I recently received an application for a PhD position from someone who is already working as a postdoctoral associate. The difference in fields is not particularly large—I work in chemical engineering and materials science, while the applicant originally is coming from computational chemistry.

So the obvious question is, why would someone want to pursue a second doctoral degree when they already have one in a related field, and why would I, as a potential advisor, want to consider someone interested in doing this? (For instance, it seems obvious that the person wouldn't likely need as much training as a novice, but there would also be the challenge of trying to find such a person gainful employment afterwards.)

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    Perhaps by pursuing another doctoral degree the person will get a study leave and a fully-paid scholarship with stipend? – Joel Reyes Noche Dec 25 '12 at 23:48
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    And some people just collect degrees ... – 410 gone Dec 26 '12 at 0:08
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    @JoelReyesNoche: Except the person is already likely making more money as a postdoc than they would get, plus the additional career delay. – aeismail Dec 26 '12 at 0:37
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    One of the best lecturers I've had did this. He did an applied maths PhD, went into industry as a statistician, and then went to get an econometrics PhD. He did this to switch fully into econometrics academic research which would've been a bit difficult with just an applied maths phd and no econometrics research experience. However he was getting paid full salary while he was doing it so it's not the same as a normal PhD student. – Jase Dec 26 '12 at 3:12
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    I know of a case where someone shifted from a tenure track job in area X to an MS in area Y, because area X didn't look like a viable career option compared to Y. – Suresh Dec 26 '12 at 3:57

I've seen two reasons for this. The more worrisome reason is the one mentioned by EnergyNumbers in the comments, namely that some people just collect degrees. In particular, they may feel having two Ph.D.s would look exceptionally impressive, or they may be unable to settle on a specialization, or they may feel that getting another degree is somehow preferable to getting a job. These could be legitimate as personal desires, but they are counterproductive for a research career.

The other reason is to recover from a bad career start. Sometimes someone's grades keep them from getting into a good graduate program, or they face other constraints (geographical or financial) in their choice of programs, or they fail to connect well with their advisor. They may eventually get a Ph.D., but not under good circumstances, and a second Ph.D. might lead to a much better career. The difference between this case and the first case is that these students don't actually want a second Ph.D. as such. They regretfully feel they need one to achieve their career goals, but they wish it had been their first and only Ph.D.

Recovering from a bad start is a less worrisome reason to seek a second Ph.D., but of course the challenge is figuring out which students have moved beyond their past difficulties and which have not.

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    I would add that it might be someone taking the opportunity to go from a low tier school PhD to a high tier one. – Broklynite Dec 10 '15 at 10:40

You didn't mention what country you are in or the relative standing of the two universities & supervisors involved. Sometimes people apply for a second PhD because their first one is not sufficiently well respected to get at good job.

Another reason is because the candidate really is just enjoying that stage of life. In the USA, one can often stay a PhD student for years in a top institution, but in other countries there are hard time limits. I also know of several people who took multiple PhDs at top universities just because they finished the first one too young to take a chair yet (and one person who didn't let that bother him & took a chair at 18, getting his father an office nearby!)

The most important question though is whether you want this person as a student – will they finish? Do they know what they are getting in to? If they have a PhD, they are in some sense a peer, and certainly should have a reputation. I would spend more time than usual pursuing the references, possibly with phone calls, and I would certainly talk at length with the candidate about whether they would really finish writing up a second time. I would only take them with exceptionally strong references from others and a very good personal narrative about why they want and would complete a second degree.


I think its all about the jobs that the first PhD could not bring to them. I myself have a PhD from an Egyptian university, but it seems that nobody is willing to offer me a post-doc position because I don't have 10 journal papers with extremely large impact factor as a PhD student from an advanced country would have. Of course the conditions are very different between a university in Egypt and another one in the United States or Europe. That's why I will keep looking for another PhD from a very high ranked western university.

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    You don't need "10 journal papers with extremely large impact factor." You do need strong letters of recommendation and good communication skills. Some record of publication in respected journals (not exclusively "high impact") is also helpful. I had two papers in a "mid-impact" journal published when I got my postdoc, and very few grad students have more than a handful of papers out. – aeismail Mar 3 '14 at 17:10
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    well i still think it has something to do with "where did you got your PhD from?" it must be a high ranked university... however, i will try to follow your advice with post doc application, if not i will continue looking for another PhD in europe, america, or australia – Khaled Mar 3 '14 at 22:07
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    I think the question people hiring postdocs are asking is "Who do I know that can vouch for this person?" Nobody wants to take a risk on hiring a weak candidate if they can avoid it. Having someone tell them the candidate is worth hiring goes a long way. Also, going for a second PhD is harder than you think: you'll need to give a very clear explanation for why you want a second PhD if it's in a field near the one you already have. – aeismail Mar 3 '14 at 23:20

there are many reasons doing another phd. I have done a phd in chemistry, (one year postdoc and 2 years as a researcher in R&D). and today, applying for another phd. I have more than 10 papers (each one with impact higher than 2). what makes me to think for another phd, is not job, it is knowledge. actually, I have a position as a lecturer, and have been offered a position fro assistant prof. however, I prefer to gain more experience and knowledge as I can. so I am applying for a position in interdisciplinary field (material chemistry). considering my experience in chemistry, I would be more successful in the future.

  • That doesn't necessarily make sense, though, as there are many ways to acquire knowledge other than going back and getting another PhD. In fact, part of a PhD is to teach you how to amass and sort vast amounts of knowledge, so a competent PhD-holder could segue from one field to another very closely related one without getting another PhD. – roseofjuly Jan 4 '16 at 21:32

I am from Africa. None of my degrees (Bachelors or Masters) were recognized in the UK, leaving me with no choice but to study for the same degrees again. Not sure if this applies to PhDs, but I can imagine a similar situation.

  • Cleaned the answer up a bit, removed commentary. Question, though: what do you mean "not recognized"? What were you trying to do with your masters degree? – eykanal Sep 11 '14 at 13:51

One of the reason why someone would like to do another PhD could be attaining a degree and knowledge is allied field as most of the current research now a days are focusing on multidisciplinary application based approached. This off course has to do with the field you are in and in this case mine being nano-biotechnology. As far as the OP's question is concerned the applicant had a PhD in chemistry and now he want to move towards computational chemistry. How I see this is that chemistry is quite focused and has set boundaries but if he manages to enter the field of computational chemistry his scope widens as computational chemistry is not only applicable in chemistry but also has scopes in modelling, biotechnology, protein chemistry nano chemistry and so on.

Also it could be a reason that from the previous PhD in chemistry the applicant only did basic research and now he is motivated to do application based research.

Other reason might be that he has less publication during his first PhD which he wants to improve with the second one.

And yes one very obvious reason could also be lack of postdoc position due to recession and reduced government research funding as most seen in Europe now a day. Where many research are applying for a second PhD due to the lack of postdoc position......as fully funded PhD position are more available than postdoc position....


First why a Postdoc would consider a second PhD:


Needless to say, how the existing system treats the Postdocs-Use them, as a cheap labor and throw them. In almost all of the occasions, it is the Professor/Supervisor who is benefitted. According to Nature article, vacancies in academia is available only for 15% of the Postdocs. In addition to this, comes the problem of Visa and Racism. In France, it is impossible for one to get a job (even in Industry) let alone be called for the interview, without perfect French and a "French" sounding First & Last Name. Yet, French institution lure students from developing countries with their fancy programs. In one of the article on the "invisible" racism in Canada, one even acknowledged that the system is skewed in favour of Canadians (they want the good jobs for Canadians), yet they beckon PhD's and postdocs, from all over the world. Then, say the education is not enough, forcing them to work as bartenders and taxi drivers. Nature (Journal) itself points to some postdocs to have taken up the job of a forklift. Personally, I know a postdoc ending up as a stay-at-home Dad...And in almost all cases, none even spares a moment to think about the future and families of their postdocs or help them acquire skillsets that could help them move to industries, in the worst case scenario. Neither, opportunities in entrepreneurship is supported (National Laboratories, for example). In fact, Canada actively discourages it.

So, the best reason I think a person would choose a second PhD is to survive and since, PhD is usually longer than a postdoc could hope to acquire skillsets that could be used in industry and subsequently find a job. Personally, I would urge you to consider the postdoc as you'd be helping him and also prevent another "idiotic" bright student from wasting his life in the name of academic/knowledge pursuits It is a beneficial proposition for you as well, as a postdoc would require less supervision and hence more publications could be achieved for lesser cost...!

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    Most of this "answer" is a complaint about the academic job market and postdocs in particular, that is unrelated to the question of doing a second PhD. Since (according to you) getting a job is all about having the right nationality, it's not clear why a second PhD would accomplish anything at all. – ff524 Dec 10 '15 at 4:15
  • First it is not a complaint. If at all, it is because the professors hide the truth. Even when having the right nationality is a requirement, as I mentioned earlier, it (PhD) would give the postdoc some time to add some skills for his future (1st line)... Anyway, the professor is going to gain more... what is the big deal..? – Anonymous Dec 10 '15 at 4:25

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