The first time I participated in a public viva I was very sceptical. How could I really rake over the issues and probe the thesis’ weak spots in a public forum without boring the audience or embarrassing the candidate?
Public vivas are not, of course, the practice in the UK, but they are very common across the Continent, and I believe there is a strong case for importing them.
In practice, I found my concerns easy to circumvent. The key was to put my questions on slides. These allowed me to make my questions clear to both the candidate and the audience, allowing us to keep on track and avoid any misunderstandings.
The great advantage of having an audience is that it allows the public to see that scientific debate is thorough, and that standards are high. While non-experts may not follow everything, they will get some appreciation of the level of debate, which can only increase their respect for holders of doctorates.
Transparency also allows scrutiny of examiners, restraining any poor behaviour or bias. This is a major concern of candidates, and eliminating it, I believe, would more than compensate for the potentially greater pressure of defending in public. It would also remove the need for an independent chair, a measure some UK universities have adopted to prevent excessively aggressive questioning from examiners.
There is considerable variation in the practice of public PhD defences across the Continent. Two-thirds of the 21 members of the League of European Research Universities require prior approval of the thesis before proceeding to the defence, and just under half treat the public defence as a merely formal confirmation. The most common number of examiners is three, with more than half of universities allowing the candidate’s principal supervisor to be on the jury.
In the Netherlands, for instance, the panel consists of seven academics (including two international members, on the occasion I served as an examiner), and the exam lasted exactly one hour. International members got two questions and everyone else, if they were lucky, got one. This was certainly a ceremonial event, rather than a real exam.
At universities in Flanders, the thesis is approved in advance, and there is an initial closed exam in which the jury can ask for major changes and delay the public viva. In Scandinavia, the thesis is approved in advance but the public defence can still be rigorous and thorough. In one case I asked for major changes and an extra chapter before I approved the thesis and agreed that the defence could go ahead. Once that was done, the candidate defended himself well in the viva. Practice in France varies; although it is sometimes a formality, the public defence is often a thorough debate.
Anecdotally, it seems that failure at the public defence is very rare, even at universities that do not treat it as a mere formality. However, I believe that to ensure high standards are maintained, it is important that the possibility of failure exists, just as it does for any other exam. Even if the thesis is judged acceptable, a candidate must be able to defend their own work, so the possibility will always remain for embarrassing moments if they patently cannot. But provided candidates are properly prepared (and those not making progress are encouraged to stop before writing up) such moments should be mercifully rare.
Of course, if public viva defences were to be adopted in the UK, they would require more effort and cost to organise than vivas currently do. Moreover, examiners initially might be a bit nervous about signing up to public scrutiny, so some training would be required.
But given the international nature of doctoral standards and increasing PhD student mobility, it is time to discuss seriously the idea of throwing open the doors of the UK viva. After all, what could be a more fitting way for a candidate to cap off three or more years of hard work than by demonstrating their mastery of their subject not only to experts but also to peers, friends and family?
David Bogle is professor of chemical engineering and head of the doctoral school at University College London. He is also chair of the League of European Research Universities’ Doctoral Studies Community.