Even granting that it has some positive effect on the suffering of animals (which I've said I'm skeptical of), eliminating meat from my diet is not an unalloyed benefit to the world: it has a cost to me (inconvenience, social stigma, and so on).
So, it's possible that the net benefit of that change in my diet is negative (very small positive effect on the rest of the world, noticeable negative effect on me).
It's more like, "this action does not obviously do good, but I won't rule out that there is a bundle of actions including it that does good in aggregate".
I'm not too surprised the parent got (at least) one upvote, and I will refrain from downvoting it as I'm involved in the discussion; but I think setting up a straw-man from a bad paraphrase of your interlocutor's argument should be frowned upon.
it has some positive effect on the suffering of animals (which I've said I'm skeptical of)
If going veg indeed has negative expected utility for you, my paraphrase indeed was a wrong strawman.
I guess I found this
It's not clear to me that my deciding to switch to a purely vegetarian diet would have the consequence of preventing the suffering or delaying the death of even one animal.
hard to accept. Here's the argument against it.
I have noticed that among philosophers, vegetarianism of one form or another is quite common. In fact, I became a vegetarian (technically a pescetarian) myself partly out of respect for an undergraduate philosophy professor. I am interested in finding out if there is a similar disproportion in the Less Wrong community.
I didn't request that this go into Yvain's survey because I want more information than just what animal products you do or don't eat; I'd also like to see nuances of the reasons behind your diet. There are a lot more shades than carnivore/vegetarian/vegan - if you want to be a vegetarian but are allergic to soy and gluten, that's a compelling reason to diversify protein sources, for instance. I'd also like to hear about if you avoid any plant foods (if you think they're farmed in a way that's environmentally destructive or that hurts people or if you have warm fuzzy feelings for plants, maybe). Here are some questions that come to mind: