To begin with, one should note that incarceration has not always been a common form of punishment. Corporal punishment, forced labor, and social ostracism were far more common forms of punishment than incarceration in the ancient world, medieval Europe, and even in England and colonial America. This changed with the 18th Century enlightenment in France and England, which gave rise to new views on liberty, human nature and time. The birth of incarceration as punishment (rather than as detention or for security) was the concept that restricting a person's liberty would itself be significant retribution for crime, and that a measured amount of time served could be assigned in proportion to the severity of the crime. In the United States this enlightenment concept was combined with the early American colonies' deeply religious worldview, which went to the extent of treating biblical crimes such as blasphemy as legal violations, to make modern prisons. American prisons are a unique institution with a roughly two hundred year history of inhumanity followed by well-meaning but short-lived attempts at reform.
The first prisons in the independent United States were established as "penitentiaries" to denote their prisoners as religious "penitents," serving time for their sins. Early penitentiaries gained national and international attention for their high goals of perfecting society through incarceration, but despite their high moral aims, they soon became as overcrowded, dirty, and dangerous earlier European dungeons. Maintaining control of their populations became their primary task.
By the late 19th Century, outrage over prison conditions led to the "reformatory" movement, which attempted to redefine prison's role as that of "reforming" inmates into model citizens, by providing education, work, and counseling. Innovative flexible-time sentences (e.g. "four to seven years") indicated that reform was a variable process, and could be completed sooner or later depending on the individual prisoner. Children were separated out from adult prisoners for the first time, although so little accountability was built into early juvenile-justice systems that conditions rapidly became far worse than those for adults. And again, despite the curricula and activities of the reformatory movement, prison conditions deteriorated to a struggle for control in inhumane and hostile conditions.
