the cartoon is also key to answer the deservingness question: the contribution needs to be measurable but it need not necessarily be large in any absolute sense.
    – Thomas
    Commented Dec 17, 2014 at 10:08
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    The only thing I disagree with on that cartoon is depicting the human knowledge as a solid circle. As my friend once put it, it rather looks like Serpinski's gasket: there are very long lines in many directions but it is still nowhere dense and a small sidestep in an "orthogonal direction" can bring you to terra incognita right from where you stand at any moment.
    – fedja
    Commented Dec 17, 2014 at 13:30
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    @fedja Another interesting view on this a fellow student mentioned is that the sum of human knowledge is not an ever growing connected region, but a hollow disc in which we are constantly scaffolding outwards while forgetting inwards. This is evidenced by how often the idea "All good ideas have already been conceived" is itself reconceived :D
    – Tim
    Commented Dec 17, 2014 at 17:22
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    @Tim Indeed, that is true on high levels. Fortunately, one good side effect of human mortality is that we cannot make the new generation reach the outer annulus without maintaining at least some pathways to there from ground zero :-)
    – fedja
    Commented Dec 17, 2014 at 17:35

Usually the answer to this is formulated in the rules of the institution. In Germany we call this the "Bachelor-/Masterprüfungsordnung" (for BSc and Msc) or "Promotionsordnung" (for a PhD).

The one from my institution contains something like

Die Promotion dient dem Nachweis der Befähigung zu vertiefter selbständiger wissenschaftlicher Arbeit.

which translates roughly to

The PhD degree certifies the ability for in-depth and independent scientific work.

It also says that one needs a written work (called dissertation) and an oral exam. For the dissertation there is

Die Dissertation muss die Befähigung der Verfasserin oder des Verfassers zu vertiefter und selbständiger wissenschaftlicher Arbeit nachweisen und einen Beitrag zum Fortschritt der Wissenschaft auf [insert some field] darstellen.

which is roughly

The dissertation has to certify the ability of the writer to do in-depth and independent scientific work, and to contribute to the advancement of science in [insert some field].

There are also some regulations for the oral exam but actually there is not a specific term what constitutes a passed or failed oral exam.

  • 16
    "The PhD degree certifies the ability for in-depth and independent scientific work." Indeed. However, if I were asked to say "I am able of in-depth and independent scientific work" in public, I would either blush from the top of my head to the toes, or collapse in uncontrollable laughter. Such phrases are intended for using on other people and other people only.
    – fedja
    Commented Dec 17, 2014 at 13:40
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    Yeah sure, but I thought it would be good to have fact here and the OP asked for a "general answer".
    – Dirk
    Commented Dec 17, 2014 at 18:17
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    If @Bee decides to "accept" an answer, this one ought to be it. Spot on: the fitness of the research for the award of degree is institutionally defined, and does vary between universities. This is the thinking person's version of Austin Henley's comment to OP: "I fulfilled all of the requirements." Right - what requirements were those again?
    – Dɑvïd
    Commented Dec 19, 2014 at 23:16
  • These two things are the essentials (1. independent work 2. independent report). To formulate it to fit to a conversation/defense I would say "My thesis shows that I can do scientific work on my own. I have done the research and I written the report independently with the guidance of my Professor (and collaborators)". The last part is the expected acknowledgement which is also essential part of scientific behavior and reporting (be polite and share credit).
    – Juha
    Commented Dec 21, 2014 at 6:40
  • Yap I'm pretty sure that is what I remember too : ability to conduct in-depth independent scientific work, nothing about advancing human blahoo or blahaa. Commented Mar 23, 2018 at 22:38

When I arrived to this question, there was (and probably still is) a highly upvoted comment:

"I fulfilled all of the requirements." — Austin Henley

I think that it's very easy for a new PhD or candidate to have serious doubts about the quality of their work, and to suffer a bit of the impostor syndrome. After all, they've spent numerous years seeing just how much knowledge is out there, and realizing that despite their new expertise, in the big scheme of things, it's actually a pretty small piece.

I've just completed my PhD, and one of the things that my advisor mentioned to me was very helpful, especially when I was feeling a bit of what I've described above. At my university, PhD students become candidates when they complete their candidacy, which includes their candidacy proposal, in which the student presents their research proposal to a committee (typically with members of their eventual examining committee) who must approve the proposal. My advisor reminded me that regardless of my own perspective on my research, the fact of the matter is that three or four years ago, a committee of experienced researchers, professors, etc., (i.e., my candidacy committee) reviewed my proposal and confirmed that the work it describes merits a PhD.

Based on that reminder, I framed by defense slides by beginning with a very quick review of the original candidacy, including a slide with a short problem statement. At the end of the defense, I pulled up another copy of that slide and addressed each point in the original problem statement, explaining how I'd addressed it. Then I followed with some "reveal text":

quod erat demonstrandum

My research involved a fair amount of proof theory and formal logic, so this was especially appropriate, but the point remains: the work that I presented was that "which had to be demonstrated". The experienced committee said several years ago that the proposed work merits a PhD, and I completed that work.

The point here is that it's not really the candidate's place to determine what merits a PhD. They haven't, at that time, enough experience to make that determination. The university and committee does, and has already decided what merits a PhD, and it would be entirely appropriate to respond to the question "What merits a PhD?" with "you, as a committee member, explained that to me some number of years ago, and I've fulfilled those requirements."

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    This arrangement with proposals and candidacy committees is not universal. Commented Dec 18, 2014 at 16:43
  • @kundor That's a good point. I've updated my answer to include a bit more description of the process for context. In institutions where such arrangements exist, I think that they are beneficial in this situation: if a student has successfully completed the requirements, there is no retroactive counterargument that the research isn't sufficient; that argument would have voiced during the candidacy examinations. Commented Dec 18, 2014 at 17:58
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    @Joshua: While they may be beneficial in this situation, I'm not at all convinced that they're a good idea in general, especially in my field (mathematics). That simply isn't the way I ever did research, before or after my doctorate. Commented Dec 22, 2014 at 6:43
  • @BrianM.Scott Can you elaborate a bit on your research methodology? I think we may have missed each other's points a bit, because I have a hard time seeing where it's not a good idea, whether in a formal setting or not, to have other more experienced people in your field at least confirm that "yes, the thing that you're thinking of working on is still an open problem, and it would be useful to work on it." Of course, I recognize that not every significant result can be predicted in such a way, but it seems like a bit of experience helping to avoid some dead-ends would usually be helpful. Commented Dec 23, 2014 at 17:22
  • @Joshua: I worked on whatever caught my fancy, because it was fun. In the case of my dissertation, a small problem led me to notice a parallel with something more familiar that suggested a host of related problems, many of which I could solve, but it came out of the blue. For the most part I didn’t set out to solve specific problems: I played with neat ideas to see what, if anything, would pop out. (And in my experience most published research simply isn’t very significant.) Commented Dec 23, 2014 at 22:29

The general requirement for getting a PhD degree is to produce novel research results (including of course writing them down in a dissertation and defending it in front of a committee). By this, you should show that you can work as an independent researcher.

one Professor was asking the defender why does he think, he deserves the degree.

If someone asks that during the defense, the answer should point out in which way the results are novel and a contribution to the current knowledge in the thesis' area of research.

  • 3
    "the answer should point out in which way the results are novel and a contribution to the current knowledge in the thesis' area of research." Agreed, but I also want to point out (and did, in another answer) that the candidacy committee declared however many years ago that the results of the proposed research (if executed successfully) would be novel and a contribution. The question at this point is only whether it was executed successfully. Commented Dec 18, 2014 at 16:09

For a Masters Degree, you are using existing knowledge and applying it to a new situation. For a PhD, you are creating new knowledge - you have discovered or invented something that was not known or existed before. If you can show that you have done this, you deserve a PhD.


Let's look at the abbreviation: PhD. Philosophiae Doctor which literally translates (my translation) as "Teacher of the beloved wisdom". (Doctor from doceo - to teach; philosophia from φιλος - dear, beloved and σοφια - wisdom or knowledge.

To be worthy of a PhD, you must therefore teach - which in the widest sense means add to the body of knowledge that came before. You are no longer learning - you traveled to the edge of the universe of knowledge, and boldly went where no-one had gone before. And - and this is a crucial element - you told stories of what you discovered when you came back.

The question is a good and fair one - and the answer should be obvious:

Through my research I have discovered [X,Y,Z] which I have taught the world through my publications and dissertation.

No need to blush - just state the facts.

  • 1
    Interesting how you mention publications. I know one faculty member who was personally frustrated by the lack of institutional guidance on "how much research is enough research (to justify awarding a PhD)." To address that, he devised his own standard: four published papers; all his students were told his expectations up front. It made sense to me at the time, and I've always marvelled that his idea hasn't gained more traction.
    – J.R.
    Commented Dec 18, 2014 at 10:06
  • @J.R. - a dissertation is in itself "publication " but the peer review process can add a bit more credibility to the claim of originality; further the act of writing papers helps distill the thought process and it's good practice for a future independent researcher. I agree that some expectation of peer reviewed papers is reasonable.
    – Floris
    Commented Dec 18, 2014 at 11:43
  • One thing he liked about papers was how they added a layer of objectivity to the criteria. How much research needs to be put into a dissertation? Those expectations can vary from school to school, from department to department, and even from advisor to advisor. His "four papers" criterion eliminated much of that subjectivity. Since the O.P. is explicitly asking for "possible answers to this [deservedness] question", I thought it was worth highlighting this. (I thought about leaving an answer, but your answer is pretty close).
    – J.R.
    Commented Dec 18, 2014 at 13:59
  • @J.R. - the "smallest publishable tidbit" can be indeed tiny, depending on your field and your choice of publication... And sometimes one giant contribution could be more than enough (think Brian Josephson en.wikipedia.org/wiki/Brian_Josephson - his prediction of the Josephson effect at age 22 got him a Nobel prize, but he didn't get the PhD until he was 24...)
    – Floris
    Commented Dec 18, 2014 at 14:04
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    -1 for beginning with the etymological fallacy; +1 for ending up somewhere reasonable nonetheless. Net result: no vote. Commented Dec 19, 2014 at 18:59

A couple of years a senior and well-respected scientist that I know personally told me his perspective regarding what the title PhD means to him. I try to take that with me since then, especially at times of self-doubt.

He said the most important message that the title PhD conveys is that the holder has survived a significant period of time (3-5 years depending on where you live/work) in the academic world, battling with self-doubt, uncertainties in work, questionable guidance/project management, and many more challenges.

So, the way I see it; if you have survived until the end of your thesis defence AND fulfilled all criteria set by the university (including original research), then you damn-well deserve the title and there's nothing anyone can fuss about. :)

Good luck with your work/defence.

after all it's the university that grants the title, and thus its the institution's responsibility to make sure that the titles they bestow upon candidates is up to the international standard. It's their reputation on the line, as well.


This question is not a check if you are over self-confident or anything the like. Simply provide arguments why your PhD work matches the acceptance criteria that a valid for that institution. Your supervisor should know.

If criteria seem not obvious for some reason, emphasize the scientific novelty (some details you have investigated first ever) and any scientific recognition of the results (accepted papers, attended conferences). Negative results that just disprove the initial work hypothesis may be near equally significant.

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