I never had a dissertation defense. My department had abolished them sometime before I arrived as a graduate student, and I considered myself lucky compared with friends at other universities who had to endure what I imagined as a painful ordeal. So when the time came, my two faculty readers signed a form approving my dissertation, and I walked the bound manuscript over to the registrar and submitted it. That was that.

The first defense I ever attended was as a professor. Only then did I realize what I had missed. I led a dissertation committee for the 14th time recently, and for the 14th time I was filled with appreciation of the wonderful things that defenses do. The student passed, of course—failed defenses turn up in the United States about as often as hairless porcupines. But the purpose of the dissertation defense goes way beyond whether the committee turns thumbs up or thumbs down.

Universities have been awarding doctorates for centuries longer than the United States has been a sovereign nation, but graduate students have been writing dissertations and defending them for only the past 200 years or so. The practice evolved in the early 19th century in Germany, where so many of the customs and procedures that guide American graduate education first saw light. As William Clark recounts in his thoroughly informative Academic Charisma and the Origins of the Research University, dissertation defenses were originally conducted in Latin. These \”disputations\” were held in public and open to all interested parties, a custom that survives now in the form of posted announcements in advance of scheduled dissertation defenses.

Defenses could attract large crowds in 19th-century Europe, but in the United States today, they tend to be intramural affairs, attended by graduate students and sometimes faculty members in the dissertator\’s department. Sometimes the candidate and the committee have the room to themselves.

In the sciences and mathematics, a dissertation defense centers on a performance by the student, who presents his or her findings in a lecture format followed by a question-and-answer session. It\’s essentially a teaching display, not a shooting gallery in which expert faculty marksmen fire hollow-point questions at the candidate.

A dissertation defense in the humanities and social sciences looks and feels different from its scientific counterparts. It resembles an examination in which the candidate is questioned closely about work that the faculty committee has read in advance. Although the structure—a rigorous conversation—may resemble an oral comprehensive exam, the tone departs from that earlier and more stressful ritual. The plan is not to roast candidates on a spit; they are instead gently warmed, encouraged to elaborate on what they know.

More than 50 years ago, Bernard Berelson noted, in a study of American graduate schools sponsored by the Carnegie Corporation, that the dissertation defense \”is now mainly a form\” and not a \”real examination.\” True enough, but that doesn\’t make it a bad thing. There are already plenty of barriers that professors place in the way of Ph.D. candidates—and not all of those barriers involve research and writing. Another pernicious barrier is student debt, something professors rarely think about.

Graduate students walk a hard line, so it\’s appropriate that they not enter a dissertation defense with a fear of failure. The Harvard English professor Lawrence Buell proclaimed a widely held sentiment when he wrote to me in an e-mail that \”nobody\’s handlers will let them walk into this event and fail.\”

Indeed, I know of no adviser worthy of the name who would permit a student to schedule a dissertation defense when there\’s such a risk. Stories of failed defenses do circulate, however. They typically conclude with students having to rewrite portions of their dissertations and resubmit them. The tellers all agree that these occurrences are rare: They are mistakes, not standard operating procedure.

Still, problems do arise. The most frequent kind crops up when faculty members turn the defense into a battleground for their own internecine quarrels, and the student gets caught in the crossfire. Committee members may disagree about the value of a topic covered in a dissertation, or they may simply dislike one another. But it\’s their job to negotiate collegial conduct beforehand and keep their squabbling from interfering with the student\’s defense.

When dueling professors use their questions during a defense to score points against one another, the best course of action for the student is to stay cool. Remember that it\’s not about you. Whatever their petty argument, you\’re going to leave with a degree in hand. Also remember one of the commandments of job interviewing: Hostile questions handled with grace make the questioner look bad.

Stephen North, in Refiguring the Ph.D. in English Studies, describes the dissertation defense as a \”magisterial emblem.\” North pictures an aspirant who \”faces any and all challengers\” to defend a \”thesis he has affixed to some figurative door of the cathedral of learning.\” I like that image for its extravagance, which captures the ornamental import of the moment. The defense, North says, is \”the ultimate rite of passage.\”

But the ritual shouldn\’t overshadow the practical value of the thing. The defense gives the committee a chance to reflect together on the candidate\’s finished product—and to view it as a steppingstone to whatever comes next. That might be publication. (Should the dissertation lead to articles, a book-length manuscript, perhaps a scholarly Web site?) Or if the student has already begun publishing, as is often the case, the discussion might center on how the dissertation can point the way to future work in the field. The advice given by committee members might conflict, but that needn\’t pose a problem. It just provides more ideas to sort through later on.

The defense has yet another important purpose: It confers a formal welcome to the community. It wasn\’t all that long ago that academe had many more trappings than it does now. Professors wore their gowns to lecture, for example. I have no love of any such pomp, but my years in the business have taught me to value certain formalities.

Not all of my Ph.D. students have become professors, but the defense gives them full membership in the intellectual world that they\’ve already worked in—and belonged to—for years. They\’ve earned that distinction, and they deserve to receive it in person.

One more thing: The defense also allows the faculty to say thank you. Working with graduate students on their dissertations provides us with interesting and challenging work. We don\’t just let them share—they also let us. We should think about that privilege more often than we do.

Dissertation work can be solitary. Even in a science lab, your dissertation project is your own. The defense gives not only public space but also communal attention to a project that usually deserves more than simply to have its title listed in a commencement program.

I recently learned that my old department has reinstituted the dissertation defense, but with an asterisk. It\’s now called a \”conference,\” not a defense, because the student is technically not defending the thesis, which has been accepted ahead of time.

Instead, the conference is designed to give the student the benefits that I\’ve described from consulting with the committee, including the ritual congratulations from those present. News of that change delighted me as an alumnus, and as a columnist who would prefer not to attack graduate-school practices all the time. We do some things very well indeed, and the dissertation defense is one of them.

Author Bio: Leonard Cassuto, a professor of English at Fordham University, writes regularly about graduate education in this space. He welcomes comments, suggestions, and stories at [email protected].