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What is a thesis defense and how does it work?

James Davis

Careers Commentator
Every student wanting to do a PhD has to face the thesis defense. We’ll walk you through what it entails and how you can ace it.

A thesis defense can be quite daunting, but if you know what it is, how it’s structured and how to prepare, you’ll have a good shot at acing it. This article is designed for students considering a PhD and want to learn more about what it entails, but could also be of assistance to current PhDs coming up on their own defense. 

So what is a thesis defense?

A thesis defense is basically a twenty-minute to an hour-long presentation, where you demonstrate knowledge of not only your own work but your field as a whole. This could mean authors that have come before you, to colleagues who’ve written on similar topics. You’ll be presenting in front of a ‘thesis committee’, which is usually a panel of professors. This panel can be decided in a number of ways, depending on the university. Institutions like ANU don’t even do a thesis defense, whereas others like VU allow you to nominate candidates to examine your work, which is then ultimately decided upon by your supervisor. Some universities even let you hand-pick the whole committee! So it’s worth checking which style your university employs. 

When does a thesis defense occur?

Generally, after your thesis has been submitted. They can’t talk about your thesis if you haven’t got one after all! In cases where a thesis defense is secondary or non-existent, your thesis is presented to two or more qualified evaluators, who then make the bulk of their judgement on the work. Not on your rhetoric! This should come as a relief if public speaking isn’t your forte. Even so, it’s worth practising up! It can’t hurt to make a solid impression. You’re a subject matter expert after all. 

How do you succeed in a thesis defense?

No matter who’s evaluating you or what discipline you’re in, there are some general guidelines to follow. We recommend bolstering these by getting your supervisor’s advice and/ or the experiences of your peers. 

  • Do your prep work. You may have written your thesis, but you need to know it like the back of your hand to defend it adequately. It also pays to know exactly where the weaknesses are so you can address them. 
  • You’re not required to argue your case or anything as the name may imply. You’ll just be asked questions, so be as informed as possible about your work and iron out any objections and preempt uncomfortable questions with prepared answers.
  • Practice possible questions ahead of time. This entails coming up with questions you might like to know if you were in the committee’s position. You can even get a friend to help and practice it like you would a job interview. If not, just practice answering while you’re in the car, with all emphasis or annunciation you intend. 
  • Practice speaking in front of a mirror. Notice your body language and whether or not you appear nervous, or have distracting habits like scratching your chin too much or swaying side-to-side. These might seem silly, but you’d be surprised how common these unconscious behaviours are! Practising in front of a mirror can help you associate how you appear to others with the way you’re feeling and adjust. 

That’s about the gist of it! Remember: this is basically a formality. Going into your thesis defense doesn’t need to be daunting, as they’ve already made their decision. Just do your best to appear relaxed and comfortable. Let prep work carry you through and you’ll walk out with ‘Dr’ appended to your name!

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