Coercion is the practice of forcing another party to act in an involuntary manner by use of threats or force. It involves a set of various types of forceful actions that violate the free will of an individual to induce a desired response, for example: a bully demanding lunch money from a student or the student gets beaten. These actions may include extortion, blackmail, torture, threats to induce favors, or even sexual assault. In law, coercion is codified as a duress crime. Such actions are used as leverage, to force the victim to act in a way contrary to their own interests. Coercion may involve the actual infliction of physical pain/injury or psychological harm in order to enhance the credibility of a threat. The threat of further harm may lead to the cooperation or obedience of the person being coerced.
Various forms of coercion are distinguished: first on the basis of the kind of injury threatened, second according to its aims and scope, and finally according to its effects, from which its legal, social, and ethical implications mostly depend.
Physical coercion is the most commonly considered form of coercion, where the content of the conditional threat is the use of force against a victim, their relatives or property. An often used example is "putting a gun to someone's head" (at gunpoint) or putting a "knife under the throat" (at knifepoint or cut-throat) to compel action or the victim gets killed or injured. These are so common that they are also used as metaphors for other forms of coercion.
Armed forces in many countries use firing squads to maintain discipline and intimidate the masses, or opposition, into submission or silent compliance. However, there also are nonphysical forms of coercion, where the threatened injury does not immediately imply the use of force. Byman and Waxman (2000) define coercion as "the use of threatened force, including the limited use of actual force to back up the threat, to induce an adversary to behave differently than it otherwise would." Coercion does not in many cases amount to destruction of property or life since compliance is the goal.
In psychological coercion, the threatened injury regards the victim's relationships with other people. The most obvious example is blackmail, where the threat consists of the dissemination of damaging information. However, many other types are possible e.g. so-called "emotional blackmail", which typically involves threats of rejection from or disapproval by a peer-group, or creating feelings of guilt/obligation via a display of anger or hurt by someone whom the victim loves or respects. Another example is coercive persuasion.
Psychological coercion - along with the other varieties - was extensively and systematically used by the government of the People's Republic of China during the "Thought Reform" campaign of 1951-1952. The process - carried out partly at "revolutionary universities" and partly within prisons - was investigated and reported upon by Robert Jay Lifton, then Research Professor of Psychiatry at Yale University: see Lifton (1961). The techniques used by the Chinese authorities included a technique derived from standard group psychotherapy, which was aimed at forcing the victims (who were generally intellectuals) to produce detailed and sincere ideological "confessions". For instance, a professor of formal logic called Chin Yueh-lin - who was then regarded as China's leading authority on his subject - was induced to write: "The new philosophy [of Marxism-Leninism], being scientific, is the supreme truth" [Lifton (1961) p. 545].