Prospective PhD contacts potential supervisor but receives no answer after 2-3 emails, what to do?
To try to make a clear point: there is a range of opinions about how to respond to "cold calls" from people I don't know, etc. I myself find it easy to make a one-or-two-sentence response politely thanking an inquirer for their interest, but (if so...) that I "have no open positions in my group at this time" or whatever is suitable. For me, although I get a good number of these of various sorts, it takes less than 5 minutes a day, and I take the viewpoint that it is a good professional-social gesture to make that quick response (perhaps more worthwhile than yelling over the phone at phone-solicitors on old no-caller-id phones).
At the same time, at the other end, I know many people who take the viewpoint that sending them email no more obligates them to a response than do credit-card offers and other advertisements. And, indeed, given the ease with which we can mass-email, even with customizations, this is a fair, not unethical, not harsh reaction. Perhaps if my in-mails of this sort reached 10+ per day, I'd give up "trying to be polite", but my own current scale of "spam on behalf of earnest beginner in the business" is pretty low, so I can easily afford to be (superficially) "gracious" enough to respond.
In case people don't reply, I'm afraid you can't hold it against them, even while we admit that it would be great if they did respond, ... because there just isn't a general social principle that demands a response to all possible inquiries one may receive. Yes, it'd be nice, but it is simply not required.
I would say MOVE ON .. Some professors are full of students. They are not looking for new prospective students in the next year or so.
Therefore, the simple action to do is ignoring prospective students emails.
The best to do is to phone him/her if s/he didn't answer in 3 months after 2 or 3 emails. Try to meet him in conference and try to contact his/her current PhD students..
I am going to assume we're talking about a student who plans to apply to the PhD program that the faculty is affiliated with, but has not yet been admitted. (You didn't say explicitly, but reading between the lines, that is my assumption.)
If that's the case then the student should not expect a response and should not read anything into the lack of a response from the faculty member. Many faculty do not have time to respond personally to all enquiries from prospective applicants.
Please understand that some faculty receive dozens or hundreds of enquiries from prospective students. For example, my understanding is that many Indian or Chinese students are under the mistaken impression that they should contact faculty, or think it will help their case for admission somehow (not true; but they don't know, or have been given bad advice, so they write). Anyway, as a result, many faculty cannot possibly reply to all such contacts. I've even seen a few faculty post a FAQ on their web page which explains why they cannot respond to such inquiries from prospective PhD students who are interested in applying. In many cases, it is likely that few or none of those who contact the professor will be admitted, so professors may understandable decide that they cannot afford to to spend time responding to such contacts until after admission, in most cases.
To learn more about this, I can recommend some additional reading:
Advice for Prospective Research Students - a FAQ one professor posts, about how to contact professors
Writing to me - Advice from Female Science Professor (a pseudonymous professor/blogger) about how prospective grad students should write to her.
In general, anything from FSP is worth reading. Here are some additional posts of her that are relevant, and that may help to understand the professor's mindset:
- Mad Libs Gone Mad
- You Can Lead a Horse to Water
- What They Don't Tell You in the Non-Existent Training for this Job
If I have misunderstood the status of this student:
If the student has already been admitted into the PhD program where the faculty is affiliated with, but has not yet accepted the offer of admission, the lack of response probably indicates lack of interest or lack of time on the part of the faculty member. In this case, my advice would be to move on. As far as I can tell, though, this response would be a bit unusual: if the student has been admitted, it typically means that at least some quorum of faculty think highly of the student.
Finally, if the student is current enrolled in the faculty's PhD program, the student should go visit the faculty member in person. Faculty have office hours; go use them.