I think PhD is the first time, mostly, when a person does original new work and in this process they gain the skills to do research. So, I was wondering why do people do postdoc(s) when they already have those research capabilities which they can practice even being a Professor or in Industries. Is there something else left to be learned?

  • 8
    You missed the obvious point - enjoying academic freedom and following a topic that you are interested in. If you go into industry, you will find that you are far more constrained in what you can do. Academia, especially if you can bring in funding, will offer you the ability to do what you want to do.
    – DetlevCM
    Feb 10 '17 at 18:19
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    Because, in a nutshell, you are talking about research. But that’s not what professors are mostly doing. Feb 10 '17 at 18:24
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    Not everyone wants to teach (or is competent to do so), which is a basic part of being a professor.
    – jamesqf
    Feb 10 '17 at 20:17
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    Number of PhDs > Number of Professors. So you insert another intermediate step where eventually people will drop out, not necessary due to skill but rather due to the lack of motivation to complete this additional step.
    – image357
    Feb 10 '17 at 21:09
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    @SalvadorDali If you work in a research institute, it may be that anything you want to do has to be approved by the "higher ups". I know of one person who has left a well paying research institute for a university (where he is now an "associate professor") because it will give him more academic freedom. And if people go into industry, besides not neccessarily being eligible for many grants, they will not be able to decide what they research without their managers approval - even if they have funding for it. That's where academia offers freedom.
    – DetlevCM
    Feb 11 '17 at 10:47

Because the requirements for the majority of professorships are such that very few people can be considered serious applicants right out of their PhD.

Also, the number of PhD holders looking for a professorship far exceeds the number of available positions which creates a "backlog".

The two are obviously correlated since the higher the demand to offer ratio, the pickier the institutions can be.

So even in the case where people developed the necessary skills to conduct professor-level research and teaching during their PhD (which should not be underestimated, that level usually requires more experience than what a typical PhD can give), they usually need to spend some years conducting independent or less closely-mentored research along with students mentoring and teaching as a postdoc until they can secure a position.

Note that the majority of postdoc researchers never get a faculty position.

  • 3
    @ankit the relationship is different. There usually is mentoring person, often someone who provides the funding and scientific guidance, but typically you should be much more on your own.
    – Cape Code
    Feb 10 '17 at 16:10
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    And worth noting, this is a trend that should show no signs of slowing down. It will be harder and harder to land such position, as more and more people get their degrees.
    – Mindwin
    Feb 10 '17 at 16:43
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    @ClassicEndingMusic in research, "the Ivy League" means absolutely nothing: What is important is which people and departments you worked with/under and how respected they are in your field. Even then, just working with great people does not guarantee that you yourself are great. Feb 11 '17 at 19:02
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    @ClassicEndingMusic it's basically the same thing. Of course prestige plays in your favor and it means you most likely have been confronted with stricter standards, better guidance, etc. but that's just on average. It doesn't mean you're automatically professor material.
    – Cape Code
    Feb 11 '17 at 19:20
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    @ClassicEndingMusic Duke is not in the Ivy League athletic conference; they are a member of the ACC. (In other news, it's a good idea to not get so hung up on which athletic conference a school is a member of.)
    – Mad Jack
    Feb 11 '17 at 20:09

In the sciences, the simple answer is the production of Ph.D.s far exceeds the number of faculty positions (see here). In the days of yore (1950's - 1970's), academia was expanding and new Ph.D.s could more easily land faculty positions.

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I believe the postdoc position was invented as a natural way to take advantage of the oversupply. What professor wouldn't want to have a seasoned academic researcher who has already published on the team, for a low rate? It's true there are more skills newly-minted Ph.D.'s need to develop, as noted in the other answers. But that was the whole point of junior faculty positions.

The more recent advent of postdoc positions in the humanities is discussed in this article.

  • Kudos for the factual answer. The oversupply of PhD is a long-standing issue.
    – Nemo
    Feb 11 '17 at 9:39
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    @Pete: Not sure I agree with this. Niels Bohr was a postdoc of Ernest Rutherford in the 1920s, and Heisenberg was a postdoc of Niels Bohr, at a time when there was hardly an oversupply of PhDs. (These are far from the only examples). Postdocs often had "research associate" positions, a different name for the same beast although the rules were probably different. It seems broadening one's research horizons was the major motivations. I do agree about the idea of oversupply in the more recent times.
    – user67075
    Feb 12 '17 at 2:36
  • @ZeroTheHero Excellent examples. One thing I would like to look at are the CV's of newly-hired (junior) faculty over the 20th century.
    – Pete
    Feb 12 '17 at 2:54
  • What....! where did the excessive PhDs go! I know that competition is everywhere, but this is crazy... Feb 13 '17 at 10:39
  • @ZeroTheHero: I wasn't able to confirm your claim that "Niels Bohr was a postdoc of Ernest Rutherford in the 1920s": see e.g. en.wikipedia.org/wiki/Niels_Bohr#Early_years. Rutherford offered Bohr a reader position (this is not a postdoc) in 1914 and Bohr accepted, but could not take it because of WWI. By the 1920's, Bohr was the director of his own institute, later named the Niels Bohr Institute. Heisenberg visited Bohr for one academic year while he was a Privatdozent...a German position that one can argue is functionally more similar to a postdoc than a professorship. Feb 13 '17 at 14:31

The answers by Cape Code and Paraquat cover some central reasons someone would pursue a postdoc, but there are some other reasons--as well as reasons a school might rightfully find that post-docs are better prepared to be research professors.

Diversification of research experience. If your only training in independent research is your PhD advisor's research, it can be challenging to strike out in a new area. Most PhDs don't want to be a copycat of their advisor's research: it leads to interpersonal tensions, and you're more likely to get scooped when you're starting. Taking your expertise to a new field in your postdoc can be valuable in:

  • Broadening the research techniques you're familiar with (e.g. specific instrumentation, models, or lab measurements)
  • Broadening your field of expertise
  • Developing your own core research questions, which are not copies or derivatives of your advisor's
  • Contributing your specialty to a new field to make an impact with a different perspective

Learning How To Manage Researchers When you're a graduate student, you're in the trenches doing the actual work. When you're a professor, you're managing a group of people who are doing the work. Managing well is very tricky. Are you going to micro-manage them? This might get the work done faster, but then you're preventing your students from developing independence, because you tell them exactly what to do at each step. Also, you might be missing out on important research questions that they are asking and interested in pursuing. Are you going to be very hands-off? They might spin their wheels unproductively, and even quit the program after you've spend the time and money training them. How do you find a balance? Do you think happy and satisfied and curious graduate students do better work? How do you make sure they are happy and satisfied and curious while still getting work done and papers written? Effective group management is a set of skills that you are not typically taught as a graduate student. However postdocs often mentor graduate students and could even manage a small research focus within the group, and this can build these management abilities with guidance from the PI.

Experience Writing Grants. Sometimes graduate students write grants or help a professor write grants, but not terribly often. A postdoc can be a good opportunity to co-write a grant proposal with your PI, to give you experience in grant writing. Being able to fund your research as a professor is integral, and how to write grants effectively is a skill that we don't typically teach graduate students.

Becoming more of a presence in your field. To be a successful professor you need to: get funding, publish papers (i.e.: get papers through the peer review process), maybe find collaborators, be invited to give talks, etc. That all comes a bit easier if people in your field know who you are. There's a lot of work to do to set up your lab and recruit graduate student as a new professor, and you'll also have departmental obligations (like committees to serve on), and teaching requirements. If you can start getting your name out there as a post-doc by going to lots of workshops and conferences, it's a little less pressure on you when you're trying to get all your other ducks lined up for tenure.

  • 1
    +1 because this is the "canonical" answer that I hear whenever this debate comes up in-person. However, I think it's a bit of a "theoretical reason" of why PhD should do postdocs instead of why they do them. Furthermore, I think a portion of people this answer represents expected to do a post-doc after their PhD (explained by the other answers), and therefore intentionally defer gaining these skills and experiences until their post-doc. Feb 10 '17 at 17:22

The following description is valid at least in Germany as I experienced it in the natural sciences. I am not sure whether it is also the case in other countries.

In Germany, you have to do teaching when you have a professorship at a University. There are a few exceptions. Additionally, you are expected to lead a working group, attend faculty meetings, supervise PhD students, grade Bachelor's and Master's theses, obtain third-party funding and probably some minor things I forgot. It is a secure position and you earn good money but there is not much time left to do research .

As PostDoc (but also as senior researcher with permanent contract) you also have some of these responsibilities - but not all and often you can choose more flexible what to do. The important aspect is that you do have more time available for doing research (compared to being a professor).

Moreover in the past, a "Prof." (and also a "Dr.") had a very high reputation in the society. It changed in the previous two to three decades. You have to deals with students -- particularly in their first year -- (and in recent years their parents!!!), who claiming for good grades and a higher quality of the lectures. The latter is actually a positive aspect. However, in my experience people are often not adapting to the university-kind of learning and expected highschool lessons instead of lectures (but that's another discussion).

Summarizing, a professorship a German universities is better paid and a more secure job than a PostDoc position but it also brings a considerable amounts of responsibilities taking a lot of time, which you loose for your research).

  • 1
    Well, Austria and germany are usually very similar in these things and in Austria you won't get a professorship unless you did postdoctoral research before (and usually you should have been abroad too). So most postdocs who want to stay in academia are actually in the state between PhD and Prof.
    – user64845
    Feb 10 '17 at 21:29
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    This answer applies to the US as well, although certainly the German steep pyramidal model is an extreme case. In general, the postdoc period is a bit of a honeymoon, a temporary reprieve from many responsibilities that take can distract one from research endeavors. Feb 11 '17 at 2:24
  • Maybe I exaggerated a bit. A professorship is nearly non-terminable (except if you do a crime). Therefore, you can also lean back and do nothing after you got it. But in my experience the latter kind are the minority. || There are also several permanent positions for scientists at non-university research institutions. These are good alternatives to professorships. Feb 11 '17 at 22:18
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    I think the situation is very similar in the US. Also I think that it's possible the OP may not have been thinking about the distinction between "employed teaching at a university" and "professor." While students will call anyone in front of a classroom a "professor," to technically achieve this title requires much much more. Most people just finishing a PhD are not even able to obtain a position where research is part of the job, so a postdoc is often the only option where one would have the time to do research.
    – j0equ1nn
    Feb 12 '17 at 15:21

In many countries, you need a good publication record to be considered for a permanent position, and the only way you can get a good publication record is though postdoc work. There are also far more applicants than there are permanent positions (in all of the places I have worked, anyway); a postdoc once told me of a job interview he had in Oxford, where he met two senior professors applying for a junior permanent position; needless to say, they weren't too pleased to see each other. I don't know what it's like in the humanities, but for some reason, many jobs, both permanent and contracted, prefer applicants who have had some degree of mobility, i.e. have done research abroad, and a postdoc is a good way to do this, while building an international network.


Positions at research universities receive hundreds of applications. Applications from fresh PhD's are difficult to evaluate (and thus have almost no chance) because it is usually impossible to know which of the ideas in the PhD thesis came from the student, and which came from the advisor.


To understand the question it is important to understand the role of postdoc in an academic career. How I see it:

  • PhD student

A training to be a researcher. May end up as a researcher outside academia. Even some business manager positions require MBA or PhD.

  • PostDoc

A full time researcher within academia.

  • Tenure Track (Associate etc.)

A gradual change from a full time researcher to a full time manager.

  • Proferssor

The managers of the university.

PostDoc is a way to keep the researchers within academia. They conduct the best research because they are no longer students, but they have none of the managerial responsibilities of a professor. As always, things may vary between every parameter you can name (time, place, field, attitude...).

  • In some institutions there is also the matter of distributions of instructional duties.
    – Weckar E.
    Feb 13 '17 at 10:19
  • I had to off-load some of my management functions by hiring a "program manager" who helped deal with my many research grant deliverable artifacts (such as drafting the monthly and quarterly progress reports for a dozen different grants) so that I had sufficient time to mentor and manage my Ph.D. students and post-docs and visiting post-doc scholars, and to contribute my own work to the research. May 19 '17 at 18:21

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