Singer thinks it would be ethically permissible to have an institution whereby beings who did not have a concept of themselves as existing over time, and did not have detailed long-term plans for the future, were brought into existence to lead happy lives and were then killed for food. Presumably this would be the case, whether the beings were human or nonhuman. (Singer has suggested that chickens or fish might be beings of the requisite kind). Singer has expressed reservations about this in the past. He has had the worry that having such an institution might encourage us to view the beings as mere commodities and slide down the slope towards what, in his view, would be genuinely unethical behaviour towards them, such as confining them or inflicting painful mutilations on them. So in "Practical Ethics" he suggested a good policy might be to adopt a general rule against using animals for food under any circumstances. But apparently he has revised this position. Obviously any institution of using animals for food that would satisfy Singer's requirements would be very different to any institution of animal agriculture that exists today. As I understand it Singer believes that for almost everyone living in developed countries today, it is pretty much impossible ethically to buy meat. While he makes some concessions to Hare's demi-vegetarian position in "Singer and his Critics", I believe his position on what the obligations of the individual living in this society are is pretty much the same as the one he took when he first wrote "Animal Liberation", in which he recommended a near-vegan diet, although with his most recent book he has also tried to make constructive suggestions to those who are not prepared to become fully vegetarian.

Another interesting argument which I have encountered on the newsgroup alt.animals.ethics.vegetarian observes that crop production harms nonhuman animals as well, and suggests that the production of some forms of grass-fed beef, with very low crop inputs, might cause no more harm to animals than the production of many vegan foods. So, given that vegans are prepared to consume foods which cause some harm such as rice, it would be irrational for them to insist that there is an obligation to boycott the grass-fed beef which causes no more harm. I don't know whether Singer has commented on this argument. I discussed the issue of collateral deaths in agriculture with him in an email and he replied "I'm a consequentialist, so I think you should minimize harm - but if the costs of avoiding a particular harm become too high (including opportunity costs which prevent you from doing other good things) then you are justified in causing the harm." In other words, yes I could drop out of the consumer society and go and live on a commune which produced food without causing any harm, thereby reducing my contribution to collateral deaths in agriculture, but that might reduce my opportunities to alleviate suffering in other ways, such as by donating to UNICEF and Oxfam. (Singer donates 20% of his income to organizations like these).

To summarize, Singer believes there is an obligation for an individual living in this society to be almost completely vegan and that any morally acceptable institution of animal agriculture would be radically different from what it is today. But he is currently taking a pragmatic approach in his effort to improve the situation and is trying to reach a larger audience. He believes it is worthwhile getting people to switch to free-range meats, as well as persuading people to go vegan.

I am not sure what I think about Singer's suggestion that it might in principle be possible to have a morally acceptable institution of using chickens for food. I incline towards the view that all sentient beings have a right to life. However, Singer is consistent and non-speciesist in drawing out the implications of his view that there is a weaker presumption against killing beings who lack a concept of themselves as an entity existing over time, and it is an interesting alternative approach that should be seriously considered.