In this column, I try to maintain a balance between issues of particular current interest and more theoretical issues of long-term interest. In response to some recent queries I want to return this week to a theoretical question of constant practical importance: animal welfare. Even if we accept that humans have an ethical obligation to consider the well-being of animals, there can be significant disagreement on how that well-being is defined. After studying this question for some time, I find a significant philosophical weakness in the approach of many animal rights groups. Years ago it occurred to me that widespread eschewing of animal products, besides being detrimental to human well-being, would be an even greater disaster for animal well-being. Why do I think it would be detrimental to human well-being? Well here's a topical example: Just a few weeks ago two Georgia parents were convicted of murder after their infant child, whom they fed a vegan diet (no animal products), died of malnutrition. Maintaining health on a vegan diet is certainly possible, but it requires immense education and planning and is not something really suitable for the unwashed masses of our species. Why a disaster for animal well-being? It would mean almost complete destruction of some of the most populous species of animals in existence. According to the UN, Earth is home to about four billion livestock (four-footed domestic food species, mainly cattle, hogs and sheep) and about twenty billion poultry (mostly chickens); if humans didn't use these animals for food and to a lesser extent apparel, their populations would be a few million at most. I often imagine that if animals were aware of this threat, they would organize a protest march against the more extreme "animal rights" groups. At any rate, I was not surprised to discover that I did not originate this line of thought; it was given a succinct expression by 19th century reformer Henry George: "Both the jayhawk and the man eat chickens, but the more jayhawks, the fewer chickens, while the more men, the more chickens." I give great credit for intellectual honesty to the leading animal rights/animal welfare Web sites, which do not evade this argument and indeed give it a considered philosophical discussion. I just find that their responses are weak and unconvincing. At animal-rights.com, this question is addressed by DG (I cannot find a full name). DG acknowledges that "animal rights" differ from "human rights" based on differing capacities and desires: "Although there is a basis for speaking of animals as having rights, that does not imply or require that they possess all the rights that humans possess... Since animals lack the capacity to rationally consider actions and their implications, and to understand the concept of democracy and voting, they lack the capacity to vote. There is, therefore, no ethical imperative to allow them to do so." DG then considers the specific argument I raise - that animal populations would collapse without human omnivores. The somewhat involved reply is basically an elaboration of the statement that "It is better not to be born than to be born into a life of misery and early death." It is exactly this statement that I would challenge regarding animals. Indeed, even regarding people the answer is far from obvious, and the Talmud tells us that students of the ancient Jewish sages Hillel and Shamai argued thousands of years ago whether it is a privilege or a burden to be born. For animals, I think that the success and population of the species is foremost in the relevant ethical calculus. From a philosophical point of view, Jewish thought tends to the position that animal welfare is weighed primarily at the level of the species, rather than the level of the individual. (This idea is developed at length in Maimonides's "Guide.") From a behavioral perspective, we see that animals will go to any length of suffering and sacrifice in order to reproduce. And since an evolutionary perspective considers reproductive success the unique standard of species achievement, it would certainly consider being useful to man the key to success for any species. In DG's terminology, I would liken the right to be free from human exploitation to the right to vote: something that is very important for humans but not directly applicable to animal standards of well-being. This doesn't mean that there is no relevant trade-off between individual animal welfare and overall animal population, and in past columns I have made the case that animal suffering is a worthy ethical concern. Many animal welfare groups make well-defended arguments that relatively simple reforms can greatly reduce animal suffering at little cost in human welfare. However, the more extreme "animal rights" position, that animals have an inherent right to be free from human-imposed suffering, seems to me based on an unconvincing and indeed mistaken understanding of the essence of animal well-being, and would lead to greatly diminished welfare for humans and domestic animals alike. firstname.lastname@example.org The writer is research director at the Business Ethics Center of Jerusalem (www.besr.org), an independent institute in the Jerusalem College of Technology.