The philosophy of non-violence as the tool to effect change in a society is generally credited to Henry David Thoreau. In 1848 the United States went to war with Mexico, a war which Thoreau opposed. When he refused to pay his taxes because he did not want his money contributing to the war he was jailed. While in jail he wrote the essay Civil Disobedience, which he argued that one has a moral obligation to break laws which are immoral and unjust even if it meant going to jail. He also argued that if an individual protests using civil-disobedience (not reacting to violence, discrimination or oppression with violence but using the moral fortitude of the non-violent action as the source for change. It was Thoreau's essay Civil Disobedience that had a profound influence on Dr. Martin Luther King Jr. In essence in the 1950's it inspired Rosa Parks and the Montgomery bus boycott, the 'Little Rock Nine' at Central High School in Little Rock, Arkansas, the students who just sat until they were served at the Worthworth lunch counter. By the 1960's the 'sit-in' protests of the 1950's spilled over into the anti-war movement against the Vietnam War. The non-violent movement did have an impact upon American society, it definitely led to desegregation legislation of American society. Unfortunately, changing the laws in this country proved to be much easier than changing the mindset of some people. By the late 1960's the concept of non-violence stagnated and declined as Americans became increasingly frustrated with the war and the lack of meaning to the civil rights legislation. As a result the non-violent movement lost its luster and violence was on the rise again.
The origins of basic philosophy of non-violence can be traced back to many thousands years old concept of Ahinsa in Indian philosophy. This concept of Ahinsa was particularly emphasized in Jain and Buddhist streams of Indian philosophy. However the concept was popularized in recent times by Mahatma Gandhi during his struggle against British Rule in India from 1915 t0 1947.
The concept of non-violence as applicable to modern times refers to a method of achieving social justice by using non-violent method. Martin Luther King, a prominent practitioner of non-violence in USA has described this concept very well in his article The Meaning of Non Violence. As per King oppressed people can deal with oppression in three ways. First way is to "resign themselves to oppression". The second way is to "rise up with the violence and corroding hatred". And finally the third way is the way of non-violence. As per King:
The philosophy of non-violence contends that the means we use mus be as pure as the ends we seek. . . . one's aim must never be to inflict injury upon the opponent. In Indian Philosophy they call this idea Ahinsa - non-injury.
Non-violence as a means of securing social justice involves means such as passive-resistance and non-cooperation. It also means to to be ready to accept the punishment meted out by the oppressor in response to your non-violent methods of protest without retaliation. For example, in the famous Dandi campaign of Mahatma Gandhi, thousands of followers manufactures salt against the unjust law imposed by British. In response the police beat them up and put them in jails, but those non-violent protesters continued to break the unjust law without any violence from their side.
Many people in different countries, encouraged by the success of non-violent movement in India were encouraged to use this means to secure justice for themselves. In USA Martin Luther King adopted this method in early 1950's for his struggle against racial discrimination of African Americans, and continued to use it very successfully till his death in 1968.
A lot more information on non-violence including writings of Martin Luther King and Mahatma Gandhi can be obtained from the site Peace, Non-violence and Conflict Resolution. A link to this site is given below.