Alas the principle “Don’t hurt unnecessarily” is not strong enough, because “necessity” is too vague: Many will argue that it is “necessary” to hurt animals so they can make more money.
What we really mean is “not necessary for human survival and health.”
Maybe “Don’t hurt if it is not vitally necessary” will resolve this ambiguity, maybe not. Competition and ambition and greed will continue to bend it in their own favor.
But please let us not make it even worse by arguing that even “necessity for human survival and health” is not strong enough.
We did not create the world, and this Darwinian world does have tragic conflicts of vital (life-or-death) interests, for example, between predator and prey.
Carnivores have no choice — but we are not carnivores, and we do have a choice. We can survive and be healthy without hurting other animals.
Vital medical research — research that really cures the sick and saves lives — is not covered even by the “Don’t hurt if it is not vitally necessary” principle.
Maybe there is some other principle. Certainly when there is any non-hurtful alternative it needs to be used. And a lot of biomedical research is just curiosity-driven (or worse), not life-saving, hence unjustifiable. And often it is far more hurtful than need be.
But I am afraid that if those who want to protect animals from unnecessary suffering push too hard on the principle that hurting is never necessary or justified, under any circumstances, they are unintentionally weakening the case for putting an end to the overwhelming proportion of the monstrous and unquestionably unnecessary hurt that is being done every day, hour, minute by the meat, dairy, egg, fish, fur, sport, pet and entertainment industries, where the only interest involved is taste, habit, supply/demand — and of course money.
Here is a thought-experiment for those animal-rights activists who are (understandably) in anguish about the scale of needless, human-inflicted animal suffering (it is a not-so-silly variant on the philosophers’ silly runaway-train thought-experiment):
You are at the helm of a train that is rapidly and unstoppably headed for a track to which your own child is tied. If you quickly throw the switch, the train will instead go to another track to which another child (unknown to you) is tied:
Do you let the train follow its course? throw the switch? toss a coin?
Even the most humane of us live in Darwin’s world, and Darwin’s world contains some unavoidable conflicts of vital (life and death) interest.
I don’t think a world in which conflicts of vital interest all have to be settled by passivity or a coin toss would be a viable one, nor a humane one.
If someone or something forcibly holds my head under water, my medulla force me to struggle furiously to breathe, even if it means trampling on my own child, and even if I would consciously rather die.
Something similar makes most social vertebrates favor their own vital interests, and (hit-and-run egg-layers excepted) those of their kin, over the vital interests of strangers, if they conflict.
In protecting the vital interests of nonhuman animals, let us not suppose ourselves capable of being holier than that. Some of us may have reached such a state, but we could never have reached it without first being ruled from birth by vital self-interest, like every other social vertebrate.
And most of us still cannot voluntarily hold our heads under water indefinitely. — So let’s not try to protect animals on the assumption that others can — or would, or should (voluntarily hold their heads under water indefinitely).
We need a principle that there is some realistic hope that most people will support. The ongoing agony is too terrible and urgent to allow holding out for an abstract idealism that there is little hope most people today will agree to.
If “Don’t hurt if it is not vitally necessary” is not strong enough, let us work to make it prevail as a first step, to end the most and the worst of the horrors. That will already make it a different world, in which to resolve the rest.