As a first-pass model: removing person-years from the present doesn’t reduce the number of animals harmed before a solution is found; it just makes the solution arrive later.
I doubt that is a good way to model this (for farmed animals). Consider the extremes:
If we reduce the human population size to 0, we reduce the amount of suffering of farmed animals to zero, since there will be no more farmed animals
If we increase the human population to the Malthusian limit, we increase the amount of suffering of farmed animals in the short and probably medium terms, and may or may not decrease farmed animal suffering in the longer term. One reason to think we would increase the amount of suffering by adding many more people is that, historically, farmed animal suffering and human population have likely been closely correlated. At any rate, the amount of farmed animal suffering in this scenario is likely nonzero.
So as a first approximation, we should just assume the amount of suffering in factory farms increases monotonically with the human population, since we can be fairly confident in these three data points (no suffering with no humans; lots of suffering with 8B humans; maybe more, maybe less suffering at the Malthusian limit). Of course that would be an oversimplified model. But it is a starting point, and to get from that starting point to “adding people on the margin reduces or doesn’t affect expected farmed animal suffering” needs a better argument.
Basically, yes, assume that meat eating increases with the size of human population. But the scientific effort towards ending the need to meat eat also increases with the size of the human population, assuming marginal extra people are as equally likely to go into researching the problem as the average person. Under a simple model the two exactly balance out, as you can see in the spreadsheet.
I just think real life breaks the simple model in ways I have described below, in a way that preserves a meat-eater problem.
Yeah, but as you point out below, that simple model makes some unrealistic assumptions (e.g., that a solution will definitely be found that fully eliminates farmed animal suffering, and that a person starts contributing, in expectation, to solving meat eating at age 0). So it still seems to me that a better argument is needed to shift the prior.
I doubt that is a good way to model this (for farmed animals). Consider the extremes:
If we reduce the human population size to 0, we reduce the amount of suffering of farmed animals to zero, since there will be no more farmed animals
If we increase the human population to the Malthusian limit, we increase the amount of suffering of farmed animals in the short and probably medium terms, and may or may not decrease farmed animal suffering in the longer term. One reason to think we would increase the amount of suffering by adding many more people is that, historically, farmed animal suffering and human population have likely been closely correlated. At any rate, the amount of farmed animal suffering in this scenario is likely nonzero.
So as a first approximation, we should just assume the amount of suffering in factory farms increases monotonically with the human population, since we can be fairly confident in these three data points (no suffering with no humans; lots of suffering with 8B humans; maybe more, maybe less suffering at the Malthusian limit). Of course that would be an oversimplified model. But it is a starting point, and to get from that starting point to “adding people on the margin reduces or doesn’t affect expected farmed animal suffering” needs a better argument.
I think Richard is right about the general case. It was a bit unintuitive to me until I ran the numbers in a spreadsheet, which you can see here:
https://docs.google.com/spreadsheets/d/1pRW3WinG1gzJM3RER2Q4Tl5kscJRESuG8qupHGN1Wnw/edit?usp=drivesdk
Basically, yes, assume that meat eating increases with the size of human population. But the scientific effort towards ending the need to meat eat also increases with the size of the human population, assuming marginal extra people are as equally likely to go into researching the problem as the average person. Under a simple model the two exactly balance out, as you can see in the spreadsheet.
I just think real life breaks the simple model in ways I have described below, in a way that preserves a meat-eater problem.
Yeah, but as you point out below, that simple model makes some unrealistic assumptions (e.g., that a solution will definitely be found that fully eliminates farmed animal suffering, and that a person starts contributing, in expectation, to solving meat eating at age 0). So it still seems to me that a better argument is needed to shift the prior.
Fair enough.
My central expectation is that value of one more human life created is roughly about even with the amount of nonhuman suffering that life would cause (based on here https://forum.effectivealtruism.org/posts/eomJTLnuhHAJ2KcjW/comparison-between-the-hedonic-utility-of-human-life-and#Poultry_living_time_per_capita). I’m also willing to assume cultured meat is not too long away. Then the childhood delay til contribution only makes a fractional difference and I tip very slightly back into the pro natalist camp, while still accepting that the meat eater problem is relevant.