Pacificism is the general ethical opposition to war

War

War is a state of organized, armed, and often prolonged conflict carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. War should be understood as an actual, intentional and widespread armed conflict between political...

 or violence

Violence

Violence is the use of physical force to apply a state to others contrary to their wishes. violence, while often a stand-alone issue, is often the culmination of other kinds of conflict, e.g...

, except in cases where force is deemed absolutely necessary to advance the cause of peace

Peace

Peace is a state of harmony characterized by the lack of violent conflict. Commonly understood as the absence of hostility, peace also suggests the existence of healthy or newly healed interpersonal or international relationships, prosperity in matters of social or economic welfare, the...

.

It falls between pacifism

Pacifism

Pacifism is the opposition to war and violence. The term "pacifism" was coined by the French peace campaignerÉmile Arnaud and adopted by other peace activists at the tenth Universal Peace Congress inGlasgow in 1901.- Definition :...

, which usually states that violence, war or killing is unconditionally wrong in all cases, and defensivism

Defensivism

Defensivism is a philosophical standpoint related in spirit to the Non-aggression principle. It is also a midway point between other combat-based philosophies, that of Just War and Pacifism....

, which accepts all defensive wars and acts of deterrence as morally just. Pacificism states that war can only ever be considered as a firm "last resort", condemning both aggression

Aggression

In psychology, as well as other social and behavioral sciences, aggression refers to behavior between members of the same species that is intended to cause humiliation, pain, or harm. Ferguson and Beaver defined aggressive behavior as "Behavior which is intended to increase the social dominance of...

 and militarism

Militarism

Militarism is defined as: the belief or desire of a government or people that a country should maintain a strong military capability and be prepared to use it aggressively to defend or promote national interests....

.

The theory was first put forward by A. J. P. Taylor

A. J. P. Taylor

Alan John Percivale Taylor, FBA was a British historian of the 20th century and renowned academic who became well known to millions through his popular television lectures.-Early life:...

 in The Trouble-Makers and was subsequently defined by Martin Ceadel in his 1987 book, Thinking About Peace and War. It was also discussed in detail in Richard Norman

Richard Norman

Professor Richard J. Norman, BA , PhD , is a British academic, philosopher and humanist. He is currently Emeritus Professor of Moral Philosophy at the University of Kent, and Vice-President of the British Humanist Association....

's book: Ethics, Killing and War.

The largest national peace association in history, the British League of Nations Union

League of Nations Union

The League of Nations Union was an organization formed in the United Kingdom to promote international justice, collective security and a permanent peace between nations based upon the ideals of the League of Nations. The League of Nations was established by the Great Powers as part of the Paris...

, was pacificist rather than pacifist in orientation. Historically, the majority of peace activists have been pacificists rather than strict pacifists.