The question is often posed in informal discussions and ethical forums: Is it forbidden to purchase products that were produced due to animal suffering, such as cosmetics tested on animal?

Animals have always been an important part of human existence; from the dawn of history until only a few generations ago, virtually every person from the poorest to the richest lived in the intimate company of domestic animals. So it is hardly surprising that the Torah devotes much attention to the place of animals in creation and to their relationship with mankind.

Following the creation of mankind, the first thing God does is to define his place in creation. First we learn that only man is created in God's image, and is given "dominion over the fish of the sea, the birds of the air, and every living thing that creeps upon the earth" (Genesis 1:26).

Adam seeks companionship among the animals, but finds it only with Eve.

Later, God sees that Adam needs companionship (Genesis 2:18). Adam seeks this companionship among the animals, but finds it only with Eve, a human companion. Again we see that animals are in some sense kindred spirits to man, but not equals.

As mankind's holy mission is cemented with the giving of the Torah at Mount Sinai, the thical treatment of animals is discussed in a variety of contexts:

• The Torah declares: "Six days shall you do your tasks and on the seventh day rest, in order that your ox and donkey shall rest…" (Exodus 23:12)

• In Exodus 23:5, we find: "If you see [even] your enemy's donkey struggling under a load, don't refrain from helping him; surely help him [to unload]." According to the Talmud (Bava Metzia 31a), this is one source for the prohibition of animal suffering.

• Deuteronomy 12:21 describes the commandment to slaughter animals before eating them. Many commentators, including Sefer Hachinuch, explain that one purpose of this command is that kosher slaughter is a humane way of killing, causing only minimal suffering to the animal.

• Deuteronomy 22:6-7 is the commandment to send away the mother bird before taking the eggs for our own use. The commentators explain that seeing the eggs taken away causes distress to the mother, which is partially alleviated by sending her away.

• Deuteronomy 22:9 is the prohibition against plowing with two different kinds of animals. The Sefer Hachinuch suggests that plowing with animals of different species causes distress to one another.

• Deuteronomy 25:4 declares: "Don't muzzle the ox as it threshes." Again the Chinuch explains that it is stressful for an animal to be surrounded by food, yet unable to eat.

One thing we notice from these commandments is that they go far beyond merely avoiding active cruelty to animals. In most cases the commandment is to take positive action to alleviate distress.

Ethical obligations to animals are commensurate with the benefit they provide.

Another thing we notice is that commandments are ultimately limited in scope. Only animals belonging to a Jew, who himself is commanded to keep the Sabbath, needs to rest on Shabbat. Kosher slaughter is a requirement only when the animal is to be eaten, but not for example if it is needed for leather. While we many not plow with two species together, there is no requirement to refrain from putting an animal to hard labor.

I believe that these two aspects are related. Ethical obligations to animals are commensurate with the benefit they provide us, and our relationship with them. Animals that work for us all week long rest on Shabbat; animals that help with our loads should be helped when they are overburdened; animals which provide us with vital sustenance need to be slaughtered in a humane fashion.

Cruelty is of course forbidden towards any creature, but the higher levels of obligation are commensurate with the degree of connection with and benefit from the animal.

This answers what some people consider a paradox of the Jewish approach to animals: If Judaism acknowledges ethical duties toward animals, why does it allow us use them for our benefit? In fact, the duties to animals are a consequence of the benefit we derive from them. Ethical duties don't arise in a vacuum; they generally stem from a combination of empathy and reciprocity. Reciprocity doesn't have to mean tit for tat; animals won't go on strike and refuse to help if some people treat them cruelly. In this context, reciprocity means that we acknowledge the benefit animals provide, and requite it with basic standards of humane treatment.

Resolving the Paradox

There is still a bit of a paradox, however. We are not allowed to cause suffering gratuitously to any animal, but if there is a valid human need then even if the animal will suffer the treatment is not considered cruelty. For this reason, it is permissible and proper to use animals in medical experiments that are expected to lead to treatments that will alleviate human suffering. But this very usefulness is also what cements our obligation to show concern for the animals.

While the prohibition on animal suffering would never forbid using animals for an important human need (even if the use involved animal suffering), it would forbid causing unnecessary suffering for that need. Nachmanides writes (Deut. 22:6), "[God's] mercy on creatures with an animal soul does not extend to prevent us from using them for our needs."

Human treatment of animals cultivates humane conduct toward people.

This standard seems to be stricter than the standard for bal tashchit, which forbids gratuitous harm to or destruction of anything valuable or useful to humans. Regarding bal tashchit only gratuitous harm is forbidden, but tzaar baalei chaim, the prohibition on animal suffering, would seem to forbid also disproportionate suffering. The Talmudic sage Rabbi Pinchas ben Yair states that hamstringing an animal would constitute forbidden suffering, but only killing it would constitute gratuitous harm. My interpretation is that hamstringing the animal does bring some benefit, but not enough to justify the suffering induced. (Talmud - Chullin 7b)

An additional reason mentioned by the Sages for human treatment of animals is that it cultivates humane conduct toward other people, while inhumane treatment of animals carries the danger of inculcating insensitivity toward others. (Research confirms a connection between people who torture animals as youngsters and those who are violent as adults, though there is no way to tell if there is a causal relationship.)

The Sefer Hachinuch (596) writes: "Among the motivations for this commandment is to accustom ourselves to delicate souls, choosing the straight path and adhering to it, and seeking mercy and kindness. Once we obtain this habit, then even toward animals, which were created to serve us, we will show concern."

And Nachmanides writes: "The reason for refraining [from taking the eggs in the presence of the mother] is to teach us the quality of mercy, and not to act cruelty. For cruelty [toward animals then] spreads into the soul of man [and expresses itself toward people as well]."