Every now and then, someone who is considering undertaking a PhD by thesis will seek my thoughts about doctoral supervisors. And while there are lots of things I might draw the enquirer’s attention to, my standard reply is that I reckon that you want to look for 3 things in a supervisor:

1. Someone who makes time for you, including responding to your calls/emails in a timely manner. There’s an element here too of the ‘pastoral’ reality in the supervisory relationship. A good supervisor knows, or at least acts as if they know, that they are working with a person and not just with ideas, and that most often that person experiences ‘the thesis’ as a mixed ride, and often with not a little stress, both internal and external. Some confidence that the supervisor is an aid – which includes some basic reliability on the communication front – and not a thorn in this journey is pretty important. (Side note: The 3-year thesis has some affinities with pregnancy, or so I’m led to believe. The first trimester is often about excitement and adjustment, and some weird conviction that this baby is going to be the best thing ever. Sometimes vomiting is involved too. The second trimester is like being in cruise control, and the baby sort of just hangs around while one starts to be a little more lax about the ‘no-alcohol’ rules and stuff. And the third trimester is something akin to ‘Let’s just get this baby out of here – enough is enough’.)
2. Someone who knows what a doctoral thesis looks like. Just because a person has one doesn’t guarantee that they know what one looks like, or how to go about authoring a decent one, or helping someone else to do so.
3. Someone – and this is perhaps the most important of the three – who asks the right kinds of questions. In other words, you’re not necessarily looking for someone who knows everything, or even a lot, about your subject of interest. But you are looking for someone who has a good nose for the general area and who can help you articulate the right kinds of questions. In PhDs – as in life – the right questions are always much more important, and much more interesting, than the answers.