[gbrown]

You do not have the experience or expertise to justify your claims; a PhD thesis is in no way like doing a regular research project, or passing a course in university.

The reason why failing a PhD thesis defense is rare is because your adviser should prevent you from defending until the product is sufficiently strong. Many, many, many more people fail by dropping out of a PhD program during their dissertation than fail by doing a poor defense. Comparing successful thesis defense rates to startup success rates is not valid.

[semi-extrinsic]

> The reason why failing a PhD thesis defense is rare is because your adviser should prevent you from defending until the product is sufficiently strong.

This. Failing a public defense is not like a startup failing, it's more like an IPO failing (as in, stock goes to zero within a short time). You don't do it if you aren't 99.9999% sure it won't fail.

[dnautics]

It's worth noting that some PhD students get passed because their advisors feel bad for them after they drop 8 years in the program and the advisors are too incompetent to actually bring up a student through the PhD with a successful project.

I've seen it happen five or six times (usually it's the same group of professors) at a top-tier research institute.

[tjl]

The external examiner should allow that to happen, if they're doing their job. The whole point of the external examiner is so professors can't just collude to pass people.

I've seen a number of things happen during a defence, but not this. The worst was seeing two professors (one of whom was the candidate's supervisor) on the committee argue with each other while the candidate just had to watch. It took a lot of work for the chair to reign them in. I think it was difficult for the chair because they were arguing in German and the chair didn't speak it since he wasn't from the German department (my friend was getting her Ph.D. in German literature).