I recently defended my master thesis. One thing only went wrong: I said a certain method was rather new (which it was!) and the most senior professor in the room (my supervisor was not there, he had an unexpected meeting) contradicted me, telling me that it was old and had been done in the lab for ages. Honestly, I just gave in. He seemed so sure and I did not dare contradict him. However I was sure before and of course I have since checked, the method is indeed new, the professor was just plain wrong. What should I have done in the situation?

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    I'm not a fan of that style but it wouldn't be unheard of for someone to say something like that on purpose (knowing full well that their statement is wrong) to get you to defend your background knowledge. Commented Mar 27, 2016 at 23:16
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    BTW, "unexpected meetings" of advisor during a student's thesis defense are nonsense. Although, hopefully, most thesis defenses are pro-forma, the advisor needs to be there to be sure that nothing goes wrong unexpectedly. No one would quibble if someone says they're doing to their student's defense. Jeez. Sounds bogus... Commented Mar 27, 2016 at 23:30
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    I agree with @paul garrett: the person in this situation who most unambiguously behaved poorly is your thesis advisor. Why not give the most senior professor in the room the benefit of the doubt that his feedback was sincere but mistaken? As to what you should have done: you passed your thesis defense and you looked into the feedback you got, so....great. Congratulations on your degree. Commented Mar 28, 2016 at 0:00
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    I suppose it's not impossible that it was some kind of test, although I've never experienced or heard of such a thing. It seems much more likely to me that the professor genuinely thought that the new method was the same as the existing one, most likely due to misunderstanding the description of the new technique. This is something I have experienced, on a regular basis. It's easy to deal with if you can spot the misunderstanding and correct it, but if you're not that lucky it's always tricky.
    – N. Virgo
    Commented Mar 28, 2016 at 3:07
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    I know less than nothing about the topic, but a quick search shows that the CRISPR part of CRISPR/Cas goes back almost 30 years, and the cas part was identified almost 15 years ago. Perhaps that's what he was referring to, and not the joint Doudna/Charpentier work that is from only 3 or 4 years ago. That is, maybe the senior prof hasn't actually read your thesis, but recognized the names of the parts of the method as not new, and didn't understand from your defense that the work combining them was new. I don't have a new answer to add, so I'm upvoting the "be gracious and move on" answers.
    – shoover
    Commented Mar 29, 2016 at 14:26

11 Answers 11


the most senior professor in the room contradicted me

This may happen due to any reason.

(my supervisor was not there, he had an unexpected meeting)

Probably, your supervisor was clear about his decision regarding you and the rest was just a formality (which actually happens in some cultures). So he chose to skip that ceremony (and attend that unexpected meeting) because he knew his decision would matter alone.

What should I have done in the situation?

Assuming that your supervisor had a green signal in his mind for you (which, of course, you can guess from the situation), you should have done nothing but tried to pass on with any reasonable negotiations.

Even if the above assumptions are wrong, you should have still done the same, because, considering your this statement:

I said a certain method was rather new (which it was!)

Especially, which it was! part, nothing can go wrong.

Of course, the reasonable negotiations would involve, you trying to defend that with solid arguments and references, while at the same time humble enough to listen to his criticism and show respect to get along.

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    "Probably, your supervisor was clear about his decision regarding you and the rest was just a formality (which actually happens in some cultures). So he chose to skip that ceremony (and attend that unexpected meeting) because he knew his decision would matter alone." - The role of the supervisor at the defense is generally not to make a decision about whether to pass the student, but rather to support the student.
    – ff524
    Commented Mar 30, 2016 at 3:55

Did you pass your thesis defense? If so, it's all water under the bridge.

If it is eating you up inside, you could send a polite note to the senior professor (cc:ing your advisor) thanking them for the question and that now that you've had a chance to re-check things, that you are ever more certain that your method is different from the suggested prior method because of x, y, and z; but perhaps you misunderstood his question and there was another earlier method he was referring to, and if so -- could he please send the reference? (tip of the hat to @gnometorule)

If you go this route, I would frame it as a letter of thanks, appreciation, scholarly inquiry, and to keep the tone as non-accusatory as possible. As @guifa notes, some jerks professors view thesis defenses as a type of hazing -- a no-holds-barred opportunity to test your mettle; and what happens in defense should stay in defense. You do not want to drag this out. It can easily blow back in your face or the face of your advisor if the senior faculty member has a thin skin (which unfortunately many academics seem to have).

Again, if you have your Masters, then I would just be happy with that and just make rude gestures towards that senior faculty member from the safety and privacy of your own home. And don't ever do this when you become that person in a position of power.

You changed the question slightly from the initial posting from [what to do after the fact] to [what you should have done at the moment]. As note above, all questions at thesis defenses are fair -- even ones that are built on false or falsified premises. It is, after all, a "defense" and as a scientist you should be able to defend yourself from both truthful and false/falsified statements without having to resort to ad hominem counter-attacks. You respond based on your training and experience what you believe to be correct. And obviously given that you passed the defense, the examiners thought that you gave satisfactory responses on the whole. As Queen Elsa teaches us, let it go.

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    Valjean, experienced people know how to sound sure... even when they are just bluffing. This kind of (all-too-typical) noise and hazing is less disturbing than the fact that your advisor found a reason not to be in attendance. Commented Mar 27, 2016 at 23:31
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    I do not think he "found" a reason, the guy is notoriously scatterbrained and well known for it. On top of it, he does not have a secretary and is notoriously difficult to reach (rarely in office, does not read emails) so it is quite realistic he forgot.
    – Valjean
    Commented Mar 27, 2016 at 23:46
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    @Valjean: Ask for a reference, and not just as a snide remark because it could, still, be quite possible that he was right, not plain wrong, or mock-confrontational: if your method, say, is new but in spirit similar to an existing one, maybe it was an off-hand remark to that sort. In any case, I'd say something like "Very interesting...I honestly believed this method to be novel. Could you give me some reference so I can read up on the prior work you refer to - now or per email later?" Commented Mar 27, 2016 at 23:57
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    "it could, still, be quite possible that he was right." Indeed. In my own field, I've seen a several papers claiming to have discovered something new that had been published in a standard textbook back in the 1940s or 50s. I guess most grad students just don't read 60-year-old textbooks! There's rarely anything to be gained by telling the re-discoverer about it, unless you enjoy trying to win an argument for its own sake.
    – alephzero
    Commented Mar 28, 2016 at 2:09
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    I guess you are talking about CRISPR/Cas9 as a method of genome editing, which has been around for about 4 years now, but got a lot more popular last year. In a way he's right too. The original publication is from 2012. science.sciencemag.org/content/337/6096/816 And the general study of CRISPR/Cas systems in nature has also been around for a while before the use for genome editing/silencing started.
    – skymningen
    Commented Mar 29, 2016 at 9:31

Forget about it and go on with your day.

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    The question was "What should I have done in the situation?" This seems to be an answer to a different question "What should I do about it now, after the defense?"
    – ff524
    Commented Mar 28, 2016 at 7:55
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    No, this answer definitely suits the original question as well. Which is, in fact, what the original poster appears to have done. Commented Mar 28, 2016 at 13:28
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    Second great one-liner in the academics.SE site, but unfortunately, SE dynamics wish for the explanation on why the one-liner would be appropriated to the matter at hand, thus the low vote count. Commented Mar 28, 2016 at 14:01
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    @Mindwin Seems to me that sometimes, the best thing to do about an unfortunate "SE dymanics wish" is to forget about it and go one with your day. ;-)
    – Dronz
    Commented Mar 29, 2016 at 20:44
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    @JesseWilliams no, this answer doesn't suit the original question at all; it is dismissive and unhelpful interpreted as such; and no, the OP clearly didn't "forget about it and go on with eir day" then or now-- the OP is instead pondering how ey could have most constructively behaved if ey had to do it over again, presumably with the goal of cultivating skills with which to respond most constructively when faced with similar situations in the future. I find this to be a laudable goal and a great question since I place a high value on such skills and wish to cultivate them in myself.
    – Don Hatch
    Commented Mar 30, 2016 at 9:26

Generally, when faced with questions or comments like this one, you need to respond in a way that is open to the possibility that the professor is right, but that nonetheless demonstrates your belief in your own position. Don't give ground too easily, but don't get too entrenched either, since you need to be open to new information.

How you do this depends on how specific the professor's comment is:

  • If it was just a vague contradiction - "That's not new, it's been around for ages" - then you need to probe for more information. "That's interesting, I've not come across any previous use of this method - could you tell me more about where it's been used?".

  • If prof responds in detail ("It was done by Professor X in paper Y") and paper Y is not one you've come across, then your response is similar. "That's really interesting, I will look into that. Perhaps we can discuss this further after the talk." Or you might be able to second-guess the method used even if you don't know paper Y. "If they used method Z, then it's related, but our is different because..."

  • If paper Y is one that you are familiar with, then you have something concrete you can discuss. "That's certainly an important method, and provided inspiration for our work [if it did], but I referred to our method as new because it has these important advances/differences..."

However rude the professor is with their comment, it may still be a valid point, so try not to take it personally. Ignore the tone and just respond to the substance as politely and scientifically as you can.

Finally, it's easy to say all this in hindsight, but when it's early in your career and you're faced with an imposing figure contradicting you, it is only natural to give ground under pressure, and the fact that you successfully defended your thesis shows that you coped well with the overall situation!

  • Honestly.....it was the first: "That is not new, we have been doing that here for ages". I know that to be wrong, but asking him where it was used as you suggest would seem rather rude to me.
    – Valjean
    Commented Mar 28, 2016 at 9:33
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    I don't think it needs to be rude. You just need to adopt an attitude of "I'm intrigued to know more because I wasn't aware of this". It's just scientific curiosity, so long as you don't imply with your tone of voice that you mistrust his information. Commented Mar 28, 2016 at 9:39
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    knowing full well that he could not possibly give a satisfactory answer (because he was plain wrong)? sighs......maybe I am too much into "never confront a monarch in public"
    – Valjean
    Commented Mar 28, 2016 at 9:45
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    I agree that it's not easy, and your response was a very natural one. But I think that pursuing a discussion is the response that is truest to the spirit of a thesis defense, and to scientific discourse in general. And a professor would not have reached their position if they weren't able to handle someone disagreeing with them. Commented Mar 28, 2016 at 9:50
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    This seems like the best answer that actually addresses what should have been done in the moment.
    – DCShannon
    Commented Mar 28, 2016 at 16:23
  • Option A - Argue about it in front of an audience and focus attention away from your real presentation. Focusing on proving the senior professor wrong in front of an audience is not going get you anywhere.

  • Option B - Let it go. Go research it again thoroughly on your own. If you think it's a new approach, gather your research papers that support your claim. After you do your specific research, kindly ask the senior professor for examples of clarity on his comment. (Don't go in his office and slam a paper in his face proving he is wrong.) Go see him in person. Don't send an email because emails have no vocal tone to them.

Overall, I bet that it is not a 100% black or white issue. Perhaps the professor or you are thinking of a "similar" method or a method that goes under a different name. You may call it binary and he calls it base-2.

It's no big deal. Some people just like to speak up and make comments no matter what the situation. The senior professor probably won't even remember what he said after one week. Nevertheless, it is a good learning experience. You get to practice how to deal with confrontations that you were not prepared for.


People (including professors) make mistakes. I have been mistaken myself in similar situations as you described, and would not attribute any kind of malice to the professor's remark during your defense. As @RoboKaren pointed out, you got your degree, and it is mostly water under the bridge now.

In case it irks you a lot, I would recommend not to send an email to the professor, but to talk to him personally, maybe phrasing it as a misunderstanding regarding the scope of the method. An email might come off as somewhat aggressive.

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    I completely agree here. If you (@Valjean) get any chance to just casually "out of interest" talk with the Professor about the method in question again and possibly learn that (a) either he misunderstood which method you were referring to or maybe (b) it actually had been published long ago (things get republished in science all the time), it may make you feel better about the whole thing.
    – Chris
    Commented Mar 28, 2016 at 7:26

Two actions should be taken:

A- Forget about it. Say Thank You and move on during the meeting.

B- Make very well sure that you're right and he's wrong before just assuming you're right. I've seen (and refereed) many cases where someone just knows something is novel when its not. This can happen for many reasons. Keep in mind that this person has been around longer than you have, may well have a wider understanding of the literature than you have, or have an inkling that something that has historically been presented in a slightly different way is exactly what you're talking about but is a little difficult to make the jump.


"Honestly, I just gave in. He seemed so sure and I did not dare contradict him."

You have answered your own question - you shouldn't have done this. If you were sure of yourself and your facts then you wouldn't have given in and you would have contradicted him. You are allowed to disagree with "senior professors" - they make mistakes too. That you did not suggests to me that you weren't sure of yourself or the facts.

Part of these occasions is to test whether you have the self-confidence to know your discipline, know when you are right and to argue your case.

Of course, if you were wrong...

  • I agree with @Rob Jeffries. One purpose of a thesis is to state your case against argument so that you are on an equal basis. The prof was just doing his job. In your position I would have asked him to clarify his statement and to justify it, just as you need to for yours -- from an equal basis.
    – r3mnant
    Commented Mar 29, 2016 at 1:42
  • I wouldn't blame the OP for not being sure he is right, as sure as you are that your method is new, it's easy to think "this professor has a lot of experience, maybe he knows something I don't" when you're being directly contradicted
    – Ovi
    Commented Mar 29, 2016 at 13:39

When people disagree about facts, the only useful procedure to solve the disagreement is to appeal to an outside source that is accepted by both parties.

Typically this is not feasible to do in the middle of a presentation, either because such an accepted outside source is not available, or even if it was (say through an internet connection that is active on the spot), it will take away time that is scheduled otherwise. To the degree therefore that rebutting the claim is not essential and/or critical for the purpose at hand, you, as the presenter (and so the one with the higher stakes in the situation), should wisely let it pass.

But it would be a peaceful way to go about the world if you contacted the other party afterwards, by say, an e-mail that would supplant the necessary information about the matter. It is not about you triumphing over him or truth triumphing over falsehood, -it is about helping another person to not make the same mistake again.


While I believe user2390246's answer should be the preferred way to handle this kind of situation, I think the safest path would be to acknowledge the contradiction and quickly move on.

That's interesting, I've not come across any previous use of this method, but I'd love to know more. Could we discuss this afterwards?

If they decide to press the issue, user2390246's answer has the details how to handle that, but I'd be willing to bet they won't.

If they agree, then obviously do approach the professor sometime later (preferably in person, during their office hours, after double checking your facts).

It should be noted that this only works if the method isn't central to your thesis and the contradiction doesn't directly threaten the validity of your results. If that is the case, then you have no choice but to push back.


This was your defense. You should expect senior faculty to give you challenges and questions like this, because they want to test the limits of your knowledge and usually won't be satisfied until they've gone beyond them. How far can they go before they reach "I don't know?" When you get there, do you have what sounds like a reasonable strategy for how you would find out or resolve a question?

When you get a challenging question like that, the first thing to do is listen and make sure you really understand what the question is asking. Reflect it back to the asker to be sure and to demonstrate you've got it. Then, figure out if the challenge/question is something that is core to your thesis, or a side/auxiliary point. If your main claimed contribution is this allegedly novel method, and the method not being novel would mean you don't have a contribution left, that's a core issue. If you just used the method and the results of it are what's important, and you only mentioned in passing that the method is relatively new, then it doesn't matter so much. Consider saying what you know and offering to continue the conversation "offline" or afterward, when you can find out more details about the citation. With other sorts of non-core questions e.g. about your method or result you can use a response like "I'll have to look that up and get back to you on that." This helps keep the conversation focused on the core elements of your thesis.

More important for the defense, consider and respond to how it would affect your work if the questioner's point is accurate.

For example,

As far as what I found < maybe add, and this is what I did to look >, I believe the method is relatively new. If it's actually been used for a while, that increases my confidence in the reliability of the results it produces and could help make the conclusions even stronger. Thank you for letting me know about this and I'd be glad to continue the conversation afterward to discuss more details."

If he takes you up on the offer to get more details, try to get pointers to authors or papers where you can check. Claims of novelty are much easier to disprove than to support, conclusively. You may still be right, but you're not going to prove that in the moment of the defense presentation nor do you necessarily need to. You need to show how you respond to this potential new information and what knowledge you assert in your response, including some analysis of how that (counterfactual or not) would affect your thesis.

Finally, if you already passed the defense, you can just view the professor's challenge as part of the challenge of a defense, and congratulations on having passed through that process successfully.

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