all right everyone I just wanted to really briefly do a quick version of the prisoner's dilemma you'll definitely want to take a look at the written lectures for all the details but I just wanted to talk through it first because it can be a little hard to get your head around because it's kind of not the normal way we think about things there are good things about this way of thinking about it and bad but I just wanted to talk through it because that might make it a little bit easier and hopefully the audio quality on this one's not going to be as terrible as the other tries so we have ourselves two criminals rabbit Red Dog they have been caught they are complete strangers they do not care about each other all of those qualifications like I said in the written lectures all of the things that actually break a prisoner's dilemma in real life we want to assume away so we're gonna just assume that each of them only cares about doing the thing that's best for them they don't care about the other person they aren't ever going to interact again and there are no costs here beyond just the prison sentence so in this particular case snitches are not getting stitches or anything like that all right so what we're gonna do is we drive our little decision matrix or something and what you want to do is I guess on the Collins we're gonna think about possible things that are out of your control so we're going to assume just to draw this out we're going to assume that we're rabbit right so from rabbits perspective the things that that she has control over are the rows things read dog has control over are the columns so let's think about how how this can work so let's get a different color here for red dog I should have drawn this so close to the top oh well okay so red dog can either stay silent or red dog can write and rabbit can either stay silent or rat production quality is very high here let's now think about what can happen so if they both stay silent both of them are going to get the their second best outcome right rabbit is gonna get second best and in the written lectures I give you you know sort of possible sentences I tell the story a little bit more but let's not worry about that and then in the case where they both rat each other out they're both going to get their second worst outcome okay if rabbit keeps her mouth shut and Red Dog rats her out that is going to be the worst case scenario for rabbit right so rabbit sustained silent reading is reading so that's read dogs best and this is rabbits worst okay and this outcome here for for rabbit is called this one is the the suckers payoff it's a kinda terrible name but you know what else all right in the case where rabbit being a rodent rats out Red Dog and Red Dog being the loyal animal she is keeps her mouth shut well then we have the reverse we have the suckers payoff from Red Dog because now we have rabbits best and red dogs worst okay so now I went through the longer argument in the written lecture so you might think that if they're rational since they both are gonna do exactly the same things because all of the incentives are exactly the same for both of them again my world my example you might think that they converge on the co-operative outcome because if they both keep their mouths shut they can both get something that's better than what they're gonna end up with if they both rat each other out but that doesn't work because once you come to the conclusion that the other party so if rabbits thinking about it so if rabbit comes to the conclusion that Red Dog is gonna keep her mouth shut we're no longer sort of there's not two possible futures anymore because we know what's gonna happen right red dogs gonna keep her mouth shut even though she's very smiley she's gonna keep her mouth shut which means rabbits choosing now between her second best and her best outcome so she'll choose the thing that gets her the best outcome that means she'll rat and of course exactly the same thing is going to be true for Red Dog if Red Dog reasons that rabbit is going to keep her mouth shut because the cooperative thing is better than the second-worst outcome that they're both get if they've rat then Red Dog will decide that we are in sorry we're in the top row right so we know that rabbits gonna stay silent that means red dogs deciding between her second best and her best so that again means that she's gonna rat that means that both of them are gonna rat and they're both going to end up with their second worst outcome and so that last part is the the sort of shortcut version of the argument right it's just since there are only two possible futures here to worry about and we don't need to bring in probabilities because they're both rational we can just reason in the way I just said you just go okay imagine that so if you rabbit imagine that Red Dog is going to keep her mouth shut what should you do well you should choose if she's gonna keep her mouth shut you're choosing between second best and best so you should do the thing gets you the best so you should rat okay so imagine that Red Dog is now going to rap if Red Dog is going to rat then that means rabbit is choosing between her worst and her second worst and the thing that gets her second worst is to rat so she's going to rat so in both scenarios if Red Dog is silent she should ret if Red Dog rat she should rat so that means ratting is strictly dominant no matter what the other party does you should always do the same thing which in this case is rat each other out and that's the trap the fact that if the payoffs are structured like this then both parties if they're rational and again if these are the only considerations both parties will do exactly the same thing which is rat each other out and so if you are stuck in a prisoner's dilemma like this to get out of it you have to do something which changes the way the payoffs are structured you have to make it so that it's no longer better for both parties to rat no matter what the other party does and that's where things like personal connections friendships or threats of violence which change you know we're no longer just talking about number of years that's why those sorts of things change the payoff structure so again there are a lot of other details around this but leave that to the written lectures to go into just wanted you to have something that can spelled it out as best I can and there are more details that you will want to be aware of for when you go to do your assignments so see the written lectures Thanks