An idea does not become an action unless the individual actor believes that the idea is worth acting on.

That's a sentence from this article.  Here's the end of that paragraph:

To subjugate another human being, or to condone or allow the subjugation of one by another, one must first have the idea of subjugation and must believe that acting on it is preferable to ignoring or condemning it. Scarcity and natural death need no such human consent. The old saying about death and taxes turns out to be only half true.

Here's another good quote:

The Chinese army fired on their fellow citizens in Tiananmen Square. This massacre was not caused by political leaders and generals saying, “Shoot”; but by men in the Chinese army deciding to shoot. It was not caused ultimately by bad leadership, but by a belief in the necessity of obeying orders. There will always be people with a will to power; a desire to control. Only when the rest don’t believe that power to be necessary and therefore do not obey does freedom reign.