Why do some institutions have a Pre-Defense for PhD degrees?

Question

The process of acquiring a PhD degree at my institution (after successfully completing comprehensive exams) is as follows:

1. Submitting a research proposal and defending it.

2. Approving the proposal by a committee where they will be the committee members who will be present at the final defense.

3. Completion of the dissertation and extracting at least one paper from the dissertation and publishing the paper in a journal.

4. The student can do Pre-Defense after at least one year since the approval of the proposal.

5. Doing the final defense after a successful Pre-Defense.

In my institution, a PhD student has to publish at least one paper extracted from his dissertation in order to be eligible for proceeding into a Pre-Defense. The Pre-Defense committee must approve the work done by the student and if the work does not get approved, the student needs to wait a while, and then he will be able to do the Pre-Defense again.

In my opinion, the Pre-Defense is redundant since the paper is peer-reviewed by experts before it gets accepted. So why is there a need for a Pre-Defense?

Answer 1

One of the comments seems to distill OP's question:

publishing a paper for me seems to be a Pre-Defense already. Why is there a need to conduct a Pre-Defense again?

It seems that OP thinks that peer review and the "pre-defense" are redundant, rather than the pre-defense and defense being redundant. I think this is probably the wrong way to think about the pre-defense. The thesis committee is not deciding again whether OP's paper is suitable for publication in some particular journal: that's the job of that journal's editor. The thesis committee is deciding whether OP is prepared to graduate their PhD program.

Having a paper published is indeed some sort of stamp of approval, but it is not a magical one. Peer review is deeply imperfect. Many journals pretend to provide peer review but actually publish almost everything they receive because they want the publication fees. Peer review can also be undermined by conflicts of interest in the reviewers, just plain lazy review, or sloppy work by the editor. A lot of junk gets past peer review.

From what I can tell, a published paper is only necessary at OP's institution for graduation, but that does not mean it is sufficient. If there is some reason that the published work is not considered sufficient by the committee, it certainly makes sense for the committee to make this known to the student before their final defense. Additionally, requiring one published paper does not mean that the rest of the content is unimportant to the committee. They may expect some other number of publishable (even if not yet published) papers to be found in the dissertation. It seems like this Pre-Defense process would allow the student to be made aware if the committee finds the rest of the dissertation acceptable or not.

At my own institution, there was nothing called a "pre-defense", but these sorts of issues were instead handled through regular (approximately annual) meetings with the thesis committee throughout the PhD. The important point is that the student should be aware about their progress to degree and should not be ambushed at the final defense and find out they are not actually prepared to graduate when they expect to be.

Answer 2

If a "pre defense" occurs after the dissertation is complete, then it might be just a way to give the candidate advice on their work and permit them to make changes before a "final" defense.

In some places, a "final" defense is truly final. Failing it means no degree and no possibility of continuation. The student would like some feedback prior to that so that they can bring the work up to the proper standard. One hopes that the advisor can do that well enough, but it can also be useful, and important, to get independent advice from a committee, especially if that advice can lead to improvements. This might be the intent within your system.

However, if one can fail (finally) a pre-defense, the intent may be to weed out inferior and unlikely-to-succeed work, freeing institutional resources. If it is up to the student as an option, however, then I doubt that this would be the case and the prior suggestion more likely.

The required paper is, I think, also a way for the university to get outside independent assurance of the quality of the candidate's work via the normal review system of reputable journals.

I was once part of a less formal system, where the "defense" might result in acceptance, or "back to the drawing board", with a future review planned. Failure was rare unless the student gives up in making necessary changes or argues for incorrect results. I don't remember a case that required more than two iterations to success.

Answer 3

After your edits, it sounds like the process is roughly:

1. Do the actual work, publish it, and write your dissertation.
2. Have a pre-defense where (some subset of) your committee agrees that you've checked all the boxes for graduation, including having published a paper.
3. Have an actual defense, where your committee will confirm that your work is sound and significant enough to merit a PhD.

Given this, I think the second step is merely procedural. Imagine how frustrating it would be (for you and for the committee) if you went through the full defense, passed, and everyone thought you were done, only to learn that there was some issue with your publication, or your coursework, or some other technicality that would delay your graduation for months or even a year. This will lead to bad feeling, and the committee may feel some pressure to lower their standards rather than inconvenience you. Whereas by doing this pre-defense, such issues will be caught before your defense is ever scheduled, and everyone will agree in advance that you are good-to-go after you pass the defense.

Answer 4

I imagine there's a lot of variety in the reasons for introducing a pre-examination, but one which is missing/not highlighted in the other answers is that the countries I know that have a PhD Pre-examination are those where it is very uncommon to fail the final defense. In the Netherlands for instance, it is so rare to fail at final defense, that when it happened that a student failed a PhD defense a few years ago in Tilburg, it made the national news!

In these cases, where the final defense is a ceremonial occasion, where the possibility of failure is slim to none, it is, I believe, good to have some form of pre-examination. This performs a final check that the candidate has reached the required level. In some places this is done solely on the written thesis (for instance, reading committee approval), in other places a pre-examination defense and I'm sure other places have other systems I am unaware of.

I hope this supplements the other great answers here with a different perspective.

Answer 5

One peer reviewed paper is presumably only a relatively small part of the research described in your dissertation, so even if it was published in a good journal, the peer review of that paper does not constitute review of your whole PhD.

This will vary by field, but in my field, a PhD thesis should contain enough publishable research for 3-5 good journal papers, though it is not expected that they will all have been published before the thesis is submitted.

Some universities require a pre-submission defence with a committee internal to the university before students are allowed to submit a dissertation for external examination. The internal pre-submission defence is to ensure that the student is ready and the work meets the university’s internal standards before it is finalised and exposed to assessment and criticism by world experts. If the student is not ready, they will be given a chance to make revisions before the final (perhaps public) examination or defence.