A big source of externalities I’m not sure I’ve heard mentioned as such: people caring about one another.
For a random person, I’d guess the unaccounted for effects on other people from their making different private decisions about their lives while being cared about by numerous family and friends might be at least comparable to those from marginally contributing to air pollution or city density or traffic congestion.
Care externalities
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A big source of externalities I’m not sure I’ve heard mentioned as such: people caring about one another.
For a random person, I’d guess the unaccounted for effects on other people from their making different private decisions about their lives while being cared about by numerous family and friends might be at least comparable to those from marginally contributing to air pollution or city density or traffic congestion.