Should we discourage would-be PhDs?

I never learned calculus.  I didn't understand basic concepts in physics until my twenties, when my partner, a philosopher of science, had the grace and patience to start explaining them to me.  (This side of my education continues: just the other day, I got a refresher course in the physics of sound over a tasty dinner at Simpson Wong's new Chinese fusion place.)  My ignorance is mostly my fault -- I've happily exercised my capacity of rational choice and concentrated on things I was good at and found pleasure doing -- and partly the result of baneful external influence.  By the time I was twelve, I'd been convinced by a few small-minded teachers that girls weren't really suited to math (this in a girls' school!-- with terrific teachers of English, religious studies, and history, I might add).  My high school physics teacher, now retired, was perfectly friendly to me on a one-to-one basis, but I have clear memories of his boasting that his AP Physics class was all boys -- proof, to him, that it was a tough and serious class.
Partly thanks to this experience, I don't have a blanket policy of discouraging students from any course of action.  Who am I to tamp down another person's desire for knowledge?  Who am I to say whether a student who comes late to the study of ancient history or Greek won't be the next Peter Brown or Froma Zeitlin -- or Michel Foucault, for that matter?   This is what Peter Abelard would have called the sic, the "yes."
Now for the non.  There are very few jobs out there.
Here's another non -- to me, the most important.  I would ask any student seeking employment in an industry or government agency where questions of ethics immediately arise, say, the tobacco industry and the CIA, whether she or he has thought about the ethical implications of doing such work, if parents or friends are the driving forces in the decision, whether other desires or interests are being sacrificed and for what reason.  I no longer give academia a free pass.  I'll ask any student considering pursuing a PhD to consider what she or he is getting into, institutionally and ethically.  The university has a lot of self-examination to do, as an institution, and I think that we need to focus intently on how we operate and how we govern ourselves before we throw more students into the churn.
Here are some of the questions faculty need to ask themselves about the institutions that employ them, how they're run, and where their resources are going:

• What work am I being paid to do?  Does the institution operate in such a way that I can do that work?  For example, if I am being paid to do research and teach with some service (a typical answer at a research university), how much time am I spending on service?  
• Do I have sufficient administrative support?  Am I losing time I would have spent on teaching and research to filling out forms, assessment exercises, reimbursements, xeroxing, maintaining websites, managing student files, and other jobs that may have been done by administrators or admin aides in the past?  (Worth talking to older colleagues to get a sense of history on this one.) 
• Is work on departmental and university-level committees distributed transparently and fairly?  Who in the department and in the dean's office keeps track of this?  If I want to raise a question about my assignments, may I do so without raising a firestorm?  If a colleague wiggles out of work, who manages the problem?  May I complain without being a snitch?  In sum, do management procedures exist and does everyone know about them? 
• Another management/accountability question.  When someone's teaching is not up to standard, what happens?  Is there a process in place by which legitimate student complaints can be distinguished from whining about low grades or a stern personality?  Is this run by faculty or by deans who have not stepped into a classroom in years? 
• Does the university reward teaching to a degree that professors are encouraged to improve?  
• A few meta-management questions.  Who runs the place?  Aside from the president and (in many places) the provost, how many vice-presidents, associate provosts, vice-provosts, special assistants to the president/provost/vice-presidents, and so on are on the payroll?  What's the size of their support staffs?
• Is the administration dominated by people with PhDs in "higher ed administration" or professional fields like law or engineering?  If so, how do they value teaching and research in the non-professional parts of the academy, which we used to think of as the core -- namely, the humanities, arts, and sciences?    
• What work does the institution reward faculty for?  How does this work affect or connect to the students who are paying the bulk of our salaries?  (True at most institutions, barring the super-endowed places like Princeton, at 17 billion and counting, and Harvard, an eye-popping 32 billion last year.)  
• What procedures are in place to change the university's priorities or to establish big projects, and what role do faculty play?  

I don't think I'll succeed in turning away students from academia in large numbers, and part of me doesn't want to do that anyway.  My aim is rather to get them in the habit of asking these questions in the first place.
Academics are great critical thinkers, but as I'm far from the first to note, our critical faculties wither when we turn them on ourselves.