David Spiegelhalter
Appearances
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Oh, I think it's fascinating. I mean, it's just part of being human. It's all around us. We don't know what's going to happen, and we don't know what's happening. We don't know what's happened, and we don't know why. And we live with that all the time, and we're happy with that. I mean, I always ask people, would you want to know how a football match was going to end if you had recorded it?
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And would you want to know what you're going to get for Christmas? And even... And, of course, they say no. And even, would you like to know when you're going to die? Which, of course, I can't tell them, but very few people actually say they would like to know. Some do, but very few. And so I always think of uncertainty as a relationship between ourselves and the outside world.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Somebody's called it the conscious awareness of ignorance, which I really like. Because it really puts that in something we own, you know, our personal ignorance. And that can vary so much from person to person.
Something You Should Know
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Well, I'm a statistician, so I've spent my entire career in a way analyzing uncertainty, using data and evidence to try to reduce our uncertainty and even try to quantify our uncertainty to actually get a handle on what we don't know. And I really strongly believe that we should, when possible, try to put our uncertainty into numbers.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
I mean, we all use words like could, perhaps, likely and everything in our everyday language. But actually, those can be very dangerous. And I always refer back to 1961 when Kennedy became president and found out about the CIA bombings. planned invasion of the Bay of Pigs at Cuba to topple Castro's government with 1500 Cuban exiles.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And he commissioned the Joint Chiefs of Staff to do an intelligence report on that. And they thought it was not a very good idea at all and thought that it was about 30 to 70 chance of success. In other words, 70 percent chance of failure. But in the report that went to Kennedy, the numbers got taken out and it got replaced by, bizarrely, the term a fair chance of success.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And they meant not very good. But I don't think that's how anybody else would interpret it. Of course, that's not the only reason he approved the raid, which, of course, was a complete fiasco. But people have learned from that. And now in intelligence, people really try to put numbers on their judgments.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
In the UK, if you're in MI5 or MI6 and you use the term likely, you mean between 55% and 75% probability. And if anyone assesses a 30% chance of success, they have to use the word unlikely to communicate that number. So there's a sort of lookup table between words and numbers.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yeah, I know. I mean, this has been studied for ages. I'm not a psychologist, but, you know, I think it's well known that, you know, people do have an anxiety about, you know, not having control of their lives. They feel particularly bad when, you know, something, risk might be imposed upon them by something else.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
They're particularly scared of things that they don't understand very well or have really dread results, giving people cancer and so on. And that makes people anxious about certain things where actually maybe They're not the main things they should be anxious about.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
When people started doing this research in the 1980s, microwave ovens came very high on the risk index in terms of people's fears and anxieties. And that's gone down. There's some fashions in risk in what people are anxious about and what they aren't. But it is true. Our feelings come into how we feel about risk and uncertainty all the time. We can't just...
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
wave our fingers at people and say, oh, how silly you are that you're worried about this and you're not worried about something else. I don't think we should do that. I think we should acknowledge people's concerns but try to give them the best evidence in the clearest way so that they can make an informed choice.
Something You Should Know
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We shouldn't be propagandizing people, trying to manipulate their feelings either to reassure them or to frighten them. And that's why in my work, I really push this idea of trustworthy communication. Why should anyone trust scientists, experts, authorities and things if they feel they're being manipulated?
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And that means actually giving people information that's balanced and that does talk about the benefits and harms, possibly of vaccines, for example. And, you know, perhaps don't use the phrase vaccines are safe and effective, but say, yeah, they're safe enough and effective enough to use in some people in some circumstances.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yeah, I like the idea of luck. I mean, I don't believe that luck is some external force that operates in our life. But I do think it's quite useful as a description, looking backwards at things that happened to us that were out of our control and were unpredictable and yet had a big impact, like winning the lottery or being knocked down by a car.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
So, you know, these are all things that could happen to us. And philosophers have identified, in fact, the most important type of luck is which is what's called constitutive luck, which is just who you're born as.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Actually, maybe even before that, there's existential luck, which is the luck of being born at all, because it's extraordinary that any of us are born, the chain of circumstances that are required for that. But given you are born, who you're born as in the world is incredibly important for the rest of your life.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
You know, who your parents are, the country, time of history, et cetera, especially your genes, you know, your early environment or so. You've got no control over these at all, and yet they're staggeringly important for the rest of your life. So that's the biggest bit of luck that you have, just who you are. And then, of course, you've got
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
what's called circumstantial luck, which is being at the right place at the right time, meeting your wife on a train, as somebody I know did, or being like my grandfather, being at the wrong place at the wrong time and being blown up by a shell in 1918 in the Western Front. And then you've got outcome luck, which is just how it happens to work out for you at that particular moment.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Like, you know, I know a friend of mine was on a plane that crashed. Seriously, nearly everyone on board was killed. Terrible circumstantial luck to be on that plane, but really good outcome luck because he survived. Similarly, my grandfather, actually the shell, you know, blew him up. But only not severely enough, he was taken off the front line and survived the war.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Otherwise, I wouldn't be here. Well, we're glad you are. Yeah, exactly. So am I. But I very nearly couldn't be, just like all of us. It is amazing that any of us are here at all, really.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yeah, again, I don't think there's some external force. I mean, people do talk about a force like synchronicity, which Jung invented, or seriality and things. I don't believe that. I think they just happen because there's so many opportunities for them to happen. And also, I think they happen because randomness, true randomness, is very clumpy indeed.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
You know, just because things are random, they're not equally spaced. So, you know, I know that if I've got 20 people and I ask them the last two digits of their cell phone number, there's an 87% chance that I'll get a match in that group of 20 people. And some people would think, oh, wow, what a coincidence. I think, no, it's utterly predictable that that'll happen.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
So, you know, the clumpiness of randomness leads to coincidences occurring, and they're quite difficult to interpret. And that's why anybody who talks about a coincidence, they really need to get some expertise in there to try to evaluate that. Our human intuition about it is terrible, absolutely awful, about probability in general. We're really bad at it.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Well, the standard one is if you have 23 people, then there's 50 50 chance of two of them will share a birthday. And that is something you find quite difficult. So on a soccer field, there's 23 players, 11 in each team and the referee. So in half of all soccer games, there's two people on the pitch with the same birthday. And that I think people do find quite difficult.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And it's shown, people have shown it again and again. So it works. and you can prove it mathematically fairly easily, but it is something that doesn't correspond to our intuition. But there are other things that go the other way. That's something that we think is, whoa, that's surprising that happens so often. The other thing that actually happens is surprisingly rare is shuffling a pack of cards.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Now, if I shuffle a pack of cards properly and give it a good shuffle, I could be absolutely confident, bet you all the money in the world, that nobody in the entire history of humanity has ever had the cards in that order before. And then I can shuffle them again into a good shuffle, and I say nobody in the entire history of humanity has ever had the cards in that order before.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And not just now, it's unbelievably unlikely that anyone ever And no two people in the whole history of humanity have ever had a pack of cards in the same order after a good shuffle. And people find that really difficult to believe because it's not intuitive just how many shuffles there are. And, you know, you can do the sums.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
It's sort of 52 for the first card and 51 choices for the second card and 50 for the third card. And you multiply all those numbers up together and you get a very good number. In fact, the number is about the same as the number of atoms in our galaxy. It's, you know, it's got 78 zeros, I think, beyond it. You know, it's an unbelievably massive number. And that's not intuitive at all.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yep, as many atoms as there are in the whole galaxy. And so the shuffle you come up with after a good shuffle, nobody will ever have done before. You can be almost certain of it. You can't prove it, of course. It's not logically true. But statistically, it is just unbelievably unlikely.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yeah, yeah, it is quite surprising.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
How would you ever know that? Yeah, how would you prove it? That's true. It is difficult because you can't prove it. You can't look at every snowflake. I don't know every shuffle that's ever been done. But you can do the sums and you can work out just how incredibly unlikely a match would be.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Yeah. Taleb uses the frame Black Swan, which is essentially a really completely unpredictable event that occurs and then people find an excuse for it. Perfect Storm is different. It's just a very extreme example of something fairly familiar. And, you know, the story I use is about this boat, the MV Derbyshire, which is twice the size of the Titanic, and disappeared without trace in 1974.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And so they had no idea what happened. And eventually they found, about 12 years later, they found the wreck. And there was an inquiry and two statisticians who I know took part in the analysis of that. And they had done simulations on wave tanks and things like this. And they worked out that the boat, it was in a typhoon, went into a perfect storm.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Suddenly, you know, a wave, they reckon, you know, it could have been 25 meters high. The entire weight of it went onto the front of the boat, the front hatch, and caved it in. And then there was a chain reaction, and all the, you know, the containers in the ship just sort of exploded, just, you know, caved in, and the ship went down in seconds. They didn't even have time to send a distress call.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And and that was they used this, you know, technical stuff of extreme value theory. But it was an example of a perfect storm in which an event happened that had never more extreme than anything that had ever been observed before. But with the appropriate analysis, you can show that it's quite plausible that it happened. What did you say about what's a black swan? Oh, a black swan.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
That was what the Taliban invented. A black swan is something that it's like, you know, people thought all swans were white. And then they went to Australia and found a black swan. And so it's something that you never even crossed your mind. A complete unknown unknown in Rumsfeld's language. So you never even crossed your mind that it was there. And then suddenly it's there.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And usually, of course, people then very quickly find a reason to explain why it happened. But it's a qualitatively different event from something that has happened before. And again, I think it's useful to distinguish that from a perfect storm, which is just an extreme version of something that is familiar.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
I got a few principles I do, which is try to... look at the possible futures, you know, try to think of what might happen, what might go wrong, and without getting too anxious about it, and then take some mitigating circumstances, you know, sort of buying insurance and stuff like that when you go travelling. Taking risks, but not being reckless.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
That's what I always say to kids when I talk about this stuff. Take risks, but don't be reckless. In other words, protect yourself against the severe downsides of what might happen.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
But go for it, because people have found that people who are considered lucky, well, actually, they've got particular personal characteristics of being bold, taking advantage of opportunities, for having a positive mindset of going for things, acknowledging it's not always going to work out. So I kind of think that I try to do that, but without being, I won't get on a motorbike, for example.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
I always think I would love it, but I'm not going to get on a motorbike. But I will go off and have other adventures, which I feel are okay. So I kind of try to weigh things up, not always using, not using numbers, but just trying to think about, you know, roughly what are the risks I'm concerned about.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
Oh, that's very difficult. There's huge variation. You must know in the people, you know, you'll know some people who are very cautious, rather anxious, always concerned, you know, one in a million chance. Well, there's always the one and things like that. And others who are more gung-ho and go for it and kind of ignore, you know, are not too sensitive, you know, are bold, possibly even reckless.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And so there's enormous variation in our reaction to it. I think what's more important, and that's how individuals are, people are different. When it comes to sort of societies, when people are making judgments on behalf of us, about what risks society is prepared to take, then I think, you know, it is interesting just how much cautious some
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
you know, some policies are compared with others just because actually people are really concerned about, for example, nuclear power or nuclear waste. And so vast amounts of money is spent to possibly have negligible effect in reducing the risk as the risk is so small in the first place. And so, you know, I think when it comes to societal decisions, we should be expecting people to take
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
I wouldn't say a rational, but a balanced approach to actually looking at the important things and not, I personally feel, not following people's anxieties.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
This is the important thing which I always emphasize, which is resilience. And the point is that, you know, we can't stop everything. Stuff happens. We can't stop everything bad happening to us and we're going to die anyway. So the crucial thing is resilience, which is being able to deal with stuff as it comes along of, you know, recover as best as you can.
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Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
And it's resilience to things you never even thought of. I mean, you can protect yourself to some extent against things you have thought of. But in the end, what one needs is reserves, both I think mental and monetary if possible, but certainly mental reserves to deal with unexpected things.
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The illnesses are going to happen, the dramas, the things are going to happen to the people around you, the people you love, You've got to be deal with it. That is how things go. And so I don't know if you can train people into resilience, but it's certainly a characteristic that is, I think, the most valuable thing to have in an age of uncertainty.
Something You Should Know
Cool Things You Can Do With AI & Surprising Insight in Chance, Probability & Risk
If I shuffle a pack of cards properly and give it a good shuffle, I can be absolutely confident. Nobody in the entire history of humanity has ever had the cards in that order before. It's not intuitive just how many shuffles there are. The number is about the same as the number of atoms in our galaxy.