What David MacKay taught me, and taught us all

The end, when it inevitably came, arrived much sooner than any of us – even David – had expected. After his diagnosis with terminal stomach cancer in July 2015, David MacKay, with characteristic mathematical clarity, sketched out his likely life expectancy on a whiteboard graph. As you can see in the image, he gave himself a 50:50 chance of surviving until January 2017, while “>2 years” was “v. unlikely”.
Probabilistic thinking came easily to David, as the many aficionados of his landmark textbook Information Theory, Inference and Learning Algorithms who are currently deluging Twitter with moving and heartfelt condolence messages will attest. However, sadly for David, for his family, for all of us, and indeed for the world, his remaining lifetime was very much at the left side of the S curve, and he died on the afternoon of 14 April 2016, just a week short of what would have been his 49th birthday.

David’s early death is desperately sad. David was not sentimental, but I simply can’t think of any other word. His children are so young – Torrin is 4 and Eriska only 1 – and now their father will not get to see them grow up, and his wonderful wife Ramesh is left alone. It seems so bitterly unfair. David wrote about all of this in his sparklingly honest and witty blog ‘Everything is Connected‘, and his post ‘What do you tell the children?‘, written on 13 September last year, dealt unsparingly – and humourously – with that uniquely awful dilemma. He knew he was running out of time by early April, and posted a farewell message of sorts: ‘Perhaps my last post – we’ll see‘, with this opening:

I noticed that the posts of a friend who died of cancer trickled away to a non-conclusion, and this seems an inevitable difficulty, that the final post won’t ever get writ. I’d like my posts to have an ending, so I’m going to make this my final one – maybe. While the doctors haven’t expressed an opinion, I think it’s possible I haven’t got long to go…

It wasn’t quite the last one, but subsequent posts – including a poignant but hilarious one about the hospital’s lack of “intelligent thermal environmental control” (which I really hope Addenbrookes and other hospital authorities will read and act on) are labelled Appendices “to my completed cancer story”. In the end, David got it just right, with his final Appendix 3 blogpost being a JustGiving site to raise money – in his memory, it now turns out – for the Arthur Rank Hospice Charity (please do donate – it is incredible how his fundraising target has already been quickly surpassed). I got a final text from him, just a day before he died, saying with characteristic straightforwardness “no visit thanks”.

David MacKay had more personal and professional integrity than anyone I have ever known – and yet somehow he managed to combine it with a warmth that underlay everything he did. (I was privileged to attend his celebratory Symposium in Cambridge just a month ago – I don’t think I have ever been in a scientific meeting with so much love in the room.) He wore his super-intelligence – people use the word ‘genius’ rarely these days, but I’ve heard it used for David a number of times – lightly, and always interacted with humility and an enduring sense of fun.

David had a strong moral compass and sense of justice – his work was fundamentally driven by a desire to make a difference, and to help solve real problems, even intractably huge problems like climate change. His massive contribution was bring numeracy to a debate obscured by mudslinging and ideologically-motivated rhetoric (both of which I’m as guilty of as anyone). It was characteristic of this desire to see real change that he accepted the immense challenge of taking on the role of Chief Scientific Advisor at the UK government’s Department of Energy and Climate Change, rather than staying in the ‘ivory tower’ of Cambridge, after the enormous success of his epochal book Sustainable Energy, without the hot air.

As you’ll see from the above lecture (perhaps my favourite, given in Oxford in 2014) David was most of all a quite simply brilliant teacher. It was not just that he was a gifted communicator – perhaps a rare thing for an expert on information theory and machine learning – but that he understood the need to help other people understand. This could take a lot of him time, which he always gave generously: on one occasion, on a Skype call, he spent an hour sketching graphs on a handy piece of cardboard in a doomed effort to impress on me the basics of Bayesian statistics (we were talking about p values being misused in scientific papers to inappropriately infer statistical significance). I still don’t understand Bayesian inference, but I trusted David to be right on that and a lot else besides more than I’ve ever trusted anyone before or will again.

That’s the problem with wise teachers like David MacKay. Normal people like me just want to be given the answer by someone super-smart that we trust, and thereby be told what to think. But David wouldn’t be drawn into handing out easy answers, whether as a university professor, a writer, a speaker or a government advisor. His whole effort was focused on giving people the tools and understanding so they could figure out the answers for themselves – even government ministers. And that is his legacy. Though the world has lost an incredible brain, and is the poorer for it, David left us everything we need to figure out for ourselves how to proceed with solving climate change – and other problems, however huge and complex they may appear. His formula is disarmingly simple: we have to get the numbers right, and think things through rationally from first principles. To borrow David’s best-known quote, we don’t have to be anti-this or pro-that: we just have to be “pro-arithmetic” and the rest will follow. I hope that we can do this, both to cherish David’s memory and because such an approach is after all the only way to get to the right answer.


Left to right: Maria Padget, Mark Lynas, David MacKay, Tom Lynas, Torrin MacKay, Rosa Lynas, Ramesh Ghiassi, Eriska MacKay – September 2015, taken by David on an automatic setting after several unsuccessful attempts!


  1. Clyde Davies

    A sad loss. Sounds like he was a remarkable man, as much for his humanity and spirit as his intellect. I’d have liked to have met him. Are there any YouTube recordings of him speaking?

    1. Luke
    2. John Stumbles

      A short early video introduces David’s characteristic human-scale measure of energy use: the light-bulb’s worth. A 40 watt bulb gets through 1 kilowatt-hour (one “unit” on your meter and bill) per day, and we UK citizens average 125 light-bulbs when you include the energy we use for transport, heating, the food we eat etc
      And here’s a video of an hour long presentation he gave at Harvard on Sustainable Energy Without The Hot AIr

    3. Clyde Davies

      Thank you. I watched the first talk, which was brilliant, and will provided me with much-needed ammunition the next time somebody starts slagging off nuclear power.
      The numbers-based approach cuts through the crap. I heartily recommend it.

  2. Clyde Davies

    Oh, and I should have says that was a lovely eulogy that speaks as much about the person doing the remembering, as the remembered.

    1. Mark Lynas (Post author)

      Thanks Clyde. I should have mentioned above how utterly grateful I am to have known David. Along with much else, he introduced me to the beauty of numbers!

    2. Clyde Davies

      I still grapple with the beauty of numbers!

    3. Jenny

      Mark, you did not need to say how grateful you are to have known David. It shone through every word you wrote. I have tears in my eyes from reading such moving words. Looking from the outside, his was a wonderful life, lived in a truly admirable way, and I am so grateful for the contribution he made to a subject that is a passion of mine. A wonderful mind with a rare gift of communicating his genius with humour and simplicity. It is heartbreaking to think of his children being deprived of their father, and his lovely wife of her companion.

      Thank you, not only for your eulogy, and for that wonderful photo of the human face of academia, but also for your hugely valued contribution to making climate change science available to the public.

  3. Bas Gresnigt

    Thank you for the excellent post about this very admirable man, David McKay!
    I love to read his writings. Admire the simplicity of his approaches.

  4. Bruce Heagerty

    Lovely eulogy, Mark. He was indeed a fascinating and humorous man and a great frisbee player! As we found out in Mach that day..

  5. Marek Bidwell

    Thank you for relating this sad news.

    We recently read and discussed ‘Sustainable Energy – Without the Hot Air’ at our bookclub and I can’t agree more with your comments about David’s clarity and ability to make us think for ourselves about the issues.

    I was also impressed by the fact that the text of the book is available to read for free on the internet. A rare gift in this commercial world.

  6. Robin Curtis

    Mark – thank you for this. A tragic loss.

  7. Peter Vaughan

    How very sad. He was such an inspiration. His book Sustainable Energy without the hot air was/ is a classic. As he said at last one can ask sensible questions ablout the numbers involved in providing UK energy from renwable sources.

    I have been discussing the ability for the UK to provide all is energy from renewables with colleagues for over 40 years. David MacKay’s book enables this discussion to propose realistic scenarios. He will be greatly missed.

  8. James Hollow

    Sincere sympathies Mark – I had not realised you and Prof MacKay were so close. I was so shocked and devastated by the news and I never even had the fortune to meet him in person.
    Given that thank you so much for writing this post. It could not have been easy, but it helped me come to terms with the tragic news, and clarified what we must endeavour to do lest so much of David’s work be wasted.
    “[we] just want to be given the answer by someone super-smart that we trust, and thereby be told what to think. But David wouldn’t be drawn into handing out easy answers,..” How true.

  9. Martin Nicholson

    There is an old saying that rings so true for David:

    “Only the good die young”

    1. Clyde Davies

      Well, that means we’ll be cursed with the likes of Mike Adams for eternity.

    2. Martin Nicholson

      Sorry 🙁

  10. Tom Blees

    Mark, once again your prodigious literary skills are put to good use in eulogizing one of the most exceptional people I’ve ever had the pleasure to know. Again, you’ve made my job easier. I’ll link to this page from my own modest eulogy at our website so our readers can have the benefit of your very personal tribute.

    1. Mark Lynas (Post author)

      Thanks Tom. From you that means a lot. Best, Mark

  11. Prashant Vaze

    Lovely eulogy Mark. I used to know David as a class mate in Newcastle-under-Lyme and so much of what you say stirs up old memories. I was even exposed to the explanation about Bayesian statistics he gave you; and had difficulty grasping the difference. (You might be interested in this – http://blog.keithw.org/2013/02/q-what-is-difference-between-bayesian.html). Thanks for this and the obit in the Guardian

  12. Graham Swift

    I had the good fortune to have known David (and also his brother Robert) at Newcastle High School , where I was a member of the maths department. I have a copy of his classic book which he gave to me , personally dedicated.
    He was a very modest young man , but kept contact with several of his school contemporaries and former teachers. Indeed three of them met him in Cambridge only a few weeks ago where he arrived for lunch on his usual means of transport , his bicycle. Likewise I had an email from him fairly recently , and we all communicated on Facebook. We shall all miss him.

  13. Roberto Zavattiero

    A very good tribute to David and how the book came about and how intellectually generous David was can be read here


  14. John Stumbles

    Here’s a nice obituary of David from Niall Mansfield, his publisher at UIT:

  15. Edward Davey

    A lovely set of tributes: thank you, Mark. Really touching. David was a wonderful man. All best wishes.

    1. John Stumbles

      I have collected links to Mark’s and others’ tributes, and added some comments of my own, here:

  16. Pilgrim Beart

    Great post, thanks. I knew and hugely respected David.
    Like you I hoped that Addenbrookes would follow-up on his post about ward temperatures, so I contacted the Chair, Jane Ramsey and now have a meeting scheduled next week with the Chief Nurse and the Director of Estates. Hopefully they’ll be receptive so the next question will be: “how do we solve the problem?”. At that point I may well be trying to tap into the large number of brains that David inspired for possible solutions.


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