What events, people, or causes do you consider to be the most important historical reasons that led to the decline of public executions in most societies, and shifted our behavior as human beings towards more non-violent attitudes?

Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again.