What a PhD thesis is really about… really!

I was recently pointed to a blog post about doing a PhD. It had lots of interesting advice, mainly along the lines of ‘if you are finding it difficult, don’t worry, that probably means you’re doing it right.’ True, and good advice to keep in mind for PhD researchers who might be feeling lost in the wilderness. But it reminded me that I’d recently given a talk about PhD research, based on experience I have either examining or supervising dozens of theses, and some of the main points that I made are worth sharing. And I think they are applicable to research-based PhDs across lots of different disciplines.

First off, lets think of a few things that a PhD thesis is not supposed to be;


  • A thesis isn’t easy

See the blog I mentioned above. Easy research may still be publishable, but its not going to make a thesis. If you’re finding it easy, you’re probably missing the point.

  • A thesis is not only what you already know

I’ve known researchers unwilling to learn a bit of new maths, or learn what’s going on under the hood in the software they use. Expect the research to lead you out of your comfort zone.

  • A thesis isn’t just something you do to get a phd

It’s not simply a box that needs to be checked off so that you can get ‘Doctor’ next to your name.

  • A thesis isn’t obvious

If you and most others can predict the outcome in advance based on common sense, then why do it?

  • A thesis isn’t just several years of hard work

It may take years of hard work to achieve, but that’s not the point. You don’t get a PhD just for time and effort.

  • A thesis isn’t about building a system

that’s challenging and technical, and may be a byproduct of the research, but its not the research result.

  • A thesis isn’t a lot of little achievements

I’ve seen theses that read a bit like ‘I did this little interesting thing, then this other one, then another one…’ That doesn’t look good. If no one contribution is strong enough to be a thesis, then just putting them all into one document still isn’t a strong contribution. Note that in some cases, you can do a ‘thesis by publication’, which is a collection of papers, usually with an introduction and some wrapper information. But in which case it should still tie together with an overall contribution.

So with that in mind, lets now think about what a thesis is, with a few highlighted aspects that are often neglected.


  • A thesis advances knowledge

That’s the key. Some new understanding, new insights, backed up by evidence and critical thinking. But this also suggests that it needs to actually be an advance, so you really need to know the prior art. How much reading of the literature one should do is a different question, and depends on the topic, the field, and the researcher. But in my experience, researchers generally don’t explore the literature deep enough. One thing is for sure though; if the researcher ever makes the claim that no one has done this before, they better have the evidence to back that up.

  • A thesis is an argument

The word ‘thesis’ comes from Greek, and means an argument in the sense of putting forth a position. That means that there needs to be some element of controversy in the topic, and the thesis provides strong evidence supporting a particular position. That is, someone knowledgeable in the field could read the abstract and think, ‘no, I don’t believe it,’ but then change his or her mind after reading the whole thesis.

  • A thesis tells a story

People tend to forget that it’s a book. Its meant to be read, and in some sense, enjoyed. So the researcher should think about the reader. I don’t mean it should be silly or salacious, but it should be engaging, and the researcher should always consider whether they (or at least some people in the field) would want to read what they’d written.