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    I have noticed that my old question How many mathematicians are there has been closed.
    Here is why I think this was a bad move.

    To the question "how many mathematicians are there" , anybody with a strictly positive IQ can smugly retort "Define mathematician !" and go away convinced that he has dealt the question a death-blow.
    The point is exactly that the question asks for some well defined proxy for being a mathematician and then deduce some number for that altered definition.
    I was exhilarated to discover (more than two years ago) that four brilliant answers did exactly that and the amazing conclusion is that all these answers give the same order of magnitude: there are about 100000 mathematicians on earth.

    What are you saying? You disagree, now that I made you aware of that result? Too late, you can no longer give your counter-arguments as an answer nor as a comment because five users (on a site with more than 18500 registered users, among whom are at least four Fields medalists) on this site have decided that it is now forbidden to discuss the question any further.

    I would like to add that I don't see how a mathematician could not be interested in those numbers at a time when positions are not particularly easy to get.
    And who else but MathOverflowers will give you the answer?

    Finally and more generally I would like to emphasize that some "soft" questions should be more welcome than the hard, tough, technical ones, which some macho users are so eager to publicize as the only ones they will tolerate. Here is why:

    I think that more than half of the 32000 questions here could be answered by just Pierre Deligne , Ofer Gabber and Terence Tao if they so wished and had the time: my point is that there is no lack of expertise in the world, but I'm not sure that even these luminaries could answer my question as well as our community taken together: a manifestation of the wisdom of crowds
    And this is why soft but unmistakenly mathematical questions should only be closed with the utmost care.
    Moreover the huge number of users due to the success of our site makes it preposterous that just five people with no special legitimacy other than having passed the low barrier of 3000 "reputation" points can prevent all other users to interact with a question.
    (I know there are constraints due to the software but I am sure that any clear policy adopted by users on closing questions can be implemented just by being stated: this is a civilized site!)


    I agree that it would be good to leave the question open. I found the various answers interesting but far from definitive, and I can imagine some better answers being given.

    A common pattern on MO is that an old, popular soft question with very many answers resurfaces after a long hibernation and is quickly closed. Perhaps the those who voted to close had this pattern in mind. But I don't think the "How many mathematicians?" question fits this pattern since it had relatively few answers and could benefit from a few additional, better answers.

    • CommentAuthorbsteinberg
    • CommentTimeAug 20th 2012
    I often vote to close as no longer relevant old popular soft questions with over 40 answers. This is because the new answers tend to be repeats, have \leq 0 votes, etc... They dilute the visibility of the answers to the old questions, thereby making the question less useful. The question under discussion is clearly not in this category and I can't see any particular reason to close it since it doesn't seem like it will attract poorly thought out answers at this point. So I have cast a vote to reopen.
    • CommentAuthorquid
    • CommentTimeAug 20th 2012

    Since so far no one (other) of the people that voted to close commented, I feel some obligation to say something in particular since some details so far got a bit blurred and there is even some factual misinformation around, yet will try to keep it essentially 'facts only' (in the way I perceive them), as I promised (myself) to essentially stay out of such discussion.

    I woted to close this question (I was neither the first nor the last to vote, most likely 2nd or 3rd). Here is why:

    1. The questio became reactivated by an answer that was at the borderline between massively off-topic and spam (now deleted); it was if memory serves well some sort of request (not sure whether it was serious or ironic, due to the way high-school teachers are exclude from being mathematicians in the question, or purely fictional) of some high-school(?) teacher asking how to improve in maths. (So this question did just attract a very low quality answer, cf. bsteinberg comment).

    2. Contrary to what is claimed by OP, the question did not get four answers more than two years ago, but it did get three essentially right away in Nov 2009 (so more than two years ago), yet than an additional fourth one only in July 2011. And, this final one seems to me, based on comments, votes and my own judgement, considerable worse than the earlier ones; it got an estimate for US math PhD totally wrong, as pointed out by comments. (So, I observed a steep decline in the quality of answers, cf again bsteinberg comment.)

    3. The question has an accepted answer (unusual for CW!). To me this means OP got a completely satisfactory answer and even might not be interested anymore. The latter seems even more plausible as there is no sign of OP stilll being interested/paying attention to the question; via following up on comments or alike. In particular, a specific request for clarification (comment by Martin Jan 2011) received no answer by OP or anyone else. And, this while a new answer was even added afterwards (also no activity by OP related to it, while otherwise quite active commenting); so it is not just one comment that one might have missed.

    For all these reasons, I saw simply no reasons to keep this open. But I have no problem if it stays open if some people still care; I would even have voted to reopen myself if I had seen the request in time.

    One personal comment: Not sure if the name-calling was necessary. In particular, 'macho users' IMO is really a poor choice of words.

    • CommentAuthorYemon Choi
    • CommentTimeAug 20th 2012

    I would like to add that I don't see how a mathematician could not be interested in those numbers at a time when positions are not particularly easy to get. And who else but MathOverflowers will give you the answer?

    Speaking as someone who took two postdocs and a change of country to get a potentially permanent position, those numbers mean nothing to me - what would have mattered more are far more localized concerns, both country-specific and domain-specific. As for answers: well, it is not clear to me that the ones to date on that post are convincing. (Which of course supports Georges's contention that the question should stay open.)

    As for PhD=mathematician... can of worms there...

    I tend to be leery of questions that can easily attract bad answers. If I did vote to close that one (I remember voting on a few questions that had been bumped, usually due to new users leaving "answers" of the form "hello can you help me") then I apologize for any perceived slight.

    • CommentAuthorYemon Choi
    • CommentTimeAug 20th 2012

    As a side remark: IMHO, the wisdom of crowds can be well sampled by going into the Bigg Market on a Saturday night, or reading the comments left on the Guardian's Comment is Free blog/site/jungle.

    Let a hundred flowers blossom - especially if they are MathOver-Flowers.
    • CommentAuthorbsteinberg
    • CommentTimeAug 20th 2012
    @quid. I had not seen the deleted answer. I think still it is on to leave it open if the OP wishes. I worry more when there are > 20 answers.
    • CommentAuthorMariano
    • CommentTimeAug 20th 2012

    In a related note: I have just cast the final vote to close on my own question about proofs without words.

    Lately, my efforts to keep it... hm... as great as it started have not been enough.

    • CommentAuthorWill Jagy
    • CommentTimeAug 20th 2012
    And yet, Mariano, with every word, your own greatness flows forth.

    Bravo, Mariano!


    First of all many thanks to the users who reopened the question in the astonishlingly short period of a few minutes.
    Actually the closing of this question was essentially an opportunity to make a case for soft questions.
    I wanted to argue with a specific example at hand that contrary to a widely held point of view, it is easy to get answers to hard technical questions by asking the right specialists. The only obstacle is the self-restraint that a decent mathematician feels toward imposing oneself on a specific colleague. MathOverflow is an ideal remedy: people will answer if they have the time or are in the mood and we can thus ask away without scruples.
    The paradox is that softer questions cannot necessary be answered by these awesome colleagues and that there is no alternative to asking on MathOverflow, hoping that a few among the thousands of users have some information and/or out-of-the box idea as an answer. It was probably a mistake to mix up in this thread the specific question "How many mathematicians are there ?" with these general considerations, on which I would however still like to have our community's opinion .

    • CommentAuthorHenry Cohn
    • CommentTimeAug 21st 2012

    I'm not an enemy of soft questions overall, but I don't agree with the argument that they are particularly hard to get answers to. For example, for how many mathematicians there are, 100k is clearly the right order of magnitude (unless you have an unusually strict or loose definition of "mathematician"). I'd bet you'd converge to an answer like this by asking people at any departmental tea, but anything much more precise would require pinning down criteria for being a mathematician.

    • CommentAuthorsuvrit
    • CommentTimeAug 21st 2012

    Dear Georges, it seems that you took my comment as an affront? It was not meant that way: all I meant was that back in the day, it seems, very soft-questions were not only more tolerated, but fairly well received. These days, any question as soft as the one under fire here, will probably succumb to rapid closure, and perhaps pointers to the MO Faq. As an anecdote: when my MO questions were less mature, I once asked a question "which math problem has witnessed the largest number of different proofs" --- this question rapidly evoked a vehement closure response from the community, and I just deleted the question; now-a-days I wouldn't dare asking such a soft question!

    Moreover the huge number of users due to the success of our site makes it preposterous that just five people with no special legitimacy other than having passed the low barrier of 3000 "reputation" points can prevent all other users to interact with a question.

    I wouldn't be opposed if this limit were raised to 10K or 100K, so that only the "highly legitimate" people may vote. But then I guess it is equally preposterous to accept "up votes" from other "un-informed" users with just a paltry 15 reputations points? But then, aren't these the agreed-upon rules of the site? They could be changed if the community decides to. Weighted majority, while not perfect, might perhaps offer a more satisfactory solution to give "weighted legitimacy"?


    @ suvrit, thanks for your explanations and apologies for the misunderstanding. I suppose I did not express myself clearly: I don't believe in the least that there should be a reputation threshold for closing questions , but on the contrary that no five people, whoever they are, should be able to prevent the thousands of other users to decide for themselves how they want to react to a question (for example by ignoring it).


    I wonder what the SE2 rules are on closure? The same as in MO1 now?

    Joseph, yes, you need 3000 points to vote to close, and 5 votes are needed to close. It's all in the faq.

    @Gerry: Thanks.

    • CommentAuthorMariano
    • CommentTimeMay 14th 2013 edited

    Sadly, the «Awfully sophisticated proofs» question should probably also be closed...

    I really wish people were more selective in what they add to list questions. I enjoyed that thread a lot.