This is Holden Karnofsky, the co-Executive Director of GiveWell, which is referenced in the top-level article and elsewhere on this thread.
I think there is an important difference between discussing the marginal impact of a blood donation and the marginal impact of a vote. When it comes to blood donations, it is possible for everyone to simultaneously follow the rule: “Give blood only when the supply of donations is low enough that an additional donation would have high expected impact”, with a reasonable outcome. It is not possible for everyone to behave this way in elections: no voter is able to consider the existing distribution of votes before casting their own.
I am only casually familiar with TDT/UDT, but it seems to me that that “Give blood only when the supply of donations is low enough that an additional donation would have high expected impact” should get about the same amount of credit under TDT/UDT as giving blood, and thus the extra impact of actually giving blood (as opposed to following that rule) is small regardless of what decision theory one is using.
I bring this up because the discussion of marginal blood donations is parallel to analysis GiveWell often does of the marginal impact of donations. We do everything we can to understand the marginal (not average) impact of a donation and recommend organizations on this basis, and we believe this is a very important and unique element of what we offer (more on this issue). We try to push donors to underfunded charities and away from overfunded ones, and I do not think the validity of this depends on any controversial (even controversial-within-Less-Wrong) view on decision theory, though I am open to arguments that it does.
Completely agree with your general point on marginal analysis (although I’m a TDT skeptic), and am a fan of GiveWell, but this is trivially wrong:
It is not possible for everyone to behave this way in elections: no voter is able to consider the existing distribution of votes before casting their own.
This seems to assume away information about the size of the electorate as well as any predictive power about the outcome. Surely the marginal benefit of a Presidential vote in a small swing state is massively higher than in a large solidly Democratic state, for example. And in addition to historical results, there is polling data in advance of the election to improve predictions.
Besides this being theoretically true, we can see it empirically from the spending patterns of both Presidential campaigns and political parties on Congressional races. They allocate money to the states / races where they believe it will do the most marginal good, which is often a very inequal distribution. Thus they do, in fact “consider the existing distribution of votes before casting” their advertising dollars.
Patrissimo, fair enough. I was thinking that voters can’t vote with the same degree of knowledge of the existing situation that they can have with blood donations. Arguments over TDT certainly seem more relevant to voting than to blood donations. But you are right that voters have lots of relevant information about the likely distribution of votes that can be productively factored into their decisions regardless of the TDT debate. Glad to hear you’re a fan of GiveWell.
This is Holden Karnofsky, the co-Executive Director of GiveWell, which is referenced in the top-level article and elsewhere on this thread.
I think there is an important difference between discussing the marginal impact of a blood donation and the marginal impact of a vote. When it comes to blood donations, it is possible for everyone to simultaneously follow the rule: “Give blood only when the supply of donations is low enough that an additional donation would have high expected impact”, with a reasonable outcome. It is not possible for everyone to behave this way in elections: no voter is able to consider the existing distribution of votes before casting their own.
I am only casually familiar with TDT/UDT, but it seems to me that that “Give blood only when the supply of donations is low enough that an additional donation would have high expected impact” should get about the same amount of credit under TDT/UDT as giving blood, and thus the extra impact of actually giving blood (as opposed to following that rule) is small regardless of what decision theory one is using.
I bring this up because the discussion of marginal blood donations is parallel to analysis GiveWell often does of the marginal impact of donations. We do everything we can to understand the marginal (not average) impact of a donation and recommend organizations on this basis, and we believe this is a very important and unique element of what we offer (more on this issue). We try to push donors to underfunded charities and away from overfunded ones, and I do not think the validity of this depends on any controversial (even controversial-within-Less-Wrong) view on decision theory, though I am open to arguments that it does.
Completely agree with your general point on marginal analysis (although I’m a TDT skeptic), and am a fan of GiveWell, but this is trivially wrong:
This seems to assume away information about the size of the electorate as well as any predictive power about the outcome. Surely the marginal benefit of a Presidential vote in a small swing state is massively higher than in a large solidly Democratic state, for example. And in addition to historical results, there is polling data in advance of the election to improve predictions.
Besides this being theoretically true, we can see it empirically from the spending patterns of both Presidential campaigns and political parties on Congressional races. They allocate money to the states / races where they believe it will do the most marginal good, which is often a very inequal distribution. Thus they do, in fact “consider the existing distribution of votes before casting” their advertising dollars.
Patrissimo, fair enough. I was thinking that voters can’t vote with the same degree of knowledge of the existing situation that they can have with blood donations. Arguments over TDT certainly seem more relevant to voting than to blood donations. But you are right that voters have lots of relevant information about the likely distribution of votes that can be productively factored into their decisions regardless of the TDT debate. Glad to hear you’re a fan of GiveWell.