Because in a blackmail, I do not wish the trade to happen at all.
Something has to happen, and you must choose from the options you’re dealt. Maybe I don’t wish to pay for my Internet connection, and would rather have the Flying Spaghetti Monster provide it to me free of charge, and also grant me $1000 as a bonus? This seems to qualify as not wishing I had to choose a provider at all. But in reality, I have to choose, and FSM is not available as an option, just as not being blackmailed is not available as an option (by assumption; the agent doesn’t need to know that, only the problem statement that logically implies that).
The difference is that since blackmail is costly, there is no incentive to blackmail someone who will not give into it, which makes people who won’t give in better off than people who will. On the other hand, there is no incentive for a company to offer free services to someone who refuses to ‘give in’ and pay money.
I think the logic is along the lines of “make the decision which, if the other party knew you were going to make it, would maximise your expected utility”.
Which shows exactly why the rule is not universally applicable—the other party does not, in general, know what decision you’re going to make (though they can predict it to some level of accuracy), and so there’s a cost/benefit situation.
Yes, I was not entirely straightforward in my questions and wished to elicit some clarity from others. Here, the key is the difference between observational (logical) impossibility and agent-provable impossibility.
Something has to happen, and you must choose from the options you’re dealt. Maybe I don’t wish to pay for my Internet connection, and would rather have the Flying Spaghetti Monster provide it to me free of charge, and also grant me $1000 as a bonus? This seems to qualify as not wishing I had to choose a provider at all. But in reality, I have to choose, and FSM is not available as an option, just as not being blackmailed is not available as an option (by assumption; the agent doesn’t need to know that, only the problem statement that logically implies that).
The difference is that since blackmail is costly, there is no incentive to blackmail someone who will not give into it, which makes people who won’t give in better off than people who will. On the other hand, there is no incentive for a company to offer free services to someone who refuses to ‘give in’ and pay money.
I think the logic is along the lines of “make the decision which, if the other party knew you were going to make it, would maximise your expected utility”.
Which shows exactly why the rule is not universally applicable—the other party does not, in general, know what decision you’re going to make (though they can predict it to some level of accuracy), and so there’s a cost/benefit situation.
I am going to try and save my attempted solution ( http://lesswrong.com/lw/39a/unpacking_the_concept_of_blackmail/342c?c=1 ) from being stuck at the bottom of the thread. This might be inappropriate behavior, and if so please inform me.
I think you’ve answered your own question in your comment.
Yes, I was not entirely straightforward in my questions and wished to elicit some clarity from others. Here, the key is the difference between observational (logical) impossibility and agent-provable impossibility.