How many lives does a doctor save?

[This is cross posted on 80,000 hours: 1 2 3. Particular credit to Ben Todd for basically writing the third section.]

Doctors have a pretty solid reputation as do-gooders. There are regular news stories about how advances in medical science promise to help more people than ever before. Many of us have had the experience of being ill, seeing our doctor, and being made better.

So it seemed a pretty good career move for a 17-year old wanting to make a difference. Like thousands of others, I applied to read medicine. This is what I wrote on my personal statement:

I want to study medicine because of a desire I have to help others, and so the chance of spending a career doing something worthwhile I can’t resist. Of course, Doctors don’t have a monopoly on altruism, but I believe the attributes I have lend themselves best to medicine, as opposed to all the other work I could do instead.

Was I right? Is medicine a good career choice for someone wanting to ‘make a difference’? Continue reading “How many lives does a doctor save?”

Talks on Giving What We Can

I’m involved with Giving What We Can, a community that pledges to give 10% of their income to whatever best helps in the fight against global poverty. I’ve done a few talks on this over the years, here are the Prezi’s. Feel free to re-use them or their contents (most are permutations on similar points, although the tone and emphasis has varied depending on the audience – it is worth noting many of the figures are a bit out of date). If you want me to give a talk, get in touch! Continue reading “Talks on Giving What We Can”

Why you shouldn’t believe the resurrection happened

The 12th (and final) part in “20 Atheist answers to questions they supposedly can’t.”

  1. What accounts for the empty tomb, resurrection appearances and growth of the church?

Short answer: We shouldn’t be that confident of these facts, but in any case the base rate fallacy and selection bias nixes the confirmatory power.

Longer answer: The argument implied in the question is that the historical record of Jesus provides strong evidence to believe he actually died and rose again, which provides evidence that Christianity’s central claims (e.g. God exists, Jesus is the son of god) are true. The question neatly summarizes the three main ‘planks’ of evidence usually offered:

  1. The Empty Tomb. When Jesus died, his body was placed in a tomb. Not only was a stone rolled in front of it, but also the authorities posted sentries outside the tomb to stop anyone stealing the body. Despite this, the stone was discovered to be rolled away, and the body had gone. (e.g. Mark 16:4, Luke 24:2-3)
  2. Resurrection appearances. Several different groups of people (the disciples, some women, etc.) are reported to have seen Jesus after he died. (e.g. Luke 24:15-31, 36-48; Matthew 28:9-10)
  3. The growth of the church. After Jesus died, his apostles (and figures like Paul) were committed to the message of Jesus, and helped the church spread rapidly. (cf. Acts, but also the historical record re. the Holy Roman empire, etc.)

The idea is this data is very hard to explain via purely atheistic means. Maybe Jesus didn’t really die, but is it plausible he could have got up and escaped the guarded tomb after being crucified and speared for good measure? Maybe the disciples managed to steal the body, but how did they manage to get that past the guards? (And what was in it for them? Why would many of them go on to die for a belief they knew to be false?) Maybe the appearances of the resurrection were just hallucinations, but how could there have been so many hallucinations, of so many different people, and why didn’t the authorities just squash the story by presenting the public with Jesus’s corpse?

So, it’s argued, the best explanation for the historical data is the Christian one: Jesus rose from the dead and left the tomb miraculously, and then appeared to people like the apostles and women who visited the tomb, and these people, convinced by the truth, to go on and grow the church. Continue reading “Why you shouldn’t believe the resurrection happened”

Why the tails come apart

Many outcomes of interest have pretty good predictors. It seems that height correlates to performance in basketball (the average height in the NBA is around 6’7″). Faster serves in tennis improve one’s likelihood of winning. IQ scores are known to predict a slew of factors, from income, to chance of being imprisoned, to lifespan.

What’s interesting is what happens to these relationships ‘out on the tail’: extreme outliers of a given predictor are seldom similarly extreme outliers on the outcome it predicts, and vice versa. Although 6’7″ is very tall, it lies within a couple of standard deviations of the median US adult male height – there are many thousands of US men taller than the average NBA player, yet are not in the NBA. Although elite tennis players have very fast serves, if you look at the players serving the fastest serves ever recorded, they aren’t the very best players of their time. It is harder to look at the IQ case due to test ceilings, but again there seems to be some divergence near the top: the very highest earners tend to be very smart, but their intelligence is not in step with their income (their cognitive ability is around +3 to +4 SD above the mean, yet their wealth is much higher than this).[ref]Given income isn’t normally distributed, using SDs might be misleading. But non-parametric ranking to get a similar picture: if Bill Gates is ~+4SD in intelligence, despite being the richest man in america, he is ‘merely’ in the smartest tens of thousands. Looking the other way, one might look at the generally modest achievements of people in high-IQ societies, but there are worries about adverse selection.[/ref]

The trend seems to be that even when two factors are correlated, their tails diverge: the fastest servers are good tennis players, but not the very best (and the very best players serve fast, but not the very fastest); the very richest tend to be smart, but not the very smartest (and vice versa). Why? Continue reading “Why the tails come apart”

How good were the ancient greats?

Summary: In many fields, the ‘greatest’ (be they philosophers, playwrights, composers, etc.) are selected disproportionately more from those who lived in the distant past. I speculate as to what might be driving this bias towards ‘ancient greatness’, but one important takeaway is that we can be confident that the greatest of the past are likely inferior to the greatest amongst us today in terms of ‘innate ability’. So perhaps we should not regard them so highly.

[Very rough draft: advice/criticism on data, analysis, or style welcome, as is advice on whether this is worthy of going into academia, and if so how. Thanks to Rob Wiblin, Will Crouch, Catriona McKay, and Sam Bankman-Fried for ideas/prior discussion.]


If you look at a field of human endeavour (mathematics, philosophy, the arts, military strategy – pretty much anything) the reputedly ‘greatest ever’ in these fields have tended to live in the distant past.
Take philosophy as an example. Polls of the ‘greatest philosopher’ of all time broadly agree on a corpus of ‘ancient greats’. Here’s the top ten from a poll from Brian Leiter’s philosophy blog, with their dates added:

  1. Plato (428-348 BC)
  2. Aristotle (384-322 BC)
  3. Kant (1724-1804)
  4. Hume (1711-1776)
  5. Descartes (1596-1650)
  6. Socrates (469-399 BC)
  7. Wittgenstein (1889-1951)
  8. Locke (1632-1704)
  9. Frege (1848-1925)
  10. Aquinas (1225-1274)

The list is dominated by ancient Greeks and enlightenment Europeans, with only a couple of thinkers in the last couple of centuries getting a look in. I think Leiter’s poll (modulo some quibbles with the exact ordering) broadly captures the consensus view amongst who are the greatest philosophers, at least in the western tradition.

On the face of it, having the ‘greatest ever’ philosophers spread out from antiquity to the present day seems plausible. But consider how the human population has grown over time (data from Wikipedia):


The population has grown dramatically, so if we think about birth order rather than time, the greatest philosophers were generally among those born first. Why? Continue reading “How good were the ancient greats?”

Off duty

“Hi, single to the hospital, please.”

“You’re not ill, are ya?” The bus driver teased.

“No-no, I’m just training there.”

He let her go with a laugh and she walked up the aisle of the bus. The white tunic with blue trim poking out from under her coat made me guess student nurse. I was next in the queue; the driver spared me the same joke when I asked for the same ticket. Continue reading “Off duty”


I am now a doctor. The result that I passed my finals came on Friday, and the declaration happened Sunday afternoon. I start work as the most junior of junior doctors – a Foundation Year 1 – at the end of July in Milton Keynes. So now you know where to avoid if you get sick in August.

Traditionally (at least in the ‘States) students have a valedictory address at the end of their course, given by the top-ranked student of the year. This is a less auspicious farewell: I am a long way down any order of merit you care to name, and medical school has been a struggle. Things did get better in my final year, but the last six years haven’t been some Bildungsroman of how I transformed from spotty student to modern medical professional.

I’m still scared I’m not good enough. From what I haven’t done (at least, not on a non-plastic patient), from what I don’t know, to when I haven’t listened, there are fertile grounds for doubts. I find my mind keeps racing from these defects to hypothetical disaster. Although the medical profession is sane enough to carefully circumscribe the responsibility of junior doctors like me, this is still much more than I ever had as a student, and the excuses (“sorry, just a student, I’ll go and get a doctor”; “I can learn that later, I’m not qualified yet”) are gone. I feel like I am playing catch-up to the doctor I want to be, and I haven’t even started. Continue reading “Valediction”

Unfriendly AI cannot be the Great Filter

Summary: The fact we do not observe (and have not been wiped out by) an UFAI suggests the main component of the ‘great filter’ cannot be civilizations like ours being wiped out by UFAI. Gentle introduction (assuming no knowledge) and links to much better discussion below.


The Great Filter is the idea that although there is lots of matter, we observe no “expanding, lasting life”, like space-faring intelligences. So there is some filter through which almost all matter gets stuck before becoming expanding, lasting life. One question for those interested in the future of humankind is whether we have already ‘passed’ the bulk of the filter, or does it still lie ahead? For example, is it very unlikely matter will be able to form self-replicating units, but once it clears that hurdle becoming intelligent and going across the stars is highly likely; or is it getting to a humankind level of development is not that unlikely, but very few of those civilizations progress to expanding across the stars. If the latter, that motivates a concern for working out what the forthcoming filter(s) are, and trying to get past them. Continue reading “Unfriendly AI cannot be the Great Filter”