It is not a default, or an assumption, or anything but an objective fact that everyone involved is agreed about.
People are rarely in agreement about what disagreement point is. Especially if various entities have had a long-standing relationship with some changes.
I can’t fit this to any of the examples you gave. The Baron comes to the Countess with a threat to publish their correspondence: it is clear to both that he has unilaterally introduced a change to the status quo, to the Countess’ detriment. A McGuffin owner comes to a McGuffin collector offering a McGuffin at a fixed price: it is clear to both sides that this has introduced a new option, taking no existing options away. Everyone is in agreement. What situations are you thinking of that make “rare” the clarity of this distinction between threatening to injure and not threatening to injure?
And what about the variant when the winged sandal was going to be given to charity, but the Baron rushed in to prevent that, arriving just in time?
Here it’s clear that the Baron still has legal ownership (just!), but that it’s the Baron who’s changing the status quo.
You could argue that a lot of law is about specifying what the disagreement point is (generally through ownership rules and contract law), but that doesn’t mean that our legal system’s choice of disagreement point comes from any intrinsic definition that makes sense (see the difficulty with intellectual property).
I rather lost interest in the winged sandal story, but for all the attempted complications, it remains quite clear. The Countess never owned it, and the Baron wants to secure his ownership first before offering it for sale. Whatever this is, it is not blackmail. Engrossing, forestalling, regrating, badgering, or cornering), perhaps, which aren’t even illegal any more in English law.
A lot of law is about specifying exact rules. The difficulty of doing so, precisely enough to decide cases, does not imply that there is anything philosophically problematic.
The agreement they had: an explicit stipulation of a car for £100, and a reasonable presumption on both sides that the car would be black. Agent A is breaking the contract by demanding more. This is not a difficult example.
People are rarely in agreement about what disagreement point is. Especially if various entities have had a long-standing relationship with some changes.
I can’t fit this to any of the examples you gave. The Baron comes to the Countess with a threat to publish their correspondence: it is clear to both that he has unilaterally introduced a change to the status quo, to the Countess’ detriment. A McGuffin owner comes to a McGuffin collector offering a McGuffin at a fixed price: it is clear to both sides that this has introduced a new option, taking no existing options away. Everyone is in agreement. What situations are you thinking of that make “rare” the clarity of this distinction between threatening to injure and not threatening to injure?
And what about the variant when the winged sandal was going to be given to charity, but the Baron rushed in to prevent that, arriving just in time?
Here it’s clear that the Baron still has legal ownership (just!), but that it’s the Baron who’s changing the status quo.
You could argue that a lot of law is about specifying what the disagreement point is (generally through ownership rules and contract law), but that doesn’t mean that our legal system’s choice of disagreement point comes from any intrinsic definition that makes sense (see the difficulty with intellectual property).
I rather lost interest in the winged sandal story, but for all the attempted complications, it remains quite clear. The Countess never owned it, and the Baron wants to secure his ownership first before offering it for sale. Whatever this is, it is not blackmail. Engrossing, forestalling, regrating, badgering, or cornering), perhaps, which aren’t even illegal any more in English law.
A lot of law is about specifying exact rules. The difficulty of doing so, precisely enough to decide cases, does not imply that there is anything philosophically problematic.
Ok, try my example here:
http://lesswrong.com/r/discussion/lw/i07/semiopen_thread_blackmail/9dt9
What is the status quo there? The black car, or the green car, or just a car (colour unspecified)?
The agreement they had: an explicit stipulation of a car for £100, and a reasonable presumption on both sides that the car would be black. Agent A is breaking the contract by demanding more. This is not a difficult example.