If the reason we want to track impact is to guide/assess behavior, then I think counting foreseeable/intended counterfactual impact is the right approach. I’m not bothered by the fact that we can’t add up everyone’s impact. Is there any reason that would be important to do?
In the off-chance it’s helpful, here’s some legal jargon that deals with this issue: If a result would not have occurred without Person X’s action, then Person X is the “but for” cause of the result. That is so even if the result also would not have occurred without Person Y’s action. Under these circumstances, either Person X or Person Y can (usually) be sued and held liable for the full amount of damages (although that person might be able later to sue the other and force them to share in the costs).
Because “but for” causation chains can be traced out indefinitely, we generally only hold one accountable for the reasonably foreseeable results of their actions. This limitation on liability is called “proximate cause.” So Person X proximately caused the result if their actions were the but-for cause of the result, and the result was reasonably foreseeable.
I think the policy reasons underlying this approach (to guide behavior) probably apply here as well.
I can’t find the exact term, but my casual understanding of game theory/mechanism design will point to @mhpage’s points being the right approach in economics too, not just law.
If the reason we want to track impact is to guide/assess behavior, then I think counting foreseeable/intended counterfactual impact is the right approach. I’m not bothered by the fact that we can’t add up everyone’s impact. Is there any reason that would be important to do?
In the off-chance it’s helpful, here’s some legal jargon that deals with this issue: If a result would not have occurred without Person X’s action, then Person X is the “but for” cause of the result. That is so even if the result also would not have occurred without Person Y’s action. Under these circumstances, either Person X or Person Y can (usually) be sued and held liable for the full amount of damages (although that person might be able later to sue the other and force them to share in the costs).
Because “but for” causation chains can be traced out indefinitely, we generally only hold one accountable for the reasonably foreseeable results of their actions. This limitation on liability is called “proximate cause.” So Person X proximately caused the result if their actions were the but-for cause of the result, and the result was reasonably foreseeable.
I think the policy reasons underlying this approach (to guide behavior) probably apply here as well.
I can’t find the exact term, but my casual understanding of game theory/mechanism design will point to @mhpage’s points being the right approach in economics too, not just law.