Every field has its own vocabulary, but oral defenses are more similar to each other than most candidates expect. Committees are, in the end, testing the same handful of things: whether you understand your own work, its limits, and what it would mean to do it again.
Why the same questions keep showing up
A defense isn't really an exam on your dissertation's content — the committee has already read it. It's an exam on your relationship to that content: can you explain it, defend it, and locate its weaknesses without the manuscript in front of you.
The core twelve
These show up, in some form, across almost every field:
- What is your contribution, in one sentence?
- Why this method, and not an alternative?
- What would you do differently if you started again?
- What's the weakest part of your argument?
- How does this connect to [a paper the committee assumes you've read]?
- What are the limits of your sample or scope?
- Who is this work actually for?
- What surprised you during the research?
- How do you respond to the obvious counterargument?
- What's the next study, if you kept going?
- Why does this matter outside academia?
- Is there anything you'd like to add?
A defense tests your relationship to the work, not your memory of it.
How to rehearse an answer
Write a one-sentence answer to each of these twelve before you write a paragraph. If you can't compress it to one sentence, that's the part to work on — not the part to over-prepare with more words.
Then say the sentence out loud, to another person, under mild time pressure. Reading an answer silently and defending it out loud under questions are two different skills.
The night before
Don't reread the whole manuscript. Reread your one-sentence answers to these twelve questions, and get some sleep. Committees can tell the difference between someone who knows their work and someone who memorized their manuscript the night before — and it isn't the second one who does well.