Peter Singer on Violence as a Means

It would be a tragic mistake if even a small section of the Animal Liberation movement were to attempt to achieve its objectives by hurting people. Some believe that people who make animals suffer deserve to have suffering inflicted upon them. I don't believe in vengeance; but even if I did, it would be a damaging distraction from our task of stopping the suffering. To do that, we must change the minds of reasonable people in our society. We may be convinced that a person who is abusing animals is entirely callous and insensitive; but we lower ourselves to that level if we physically harm or threaten physical harm to that person. Violence can only breed more violence—a cliché, but one that can be seen to be tragically true in half a dozen conflicts around the world. The strength of the case for Animal Liberation is its ethical commitment; we occupy the moral high ground and to abandon it is to play into the hands of those who oppose us.

(Peter Singer, Animal Liberation, 2d ed. [New York: The New York Review of Books, 1990], xii-xiii)