How to defend plagiarism in master's thesis

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If you submitted a thesis with plagiarism, the typical consequence would be expulsion. You would not get a degree. The good news is you didn't submit it yet, so there might be no consequences.

Can you still change your thesis? You need to ask your supervisor.

You have admitted there was plagiarism in the draft. Stick to that. Just make sure there is no plagiarism in the final version. Your defense should that you did the wrong thing in the draft and have fixed it; the final version does not contain plagiarism. You will still look bad, but I think avoid punishment.

Health problems are never a defense against charges of plagiarism. Continue to get treatment from health professionals.

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Have you submitted your paper yet?

If you have not yet submitted then you haven't done anything wrong (yet!) and you have time to change it. If required you may have the option to ask for a deadline extension, given the current exceptional circumstances and your own health issues.

Reading your question I'm not 100% clear what you've actually done or how much of your thesis could be considered plagarism.

• If you've failed to attribute a couple of theorem definitions then this should be easy to fix; either re-write them in your own words, or quote them, and cite all sources properly*.
• If you've copied (even in translation) large portions of discussion and analysis then you'll have more work to do, but it's essentially the same job as you've had throughout your thesis: You need to express these ideas in your own words and convey your understanding of them.
• If the writing is your own, but you are worried that the ideas are not as original as you have portrayed then you may not have such an issue. Provided you are submitting your own work, then a masters thesis does necessarily not need to contain entirely "new" proofs or results. If this is your concern you should talk to your supervisor and understand their expectations (and the marking rubric) for a thesis, if they have read your draft and are broadly happy then you may not need to do anything further.

If your thesis has been recently submitted then you should talk to your supervisor as soon as possible and explain clearly what has happened. It may still be possible to retract you thesis and further you may be able to talk to your academic institution and arrange for an extension and re-submission date when you can submit a plagiarism-free version. This will be a discussion between you, your supervisor, and your academic institution, the outcome of this will depend on the precise details of what has happened at what stages.

If your thesis has been submitted and plagiarism has subsequently been found during the marking process. This is a very different situation from the above. You should read up on the policy of your department and the broader institution. You may wish to edit your question/ask a new one in order to get more specific advice, you will need to provide further details as to how much was plagiarised and how exactly it was copied (short phrases with minor changes or entire paragraphs etc.).

General advice on discussing health and it's impact on your work Current issues surrounding COVID and your personal health are not an excuse for plagiarism, but they may be a valid reason for delaying a submission until you can remove the plagiarism and submit a legitimate thesis.

*Edited for clarity, you should always cite sources properly, not just when quoting!

Admitting your mistake is the 2nd step in fixing things (finding the mistake is the 1st), and the 3rd step is making sure the mistake doesn't become a problem by fixing he mistake. There are lots of minor steps (which usually change based on the situation), but I've found these are the 3 major steps to get a situation back on track.

We're all human and can rush through even important things. Use this as a learning experience to prevent doing it again.

You shouldn't defend the plagiarism, just admit the mistake and correct it, which it sounds like you are willing to do, if you haven't fixed the issue already.

The things that caused you to make this mistake can all too often be used maliciously as excuses for bad behavior. Don't fall into that trap. Even if they are true, it'll likely be taken as an excuse, rather than a good reason. We've all been affected by changes in our lives due to Covid-19, so there's a little more leeway for things like this getting in the way, sometimes. But that's still not a good reason for making career ending mistakes.

If you haven't already, you should apologize to your advisor for the mistake and reassure them it won't happen again. You can state that it was unintended, but unless you can somehow prove it, like you said you could with the reference in the appendix, then it likely won't reduce the lost trust.

This is a case of "take your lumps" and learn from it. It'll likely take less time and energy than anything else. You "did the crime" so you should "do the time". Because it done was accidentally (intention often matters in law) and you haven't submitted this as a final draft, your crime isn't as serious as it could be. Defending it would make it more serious, so just don't do it. The "time" usually depends on the severity of the crime, so you've lost trust from your advisor, which is a lighter sentence than another Answer mentioned about expelling you. Just work to regain that trust, even though it might not ever be regained, and try to make sure you don't give them another reason for them to lose trust in you.

Martha Stewart is a good example of this. She was convicted of insider trading and, for the most part, did her time and got over the whole ordeal fairly quickly. She could have made a huge deal of trying to save her fame and fortune by putting up a massive fight, but instead she only did what seems to be a perfunctory fight against the charges. She ended up doing her time in prison fairly inconspicuously, then her home confinement without making a big deal of it. She might not be as big of a deal or as much of a "household name" as she could have been without the problem, but she's still around.

There's plenty of people who have made a huge deal about charges against them, only to make things worse. Don't do this to yourself.

As for your feelings about what happened, well, you'll just have to deal with it. Forgive yourself if you can, understand that it was a mistake that you fixed, and over time, it'll feel less like you've done something "horrendous". It could have been worse, but it was caught before that happened. Again, use this as a learning experience. You are allowed those. I know what I'm saying isn't exactly comforting right now, but that'll just take time to dull the edge of what happened. That's normal.

It's actually a good thing you are reacting like this, even though it doesn't seem like it right now. Your feelings will help prevent you from making the same mistake later, due to "never wanting to feel like that again". Just take some time to calm down. In a few years, you'll look back at this as a lesson learned and pretty much everyone else will have forgotten about it.

Edit:
I'm not saying to not defend yourself, just defend the correct thing. Don't defend the plagiarism, defend that you did it accidentally and are willing/working to fix it.

Edit 2:
Also, when you go to defend your thesis, don't bring up this issue, as it'll simply confuse your defense. The people on the Board/Panel/whatever, will either know the situation and bring it up, or they won't. If they do bring up the plagiarism, stick to defending the accidental nature of it and point out that it's fixed.

You can say that you've learned you lesson and that it'll never happen again, but that can come off as a simple placating gesture, rather than an actual fact. They've probably heard the same thing from others that end up making the same mistake they promised would never happen again. It's possible to make this type of statement sound real, but it has to be said with real conviction, since the tone of your voice and your bodily actions can speak just as loud, or even more loudly, than your words.