I thought it would be interesting to answer this using a wrong method (writing the bottom line first). That is, I made an assumption about what the cost-effectiveness of grants aimed at reducing existential risk is, then calculated how much it would cost to reduce existential risk by one basis point if that cost-effectiveness was correct.
Specifically, I assumed that Ben Todd’s expectation that Long-Term Future Fund grants are 10-100x as cost-effective as Global Health and Development Fund grants is correct:
I would donate to the Long Term Future Fund over the global health fund, and would expect it to be perhaps 10-100x more cost-effective (and donating to global health is already very good).
I made the further assumptions that:
Global Health and Development Fund (GH) grants are as cost-effective as GiveWell’s top charities in expectation
Global Health grants are 8x as cost effective as GiveDirectly
GiveWell’s estimate that “donating $4,250 to a charity that’s 8x GiveDirectly is as good as saving the life of a child under five” (Ben Todd’s words) is correct.
All existential catastrophes are extinction events.
Long-Term Future Fund grants do good via reducing the probability of an extinction event in the next 100 years.
The only good counted towards Long-Term Future Fund grant cost-effectiveness is the human lives directly saved from dying in the extinction event in the next century. (The value of preserving the potential for future generations is ignored, as is the value of saving lives from any non-extinction level global catastrophic risk reduction.)
Saving the lives of people then-alive from dying in an extinction event in the next 100 years is as valuable on average as saving the life of a child under five.
If an extinction event happens in the next century, 8 billion people will die.
From these assumptions, it follows that:
Donating to the LTFF is 10-100x as cost-effective as donating to the GHDF and 80-800x as cost-effective as donating to GiveDirectly.
Donating $4,250 to the LTFF does as much good as saving the lives of 10-100 people from dying in an extinction event in the next 100 years.
Reducing the risk of human extinction in the next century by 0.01% is equivalent to saving the lives of 800,000 people.
It costs $34M-$340M (i.e. ~$100M) (donated to the LTFF) to reduce the probability of extinction in the next 100 years by 0.01% (one basis point). (Math: $4,250 * 800,000⁄100 to $4,250 * 800,000⁄10.)
To reiterate, this is not the right way to figure out how much it costs to reduce existential risk.
I worked backwards from Ben Todd’s statement of his expectations about the cost-effectiveness of grants to the LTFF, making the assumption that his cost-effectiveness estimate is correct, and further assuming that those grants are valuable only due to their effect on saving lives from dying in extinction events in the next century.
In reality, those grants may also help people from dying in non-extinction level global catastrophic risks, increasing the estimate of the cost to reduce extinction risk by one basis point. Further, there is also a lot of value in how preventing extinction preserves the potential for having future generations. If Ben Todd’s 10-100x expectation included this preserving-future-generations value, then that too would increase the estimate of the cost to reduce extinction risk by one basis point.
I thought it would be interesting to answer this using a wrong method (writing the bottom line first). That is, I made an assumption about what the cost-effectiveness of grants aimed at reducing existential risk is, then calculated how much it would cost to reduce existential risk by one basis point if that cost-effectiveness was correct.
Specifically, I assumed that Ben Todd’s expectation that Long-Term Future Fund grants are 10-100x as cost-effective as Global Health and Development Fund grants is correct:
I made the further assumptions that:
Global Health and Development Fund (GH) grants are as cost-effective as GiveWell’s top charities in expectation
Global Health grants are 8x as cost effective as GiveDirectly
GiveWell’s estimate that “donating $4,250 to a charity that’s 8x GiveDirectly is as good as saving the life of a child under five” (Ben Todd’s words) is correct.
All existential catastrophes are extinction events.
Long-Term Future Fund grants do good via reducing the probability of an extinction event in the next 100 years.
The only good counted towards Long-Term Future Fund grant cost-effectiveness is the human lives directly saved from dying in the extinction event in the next century. (The value of preserving the potential for future generations is ignored, as is the value of saving lives from any non-extinction level global catastrophic risk reduction.)
Saving the lives of people then-alive from dying in an extinction event in the next 100 years is as valuable on average as saving the life of a child under five.
If an extinction event happens in the next century, 8 billion people will die.
From these assumptions, it follows that:
Donating to the LTFF is 10-100x as cost-effective as donating to the GHDF and 80-800x as cost-effective as donating to GiveDirectly.
Donating $4,250 to the LTFF does as much good as saving the lives of 10-100 people from dying in an extinction event in the next 100 years.
Reducing the risk of human extinction in the next century by 0.01% is equivalent to saving the lives of 800,000 people.
It costs $34M-$340M (i.e. ~$100M) (donated to the LTFF) to reduce the probability of extinction in the next 100 years by 0.01% (one basis point). (Math: $4,250 * 800,000⁄100 to $4,250 * 800,000⁄10.)
To reiterate, this is not the right way to figure out how much it costs to reduce existential risk.
I worked backwards from Ben Todd’s statement of his expectations about the cost-effectiveness of grants to the LTFF, making the assumption that his cost-effectiveness estimate is correct, and further assuming that those grants are valuable only due to their effect on saving lives from dying in extinction events in the next century.
In reality, those grants may also help people from dying in non-extinction level global catastrophic risks, increasing the estimate of the cost to reduce extinction risk by one basis point. Further, there is also a lot of value in how preventing extinction preserves the potential for having future generations. If Ben Todd’s 10-100x expectation included this preserving-future-generations value, then that too would increase the estimate of the cost to reduce extinction risk by one basis point.