has rarely been deterrence.
Further reading:
Bentham's Panopticon is, for Foucault, an ideal architectural model of modern disciplinary power. It is a design for a prison, built so that each inmate is separated from and invisible to all the others (in separate "cells") and each inmate is always visible to a monitor situated in a central tower. Monitors will not in fact always see each inmate; the point is that they could at any time. Since inmates never know whether they are being observed, they must act as if they are always objects of observation. As a result, control is achieved more by the internal monitoring of those controlled than by heavy physical constraints.
The principle of the Panopticon can be applied not only to prisons but to any system of disciplinary power (a factory, a hospital, a school). And, in fact, although Bentham himself was never able to build it, its principle has come to pervade every aspect of modern society. It is the instrument through which modern discipline has replaced pre-modern sovereignty (kings, judges) as the fundamental power relation.
http://plato.stanford.edu/entries/foucault/#3.3A real subjection is born mechanically from a fictitious relation. So it is not necessary to use force to constrain the convict to good behaviour, the madman to calm, the worker to work, the schoolboy to application, the patient to the observation of the regulations. Bentham was surprised that panoptic institutions could be so light: there were no more bars, no more chains, no more heavy locks; all that was needed was that the separations should be clear and the openings well arranged. The heaviness of the old 'houses of security', with their fortress-like architecture, could be replaced by the simple, economic geometry of a 'house of certainty'. The efficiency of power, its constraining force have, in a sense, passed over to the other side - to the side of its surface of application. He who is subjected to a field of visibility, and who knows it, assumes responsibility for the constraints of power; he makes them play spontaneously upon himself; he inscribes in himself the power relation in which he simultaneously plays both roles; he becomes the principle of his own subjection. By this very fact, the external power may throw off its physical weight; it tends to the non-corporal; and, the more it approaches this limit, the more constant, profound and permanent are its effects: it is a perpetual victory that avoids any physical confrontation and which is always decided in advance.
<snip>
So much for the question of observation. But the Panopticon was also a laboratory; it could be used as a machine to carry out experiments, to alter behaviour, to train or correct individuals. To experiment with medicines and monitor their effects. To try out different punishments on prisoners, according to their crimes and character, and to seek the most effective ones. To teach different techniques simultaneously to the workers, to decide which is the best. To try out pedagogical experiments - and in particular to take up once again the well-debated problem of secluded education, by using orphans. One would see what would happen when, in their sixteenth or eighteenth year, they were presented with other boys or girls; one could verify whether, as Helvetius thought, anyone could learn anything; one would follow 'the genealogy of every observable idea'; one could bring up different children according to different systems of thought, making certain children believe that two and two do not make four or that the moon is a cheese, then put them together when they are twenty or twenty-five years old; one would then have discussions that would be worth a great deal more than the sermons or lectures on which so much money is spent; one would have at least an opportunity of making discoveries in the domain of metaphysics. The Panopticon is a privileged place for experiments on men, and for analysing with complete certainty the transformations that may be obtained from them. The Panopticon may even provide an apparatus for supervising its own mechanisms. In this central tower, the director may spy on all the employees that he has under his orders: nurses, doctors, foremen, teachers, warders; he will be able to judge them continuously, alter their behaviour, impose upon them the methods he thinks best; and it will even be possible to observe the director himself. An inspector arriving unexpectedly at the centre of the Panopticon will be able to judge at a glance, without anything being concealed from him, how the entire establishment is functioning. And, in any case, enclosed as he is in the middle of this architectural mechanism, is not the - 5 director's own fate entirely bound up with it ? The incompetent physician who has allowed contagion to spread, the incompetent prison governor or workshop manager will be the first victims of an epidemic or a revolt. ' "By every tie I could devise", said the master of the Panopticon, "my own fate had been bound up by me with theirs"' (Bentham, 177). The Panopticon functions as a kind of laboratory of power. Thanks to its mechanisms of observation, it gains in efficiency and in the ability to penetrate into men's behaviour; knowledge follows the advances of power, discovering new objects of knowledge over all the surfaces on which power is exercised.
http://foucault.info/documents/disciplineAndPunish/foucault.disciplineAndPunish.panOpticism.html