Knives are dangerous, so why do we use them?

Speaker A: 00:00:00

Hello and welcome to the Cognitive Engineering Podcast produced by me, Fraser McGruer, for Aleph Insights. In this series of podcasts, we take a look at interesting topics and discuss what we think they tell us about analysis and decision making. I'm here with Nick Hare and Peter Coghill of Aleph Insights, and this week we're discussing the fact that knives are dangerous, so why don't we ban them?

Speaker B: 00:00:25

Nick, let's ban knives. They're dangerous. Yeah, so the context here is that there was a recent terrorist knife attack in South London, Streatham, where I think several people were hurt by a guy called Sudesh Aman. So, you know, it's a bit low level, isn't it, for a terrorist attack? But the point is that knives are much easier to get hold of. I don't know if you know this, but they're much easier to get hold of than, say, bombs. So the knife was his weapon of choice. Now, he didn't kill anyone. I think he injured quite a few people, but the only person who actually ended up dying was him when he was killed by armed police. Now, yes, now, this is a typical Aleph Insights question, right? Because most people think, what are you talking about? Are you nuts? Like, of course, we're not going to ban knives. But actually, there may be other ways to do the things that we do with knives. Peter probably has some technological solutions. So the problem of chopping food up, that are safer than knives, and, you know, which can't be taken out and used in public. So, you know, we more or less ban guns. Why can't we do the

Speaker A: 00:01:42

same with knives? So yeah, I think this is a short podcast, we'll be wrapped up in a minute or two, because I think the answer is in the question, actually, the way we posed it, which is that you said two things. One of the things you said is quite low level, you know, I think we all agree that knives, you know, don't cause as much damage as bombs, and sorry, are more, sorry, it's easier to access knives than it is to access bombs. One, and two, and you said then the police turned up and the only person who did get killed was the individual himself who was shot by the police. So I think the answer isn't, isn't this the answer? Yeah, he brought a knife, he literally brought a knife to a gunfight. Yeah, is the knives are dangerous, but they're kind of not that dangerous, or they're not dangerous enough. And they're not as dangerous as guns. And they're not as dangerous as bombs. That is the answer, is it not, Peter? Well, yeah, I kind of thinking along

Speaker C: 00:02:33

your lines there, Fraser, when I was, when I was looking at this, I was trying to, trying to work out how society goes about deciding what gets banned and what doesn't get banned. And I started, you know, breaking it down, as an analyst would, I thought, two by two matrix, I need a two by two here. So I came up with, I came up with a two by two. So horizontal axis, you've got safe on one end, dangerous on the other. Yes. Okay, got that. Vertical axis. Yeah, it's gonna be, hold on, vertical is usefulness? No, yeah, yes, it's usefulness. But it's like, I had like, how many uses does that one object have? Ah, okay, gotcha. So, so starting from sort of single use, or in fact, you could push this into the negative, but say single use, the thing only has one use, going up to sort of multiple, many multiple hundreds of thousands of uses. Is its use rivalrous, I think

Speaker B: 00:03:29

is the thing there? Could be, yeah. Like, does you using it stop it from being used somewhere else?

Speaker C: 00:03:34

No, no, no, it's like, no, not, can you use it more than once? It's like, can you use that thing

Speaker B: 00:03:39

for more than one thing, for different things? Yeah. Oh, so it's kind of how, uh, multi, it can be used for multi-purpose. It's like, it's sort of expected. Single purpose versus

Speaker C: 00:03:48

multi-purpose. Yeah, yeah, it's kind of like overall usefulness, um, as a thing. Oh, yeah,

Speaker B: 00:03:54

okay, right, kind of generally, what can you do with this item? Yeah, so, so let's take an extreme

Speaker C: 00:03:59

example. So, nuclear bomb, single use. Yeah. Uh, very dangerous. Yeah, pretty dangerous, yeah. Definitely in the ban zone. Well, yeah, but we've still got some. Well, hold on, let's hear this, I'm talking, like, the ban, the ban. I know, I'm just, just playing with it, I like it. Define, define the ban zone as, like, things that you can own as an individual, right? Um, handgun, UK, okay, handgun in the UK. Single use, really, it's designed for killing people. Yep, yep. Uh, you might say you could do target shooting, but okay, that's two uses, find a third, dare you. Um, uh, less dangerous. Hammering a nail. But anyway, less, less dangerous than nuclear bombs. Yeah. But in the ban, in the ban. Although, they've killed more people than nuclear bombs. Yes, they have, yeah. You know. Um, then, then, right, another example, street extreme, softball. So, like, the soft, the softball, you play softball with, like, a big soft tennis ball-y type thing. Yeah, yeah, yeah. Pretty undangerous, you can't, you'd have to

Speaker B: 00:04:54

really throw it very hard to hurt somebody with that. Um, 169,000 people a year are killed, uh, sorry, are injured in the US through, uh, baseballs and softballs each year. Okay, but that's quite, yeah, okay. How many are killed? But anyway, they're not undangerous. I don't know, I don't know, but I would

Speaker C: 00:05:11

imagine baseballs are doing most of the work there. Yeah, yeah, and possibly bats, I don't know if they've broken it down by, you know, what the motive of injury, but yeah, okay, so pretty undangerous, we'll agree, uh, and single use, but not in the ban zone, so it's not to do with solely how much useful it is, but it's sensitive to both how useful it is and how dangerous it is. Right, so knives, I've got them, they're really useful, you can use them for all sorts of things, uh, so they're right at the top in terms of usefulness, they're kind of middling in dangerousness, but they're not in the ban zone. Right, so the line of banage is a sort of diagonal line that cuts down. Knives are

Speaker B: 00:05:46

on the good, they're on the good side. They're on the good side, yeah, they're on the good side.

Speaker C: 00:05:51

Uh, another extreme example, spoons, um, middlingly useful, um, uh, definitely not in the ban zone. Well, you know, I think you could probably list as many uses for a spoon as you could for a knife. Yeah, you could, okay, approximately about as useful, but they're much less dangerous than knives. That's true, you never hear about terrorists trying to attack people with spoons. No, I think that's probably in the terrorist manual, uh, if a knife is available. Yeah, day one terrorist school, don't bring a spoon to a knife fight. Yeah, um, so yeah, it's a diagonal line, so I, this made me, made me think that society's possibly sort of, um, converged on a sort of estimation of the sort of sum of all utilities divided by the sum of all fears or the sum of all dangers. Uh, as long as it meets some sort of threshold, it'll be in the allowed zone and not in the ban zone. Yeah. Um, so yeah, that was kind of the extent of my thinking.

Speaker B: 00:06:49

Obviously, you know, the literature on risk and, um, you know, and what we choose to ban and so is littered with examples where it doesn't work. I mean, you, you know, although I totally agree. I mean, in a sense, not just are you observing something, but that is really ought to be how we do it. It ought to be the case that we're doing it on some balance between costs and benefits, but, you know, so drugs, the classic example, marijuana v alcohol, you know, where that yes, marijuana has, you know, the fact that I think it's harms have been downplayed a bit because there are harms sort of psychiatric issues and so on. But, um, but in general, they're much, much lower than alcohol. Um, and yet, um, you know, yet we, and I mean, there's no reason to suppose, I don't think that the benefits side that alcohol is particularly more or less enjoyable than marijuana, if anything is probably on the slightly less side. And yet we've marijuana is still here, still criminalized, whereas alcohol isn't. Um, and, and, you know, and you look at, if you look at, sort of activities that are banned, such as, you know, not wearing your seatbelt, which is, yeah, it's pretty dangerous, but it's not as dangerous as climbing Mount Everest, you know, for a particular trip. And yet we don't, we don't, uh, yeah, we don't, we don't stop people from climbing Mount Everest. There's a whole load of dangerous.

Speaker C: 00:08:12

I'm not saying it's a pure calculation, but it sort of approximates this, but yeah, you can, but I've given one another example. I've seen a transition from the good zone to the band zone. Oh, okay. So plastic bags. Yes. Okay. Pretty bloody useful things. You could do quite a lot of stuff with them. So they're kind of middling in the usefulness. I suffocate people with them, which is really particularly useful. Yeah. But they are, they are, they have an inherent danger in terms of suffocation. They have a, they have an inherent badness in terms of the environment, et cetera. So as we've become more aware of the badness and the sort of societal expectations, they have moved over, they've moved along the dangerous axis and are now kind of in the band

Speaker B: 00:08:54

zone. Yeah. Yeah. But again, I mean, I can't help thinking that the reason that we banned plastic bags is because of that documentary with the, with the sad whale mum and her dead baby, rather than because, I mean, there's so many other things that we do that reek vastly more ecological damage, you know, in terms of sort of flights, taking a flight somewhere. If you take one flight a year, you've more or less undone any amount of, you know, light bags for life that you've bought. It depends how many bags for life you've got. If you've got millions of them. Well, that's the, and that's another problem. I feel like, I think I've, I think each bag for life is worth about a hundred plastic bags and I keep buying them because sometimes I can't, I don't realise I need to get to the shops till I'm already out.

Speaker A: 00:09:37

Um, so where are we? I think we've covered this really well, really quickly, actually. And I like, I like Peter's matrix system there. Um, I mean, isn't that it? We've, we've talked about it.

Speaker C: 00:09:50

We've, we, you know, we've. Not quite. No, because it, because Nick's, I think where Nick's going is that it's not just about like the, the overall cold measurable utility of a thing. Yeah. It's about the, it's also about like messy, human-y things like the, um, how much we are willing to ignore the fact that there are dangers of this thing, uh, or how much we're willing to conveniently ignore the fact that, that flights are bad for the environment, et cetera. But also messy human things like the, um, the intended, the intended use of that person with a particular item, uh, complicate things. So another thing on my two by two swords, right? A sword is like a big knife. It is like a big knife. But actually because of it's like, it's like a extreme knife. It's actually got fewer uses. It's really only designed for stabbing people and looking at. What about chopping really big cakes? Well, yeah. Okay. The free, how often do you chop a really big cake? Very rarely. Well, if I had a sword, I might find more excuses. And opening, of course, opening champagne bottles. That's another thing. But, um, but you know, there's not a, I don't think there's a big culture in the UK for owning swords as things to look at. That's kind of, uh, there are other places that say cultural reasons in Japan and things, but here we don't really have a culture of sword ownership. Um, but somebody with a sword, you, you wouldn't, if you saw somebody with a sword walking down the street, you should probably run the other way because

Speaker B: 00:11:21

there's a, likely that they have ill intent. Unless they're dressed like a medieval knight, because they're probably off to a fun medieval fair somewhere and you should follow them.

Speaker C: 00:11:30

Yeah. So history, they say my swords are creeping up my scale now. Historical reenactments is another use for them. But those swords are play swords. They're not sharp. They're not, they're,

Speaker B: 00:11:39

they're just lumps of steel. I've been to, I've been to certain medieval places where there's like mad sword guys from Germany who, you know, really into getting there, getting there, but yeah.

Speaker C: 00:11:52

Anyway. Um, so yeah, I take the point. I'll take your point. So it's not just, you don't just ban knives. You ban knives with a certain intent. So you can't have, you can't walk around the street with knives unpackaged. So you can walk back from the shop having bought some knives to your house, fine. But you can't walk around with a concealed knife, which is, I think the definition involves it's a knife that's not, uh, that's not, you're not advertising the fact that you've got it and

Speaker B: 00:12:18

it's unpackaged so that it's ready to be used. What about combat? Is there a distinction drawn between combat knives and sort of kitchen knives? No, I think it's any, I think concealed knives. It's not somehow more illegal to have one of those combat knives.

Speaker C: 00:12:33

Yeah, there are illegal knives in this country. So sort of butterfly knives and flick knives

Speaker B: 00:12:39

and things there they are. Is that because they become, they're automatically concealed by their

Speaker C: 00:12:44

very nature? Yeah. This is it. This is like, there's an inherent intent with that item that you have. So handguns, there's no reason to have a handgun other than to kill people. Yeah. That's what handguns are built for. Um, so they're banned. And I think that's part of the ban, they're part of the sort of equation for banning them. Flick knives and butterfly knives and other knives, which are really only intended for fighting with, they're banned because they're not, they don't make good kitchen knives. They're not, they don't have that sort of, there's an implicit reason for having it and that's for stabbing people. So that's part of the equation for banning them. That approximates this kind of utility versus risk function. Well, again,

Speaker A: 00:13:27

I returned, I think we've wrapped this up. I mean, what more else? What else is there to say?

Speaker B: 00:13:31

Well, I can start telling you about what things are most, cause the most injuries.

Speaker C: 00:13:34

Well, famously, I've got a fun list of weird things that are banned around the world.

Speaker A: 00:13:39

Oh yeah. Okay. Well look, I mean, cause perhaps Peter's thing sounds more fun than mine. So

Speaker B: 00:13:44

maybe if I kick off and then Peter can get into the even more fun stuff. Well, famously swimming

Speaker A: 00:13:47

pools, right? They're meant to be more, so they're more dangerous than, having a swimming pool in your back garden is more dangerous than having a gun locked away. Oh yeah, for sure. Yeah. So I

Speaker B: 00:13:57

dataset ran from, I think the: 1950

Speaker A: 00:16:31

Yeah, quite a sort of negligible my time spent with a fence. Now stairs, everyone knows stairs

Speaker B: 00:16:36

are dangerous. They're top of the list. 3 million stair related injuries, right? Okay. But fences are 100,000, which is one 30th of that, right? But I reckon I spend a lot less than one 30th of my time near a fence than I do. So where I'm going with this is fences are bloody dangerous. Like,

Speaker A: 00:16:54

don't let that number fool you. But what's happening? Are people like impaling themselves on them or, or standing next to them on windy day getting crushed? I would imagine that the

Speaker B: 00:17:02

thing here is people just trying to hop over a fence. Yeah. You know, something that I, we probably all do at some point. But so I think the takeaway there is don't hop over fences. But anyway, then moving up the list, we've got trampolines, workshop tools, glass doors, actually cause less injuries than other doors. I think in the US fencing is quite a big business

Speaker C: 00:17:24

with all the big ranches and things. And the process of putting them in is quite industrial and fast and people lose hands and things all the time with it. So it might be that.

Speaker B: 00:17:34

I don't know. I feel like this is people getting injured through contact with fences rather than people getting injured working on the building fences. But I don't know, cans and containers, very dangerous. Nearly 300,000 injuries a year, cans and containers there. But moving up, unsurprisingly bicycles, 424,000 injuries of bicycles a year, but actually narrowly beaten by one of the worst enemies in the house, the simple clothing. People's 427,000 injuries related to clothing every year. I would imagine this is people tripping over their trousers or something. Fly zipper injuries. Oh don't. But as I said, the top five, exercise equipment. Yeah. Okay. Yeah. Not surprisingly, I guess. Bathroom furniture where it's all slippery. Yeah. Chairs. Yeah. And we know stairs are at the top, but second, beds. Really? Beds. They're more like deads. Nearly 900,000 injuries a year. What are people doing with their beds? I guess maybe just simply falling out of them. Yes. But I mean, 900,000 people a year, that's like one in 400 Americans are getting injured with a bed each year. Yeah. Okay. So yeah, double-decker beds. Yeah. I mean, I actually, one of the worst injuries I've ever had was bed related, but it's because I was jumping on the bed and then I fell off and bashed my eyebrow on the corner of the bed. Yeah. We'll call that a bed stroke trampoline

Speaker A: 00:19:16

injury, I think. Yeah. Good point. Was beds the top one? No, stairs are top. Oh, stairs are top. Stairs are top by a mile. Yeah. Yeah. Yeah. Yeah. Okay. So we need to live in a kind of, basically, yeah, we need to live in a- Ground floor. On the ground floor with your mattress on the floor.

Speaker B: 00:19:31

Yeah. Basically, don't heights, any kind of heights are bad for humans. Yeah. And don't with fences. Yeah. Sit on the floor. Yeah. Yeah. Bathrooms, basically, I think non-slip tiles. Yeah. Whatever you do, don't try and use exercise equipment. Yeah. So don't wash. Don't exercise. Sleep on the floor. Sleep on the floor. Sit on the floor. Basically,

Speaker C: 00:19:51

so weird things. Right. So in: 2010

Speaker A: 00:20:12

I know that in Iran, your haircut can be a, what's the word I'm looking for? An expression of dissent against the government. Could be. No, they are. They're very careful about that stuff.

Speaker C: 00:20:23

y is banned in Pakistan as of: 2007

Speaker A: 00:20:29

thing actually. Okay. And do you know the biggest expression of dissent is you had like, imagine Elvis with a great big bouffant. Okay. That is the haircut, the hairstyle. It's like the

Speaker B: 00:20:40

anti-fundamentalist hairstyle as against that as you can get. Yeah. Which by the way, is quite a good choice from the Iranians to ban that. Yeah. And I think they, yeah, haven't they got a set of... So in North Korea, there's only a set of haircuts. Yeah. They don't even ban haircuts. You're only allowed one of a certain small number. Exactly. And sorry, Peter, I interrupted you on

Speaker C: 00:20:59

the next one you went to. Well, in China, make sure if you're planning on being reincarnated, you get permission from the government first. Okay. So you're not allowed to just, you're not

Speaker B: 00:21:09

allowed to do an unauthorized reincarnation. Yes, exactly that. How do they enforce that?

Speaker C: 00:21:14

president of Turkmenistan in: 2005

Speaker A: 00:22:10

Is that the same guy who built the gold statue of himself that rotates? Yeah, the Turkmen bashing.

Speaker C: 00:22:15

Statue guy. He knows what he's on about. Yeah. And finally, North Korea don't wear blue jeans because blue denim is associated with the United States.

Speaker B: 00:22:24

Well, I imagine there's probably quite an extensive list of things you shouldn't do in

Speaker C: 00:22:27

North Korea. But blue jeans is definitely one of them. That's the one that's going to call you out as being an outsider. So is sort of holding a picnic in a park. So is being not very North Korean looking. Yeah.

Speaker A: 00:22:42

Okay. All right. Well, I like the way we went from, you know, knives to blue denim on that one and picnics. Keep it light, I thought. Keep it light. Yeah. Okay. Well, look, let's wrap it up there. I really enjoyed that. So thank you, as always, for listening to the Cognitive Engineering Podcast. I'm Fraser McGruer. We've been here with Nick Hare and Peter Coghill of Aleph Insights. Until next time. Goodbye.