While many people in the effective altruism movement are vegan, I'm not, and I wanted to write some about why. The short answer is what while I'm on board with the general idea of making sacrifices to help others I think veganism doesn't represent a very good tradeoff, and I think we should put our altruistic efforts elsewhere.

There are many reasons people decide to eat vegan food, from ethics to taste to health, and I'm just interested in the ethical perspective. As a consequentialist, the way I see this is, how would the world be different if I stopped eating animals and animal products?

One factor is that I wouldn't be buying animal products anymore, which would reduce the demand for animals, and correspondingly the amount supplied. Elasticity means that if I decrease by buying by one unit I expect production to fall by less than one unit, but I'm going to ignore that here to be on the safe side. Peter Hurford gives a very rough set of numbers for how many animals continuously living are required to support a standard American diet and gets:

• 1/8 of a cow
• 1/8 of a pig
• 3 chickens
• 3 fish

For example, a typical American consumes about a quarter of a pig per year, and these pigs live about six months, so that's 1/8 of a pig on an ongoing basis. I haven't checked his numbers in detail, but there are 78M pigs and 327M people in the US, so one pig for every four people, and once you consider that we export a lot of pork this seems in the right range.

Now, I don't think animals matter as much as humans. I think there's a very large chance they don't matter at all, and that there's just no one inside to suffer, but to be safe I'll assume they do. If animals do matter, I think they still matter substantially less than humans, so if we're going to compare our altruistic options we need a rough exchange rate between animal and human experience. Conditional on animals mattering, averting how many animal-years on a factory farm do I see as being about as good as giving a human another year of life?

• Pigs: about 100. Conditions for pigs are very bad, though I still think humans matter a lot more.
• Chickens: about 1,000. They probably matter much less than pigs.
• Cows: about 10,000. They probably matter about the same as pigs, but their conditions are far better.
• Fish: about 100,000. They matter much less than chickens.

These are very rough, and this is the main place where I think I differ from most ethical vegans: I think humans matter much more than these animals. Your own views may also be different!

Overall this has, to my own personal best guess, giving a person another year of life being more valuable than at least 230 Americans going vegan for a year.

The last time I wrote about this I used $100 as how much it costs to give someone an extra year of life through a donation to GiveWell's top charities, and while I haven't looked into it again that still seems about right. I think it's likely that you can do much better than this through donations aimed at reducing the risk of human extinction, but is a good figure for comparison. This means I'd rather see someone donate $43 to GiveWell's top charities than see 100 people go vegan for a year.

Since I get much more than $0.43 of enjoyment out of a year's worth of eating animal products, veganism looks like a really bad altruistic tradeoff to me.