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Strange7 comments on Pascal's Mugging: Tiny Probabilities of Vast Utilities - Less Wrong

39 Post author: Eliezer_Yudkowsky 19 October 2007 11:37PM

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Comment author: Strange7 19 August 2011 10:49:15PM 1 point [-]

Not the way I do the math.

Let's say you're a sociopath, that is, the only factors in your utility function are your own personal security and happiness. Two unrelated people approach you simultaneously, one carrying a homemade single-shot small-caliber pistol (a 'zip gun') and the other apparently unarmed. Both of them, separately, demand $10 in exchange for not killing you immediately. You've got a $20 bill in your wallet; the unarmed mugger, upon learning this, obligingly offers to make change. While he's thus distracted, you propose to the mugger with the zip gun that he shoot the unarmed mugger, and that the two of you then split the proceeds. The mugger with the zipgun refuses, explaining that the unarmed mugger claims to be close personal friends with a professional sniper, who is most likely observing this situation from a few hundred yards away through a telescopic sight and would retaliate against anyone who hurt her friend the mugger. The mugger with the zip gun has never actually met the sniper or directly observed her handiwork, but is sufficiently detered by rumor alone.

If you don't pay the zip-gun mugger, you'll definitely get shot at, but only once, and with good chances of a miss or nonfatal injury. If you don't pay the unarmed mugger, and the sniper is real, you will almost certainly die before you can determine her position or get behind sufficiently hard cover. If you pay them both, you will have to walk home through a bad part of town at night instead of taking the quicker-and-safer bus, which apart from the inconvenience might result in you being mugged a third time.

How would you respond to that?

I don't need to be psychic. I just do the math. Taking any sort of infinitessimally-unlikely threat so seriously that it dominates my decisionmaking means anyone can yank my chain just by making a few unfounded assertions involving big enough numbers, and then once word gets around, the world will no longer contain acceptable outcomes.

Comment author: DanielLC 20 August 2011 03:46:43AM 3 points [-]

In your example, only you die. In Pascal's mugging, it's unimaginably worse.

Do you accept that, in the circumstance you gave, you are more likely to be shot by a sniper if you only pay one mugger? Not significantly more likely, but still more likely? If so, that's analogous to accepting that Pascal's mugger will be more likely to make good on his threat if you don't pay.

Comment author: Strange7 20 August 2011 10:02:17AM 1 point [-]

In my example, the person making the decision was specified to be a sociopath, for whom there is no conceivable worse outcome than the total loss of personal identity and agency associated with death.

The two muggers are indifferent to each other's success. You could pay off the unarmed mugger to eliminate the risk of being sniped (by that particular mugger's friend, at least, if she exists; there may well be other snipers elsewhere in town with unrelated agendas, about whom you have even less information) and accept the risk of being shot with the zip gun, in order to afford the quicker, safer bus ride home. In that case you would only be paying one mugger, and still have the lowest possible sniper-related risk.

The three possible expenses were meant as metaphors for existential risk mitigation (imaginary sniper), infrastructure development (bus), and military/security development (zip gun), the latter two forming the classic guns-or-butter economic dilemma. Historically speaking, societies that put too much emphasis, too many resources, toward preventing low-probability high-impact disasters, such as divine wrath, ended up succumbing to comparatively banal things like famine, or pillaging by shorter-sighted neighbors. What use is a mathematical model of utility that would steer us into those same mistakes?

Comment author: DanielLC 22 August 2011 11:08:43PM 1 point [-]

Is your problem that we'd have to keep the five dollars in case of another mugger? I'd hardly consider the idea of steering our life around pascal's mugging to be disagreeing with it. For what it's worth, if you look for hypothetical pascal's muggings, expected utility doesn't converge and decision theory breaks down.

Comment author: TraderJoe 17 May 2012 03:24:36PM 6 points [-]

Let's say you're a sociopath, that is, the only factors in your utility function are your own personal security and happiness.

Can we use the less controversial term 'economist'?

Comment author: Relenzo 25 October 2016 01:37:30AM 0 points [-]

I think this answer contains something important--

Not so much an answer to the problem, but a clue to the reason WHY we intuitively, as humans, know to respond in a way which seems un-mathematical.

It seems like a Game Theory problem to me. Here, we're calling the opponents' bluff. If we make the decision that SEEMINGLY MAXIMIZES OUR UTILITY, according to game theory we're set up for a world of hurt in terms of indefinite situations where we can be taken advantage of. Game Theory already contains lots of situations where reasons exist to take action that seemingly does not maximize your own utility.