I have a Ph.D. in Theology. I’m happy I have the Ph.D., and it’s been useful to me both in my thinking and writing.

But would I have gone on for a Ph.D. knowing what I do now? Probably not.

Recently, my friend Dave Deavel published an op-ed in the Wall Street Journal titled “The Hardest Letter of Recommendation.” In it, he outlines the advice he gives to students who wish to apply to doctoral programs in the liberal arts in the hopes of becoming a professor. As he says, he will only agree to write a letter of recommendation for them if they accept his three conditions:

“First, you will not go to any program that wants to charge you tuition. Ideally, you will be offered some sort of assistantship so that you won’t have to look for other jobs to make money. Then you also can put on your CV that you’ve been a teaching or research assistant.

Second, you will go with the goal of being the best and most productive graduate student in your class. This means that you will have to start presenting at academic conferences and publishing articles as soon as possible. You will apply for fellowships and grants. You will finish your doctorate as quickly as you can and try to get some teaching experience.

And third, you will go understanding that even if you do all this, you still quite likely will not become a professor and will have to do something else for work.”

I agree with all three of Dave’s conditions, and have some of my own to add for those who want to become university professors:

1) Only apply to top-tier doctoral programs.

The academic job market is absolutely flooded with Ph.D.-holders looking for a very limited number of jobs, some of which get between 500-1,000 applicants. In that environment, who do you think schools are going to hire? Which applicant gives their school the most cachet? The guy with a Ph.D. from Harvard, Duke, or Notre Dame, or the guy who got his Ph.D. at a school that’s much lower in the U.S. News & World Report rankings? Even if you’re brilliant, and can hang with the best of them in terms of intellectual creativity, teaching ability, and publications, don’t kid yourself: pedigree still matters a great deal. If you can’t get into any of the top-tier doctoral programs, then you should start considering a different career.

2) Be comfortable with feeling displaced.

If you want to be a professor, you have to be willing to go wherever you can find a job. In your first year or two after receiving the Ph.D., you’ll most likely have to be content with chasing one-year visiting professorships in random locations. And then, if you happen to land a tenure-track position, know that it’s entirely possible that you’ll be in a part of the country you dislike, with a culture you dislike, and thousands of miles away from family. If you’re single, it’s a bit easier to deal with this kind of situation. If you’re married, it could test how much your spouse really loves you. And if you’re trying to raise children, it can make you and your spouse feel very alone. There can be much personal growth that comes from having a certain amount of abandonment about place, and learning to love those around you, whomever they happen to be. But just be prepared for it.

3) Develop a “tentmaker” profession.

St. Paul is known as a famous missionary, the author of several New Testament letters, and is sometimes referred to as the “intellectual founder” of Christianity. But in addition to these activities he was, as the Acts of the Apostles (18:3) tells us, a tentmaker. I recommend to future professors that they, like St. Paul, develop some practical trade or skill that they can fall back on should they decide that the university life is not for them. With declining enrollments and an increasingly insufferable and intolerant atmosphere on many college campuses, it’s likely that more professors will find themselves out of full-time academia in the near future. When that time comes, it’s best to hit the job market with a diversified resume. (H/T to Tom Curran for this point.)

4) If you’re a white male, think twice… maybe thrice.

Look, there’s a lot of talk about “white privilege” these days. I’m aware that 85 percent of full-time university professors are white, and 60 percent are white males. But, when looking for an academic job in the current market, many will tell you that being a white male is a handicap. It’s much easier to receive consideration for one of a limited number of available professorial positions if you’re a minority or a woman—or even better, both.

And for those who simply want to pursue a Ph.D. out of a sheer love of learning, my only piece of advice is this: Never, ever, go into debt for it.