[I haven't read anyone else's entries before posting this.]

My (truthful) general position: I am not vegetarian. I do think non-human animals' welfare matters. I suspect that I "should" be vegetarian in something like the sense in which I "should" give 90% of my income to charities.

Omnivore questions:

1. I think most Americans eat more meat than is optimal for their health, and I acknowledge that meat production is much less efficient in calories/dollar (or calories per litre of water, or by many other measures) than plant-food production. These facts are not necessarily even strong arguments for eating less meat (we often do things that are suboptimal by one criterion because there's something else we also care about), let alone outright vegetarianism.

2. I think much factory farming is cruel and we would probably be better off without it. There's much reason to think that happier animals' meat tastes better, too. I am happy to pay more for less cruelly produced meat. I probably would be happy to pay twice as much if (1) I had good reason to think that the cheap option really involved a lot of suffering for the animals and (2) I had good reason to think that the expensive option involved much less. I don't think any of this has much to do with being "more natural", nor with "factory farming" as such; if someone has a way of raising animals less cruelly but still in large numbers and using modern technology, that's as good morally as one that only works for small numbers and that works more traditionally. (Though maybe the latter would produce tastier meat...)

3. I can't see it ever being appropriate to farm chimpanzees, for instance. This is a matter of degree rather than a sharp dichotomy; eating animals always involves some tradeoff between the animals' interests and our own; if there's a boundary then I suppose it comes at a point where there's no possible way for the animals' meat to be so much tastier than alternatives as to justify farming and eating them. I bet that's true for chimps; it probably is for other primates; probably for whales and dolphins, too; but I don't have any very quantitative way of drawing the line.

4. If almost everyone were vegetarian, then I expect I would be vegetarian too.

Vegetarian questions:

1. I'd be absolutely OK with it in principle, but in practice I think I wouldn't want to eat it. I've got used to not eating meat, and the idea of eating anything meat-like just feels icky to me now.

2. No, I wouldn't disagree. But why should I care what's "natural"? It's natural to have a 50% chance (or whatever the right figure is) of dying in infancy. It's natural to fear anyone who looks too different from yourself. Antibiotics, telephones and charity are unnatural. Why should I do something I think is wrong just because chimpanzees do it and my long-dead ancestors did it? The final nail in the coffin of this argument is that vegetarians in fact appear to be healthier than meat-eaters. I don't think the idea that I should do something that's against my values and bad for my health because it's "natural" is credible.

3. It's my business what other people eat to about the same extent as it's my business who other people kill. I'm not, as it happens, the proselytizing sort, so I have made very little attempt to convince anyone else to stop eating meat. But I see no reason why I (or any other vegetarian) shouldn't.

4. I'm not vegetarian for the sake of my health (though that seems to be a nice side benefit) and haven't paid much attention to research on this. My understanding, which may be years out of date, is that vegetarians are less likely to be overweight and tend to have better cardiovascular health. (The health risk associated with meat-eating that I personally find most salient is parasites -- but that's just because parasites happen to freak me out, which isn't much justification for anything.)