I think the answer as I see it to the "least harm" problem is a non-answer in the sense there is no way to refute this particular claim. Kathy and Lou above try to make the case from some overall standpoint, which of course is likely to be true. But it isn't true from an individual's point of view because it is quite possible to do less harm while eating animals, especially if we ARE worried about invertebrate pests killed by pesticides. I once calculated the number of people fed per year from two livestock farmers outputs versus crop outputs. Australia may not be the same as the US - many of our cattle are grazed on natural pasture with little supplemental feeding much of the time and don't end up in feedlots. The first farmer grazes cattle in Western Australia on marginal rangelands. He does kill some pests, but mostly kangaroos, camels and dogs. On a year's output from his farm, more people are fed per animal killed than if I were to do so from a crop of say lentils or chickpeas. In the second case, a sheep and cattle farmer from nearby my home, the lady in question runs her stock on natural pasture with some supplemental feed, mostly from local hay. In this case, more people were fed per animal killed for the crop-based diet. Both cases were fairly close, I can't recall but the difference between all diets was small. The point being that yes, you *can* consume animals and do least harm. It just depends somewhat. But in all cases, I did not count insects and rodents killed by pest management. In that case, it was far, far better to eat the meat. So, why would a vegan eat the plant food? Because we are NOT seeking to do least harm as a prime ethical directive (as Lou has pointed out before). Yet, most vegans think we are and that is what they argue, opening themselves up to criticism that they fail to adequately rebut. That is why the correct answer is a non-answer, because it's true - one can do least harm by buying meat from a farm or whatever. But that is not our main concern as vegans. It just may be a problem we have to live with.
Also, recently I spent quite a bit of time trying to unravel the "most crops are fed to animals" claim. I don't believe it to be true, not everywhere. It *might* be true in the US, it probably is not true in Australia. And certainly not in the UK. Globally, most figures seem to agree that about 30-35% of all crops grown are fed to livestock. But "fed to livestock" doesn't mean "grown to feed to livestock". In fact, a great proportion of all crops grown globally are for human use. About 60-70% (67% by one estimate), about 9% for industrial use (eg biofuels) and just 20-30% (about 24% on one estimate) are grown specifically to feed stock. So, most of the animals killed to grow crops are killed growing crops for people. It remains true however, while so long as *some* crops are fed directly to livestock, that a plants only ag system should result in fewer animals killed overall. But, again, only if the replacement system doesn't use more land to grow crops than the current system. That might be a marginal call, but I think we are on safe ground here.
The problem of discretionary foods. No-one above has actually tackled this. I think there is no good answer. IF we are only worried about "least harm" or preventing animals from being killed, then we are in the wrong whenever we buy things that we don't need but which cause other animals to suffer and die. It is difficult to see why, when Earthling Ed clearly tells us we are wrong to buy things we don't need and that each individual animal counts morally, we are doing any better than the person who eats a fish he caught because it tastes good (as per the EE video I refer to above). All that saves us, I suspect, is that we aren't really trying to do least harm but rather to prevent exploitation and that perhaps as I have suggested, we have the right to kill pests and that many pest species don't count individually, contrary to Ed's proposition. Some species don't count, end of story. But still, as compassionate people, we do hope to care about those species too, which is why I relocate house mice, don't step on ants and leave the spiders be. Nonetheless, even in this condition, it does seem strange to worry about ants and mice while I buy foods I don't need which could be causing hundreds or thousands of animals to die and globally perhaps trillions.
Sooo... I don't have great answers, and there doesn't seem to any easy succinct answers. At least, not the way I see it. Somehow, one has to be convinced of something like veganism before one can see a way clear of these charges. And even then, perhaps, one has to accept that just like everyone else, vegans do cause things to be harmed and killed, often in very large numbers. Which we all knew anyway. We just don't think it's the kind of problem that should cause us to give up seeking to do better. But... I don't think we have the kind of knock-down rebuttals that can actually defuse these charges. I am really disappointed by the "discretionary" foods one because I think it is one time where a vegan just has to go "guilty as charged". And then the non-vegan just tells you what a hypocrite you and all the other vegans are and dismisses the whole beautiful idea of veganism.
