The following information comes from the booklet Pacifism, Socialism, Anarchism: Which Way to Peace and Justice? written by Mulford Q. Sibley and published by The War Resisters League.

To the war resister and pacifist, the central offense that can be committed by one person against another -- whether in a personal capacity or as a member of any political movement -- is to do violence. Violence, of course, denotes violation. One violates a person when one deliberately takes his or her life or injures the bodies or spirits of human beings. The Commandment against violence, the pacifist believes, is about as close to an absolute as one can discover.

This is the negative side of the pacifist statement. The positive is equally important: not only should one refrain from political or individual violence but one should also do everything possible to help create conditions and establish institutions which will discourage any form of violence.

Utah Phillips also has some really great things to say about pacifism on The Past Didn't Go Anywhere.