Yes, it can happen for multiple reasons. I have personally seen it fail once: a PhD candidate in physics was asked a random but basic question about quantum physics, he couldn't answer, and the committee "voted" no.
From what I have seen, it is more common for people to simply quit their PhD candidacy once they form their PhD committee, because the committee members will ask for a soul crushing extra amount of work before the defense (happened to two friends of mine).
Re:The PhD pioneers
by selimthegrim on Friday December 08, 2017 @06:44AM
(#15878107)
What was the question?
Re:The PhD pioneers
by ApostleMatthew on Friday December 08, 2017 @08:03AM
(#15878371)
My former adviser told me that out of the 150+ committees he's been on, only one failed, and that the person who failed known for stealing research from his labmates and demonstrated in the defense itself that he didn't know what he was doing.
As far as I'm aware, defenses at most institutions are formalities. Your adviser has already decided you're done and its just the bureaucracy. Some places don't even have defenses (I don't think Berkley does, at least the chemistry department).
I didn't get the nervousness of the defense. I was nervous about doing something embarrassing, but not actually of passing.