Evidence against this as an explanation: the original studies on scope insensitivity were about birds and national parks. 20,000 birds aren’t more of a threat than 200 birds, Hitchcock movies notwithstanding. Since scope insensitivity is sufficiently explained by the factors that produce it in bird and park studies, why posit extra factors to explain it on humans?
Does the bird study attempt to rule out the explanation that people are using the number of birds claimed to be saved as a cue to how many birds there are in total and so adjusting their estimate of how rare they are?
I place little to no value on the lives of individual birds but I do value the existence of some species of birds (because they are aesthetically pleasing) and I value biodiversity for both aesthetic and practical reasons. I therefore place some value on maintaining a viable breeding population of particular bird species but the marginal value of additional birds over this level is very low.
If someone asks how much I am willing to pay to save a small number of birds this is evidence that the birds are rare—the fact that someone considers it worth bringing the issue to my attention for a small number of birds suggests as much. If someone asks how much I am willing to pay to save a very large number of birds this is evidence that the birds are not rare. I would pay more to save the last 10,000 of a rare species from extinction than to save 1 billion from a population of several billion.
Fair point regarding scope insensitivity proper. But note that people are less willing to help a group of humans in need than an individual human in need. This comes through in the references on the Wikipedia page for the identifiable victim effect.
Evidence against this as an explanation: the original studies on scope insensitivity were about birds and national parks. 20,000 birds aren’t more of a threat than 200 birds, Hitchcock movies notwithstanding. Since scope insensitivity is sufficiently explained by the factors that produce it in bird and park studies, why posit extra factors to explain it on humans?
Does the bird study attempt to rule out the explanation that people are using the number of birds claimed to be saved as a cue to how many birds there are in total and so adjusting their estimate of how rare they are?
I place little to no value on the lives of individual birds but I do value the existence of some species of birds (because they are aesthetically pleasing) and I value biodiversity for both aesthetic and practical reasons. I therefore place some value on maintaining a viable breeding population of particular bird species but the marginal value of additional birds over this level is very low.
If someone asks how much I am willing to pay to save a small number of birds this is evidence that the birds are rare—the fact that someone considers it worth bringing the issue to my attention for a small number of birds suggests as much. If someone asks how much I am willing to pay to save a very large number of birds this is evidence that the birds are not rare. I would pay more to save the last 10,000 of a rare species from extinction than to save 1 billion from a population of several billion.
Good point. I voted PhilGoetz up as well when he said this.
Fair point regarding scope insensitivity proper. But note that people are less willing to help a group of humans in need than an individual human in need. This comes through in the references on the Wikipedia page for the identifiable victim effect.