However, in the linked post I took the numbers displayed by ACE in 2019, and scaled them back a few times to be conservative, so it would be tough to argue that they are over-optimistic. I also used conservative estimates of climate change charities to offset the climate impacts, and also toyed with using climate change charities to offset animal suffering by using the fungible welfare estimates (I didn’t post that part but it’s easy to replicate).
With a skeptical prior, multiplying by factors like this might not be enough. A charity could be 100s of times (or literally any number of times) less cost-effective than the EV without such a prior if the evidence is weak, and if there are negative effects with more robust evidence than the positive ones, these might come to dominate and turn your positive EV negative. From “Why we can’t take expected value estimates literally (even when they’re unbiased)”:
I have seen some using the EEV framework who can tell that their estimates seem too optimistic, so they make various “downward adjustments,” multiplying their EEV by apparently ad hoc figures (1%, 10%, 20%). What isn’t clear is whether the size of the adjustment they’re making has the correct relationship to (a) the weakness of the estimate itself (b) the strength of the prior (c) distance of the estimate from the prior. An example of how this approach can go astray can be seen in the “Pascal’s Mugging” analysis above: assigning one’s framework a 99.99% chance of being totally wrong may seem to be amply conservative, but in fact the proper Bayesian adjustment is much larger and leads to a completely different conclusion.
On the other hand, the more direct effects of abstaining from specific animal products rely largely on estimates of elasticities, which are much more robust.
With a skeptical prior, multiplying by factors like this might not be enough. A charity could be 100s of times (or literally any number of times) less cost-effective than the EV without such a prior if the evidence is weak, and if there are negative effects with more robust evidence than the positive ones, these might come to dominate and turn your positive EV negative. From “Why we can’t take expected value estimates literally (even when they’re unbiased)”:
On the other hand, the more direct effects of abstaining from specific animal products rely largely on estimates of elasticities, which are much more robust.