Decarcerate? - By JIM HOLT

If a time traveler from the future showed up in our world today, which of our practices would strike him as most barbarous? This question makes for an excellent parlor game. When we look back at supposedly civilized societies in the past, we are amazed at how complacently they accepted such obvious evils as slavery, child labor and torture. Surely, people in centuries hence will be similarly astonished at our own moral blind spots. But what might they be? After a little reflection, you may wish to hazard a guess. Here's mine: punishment by imprisonment.

Prisons happen to be one of humanity's more recent inventions. Until a couple of hundred years ago, local jails were mainly for debtors, who were held until they could arrange to have their obligations met. In England, those convicted of crimes used to be fined or whipped or branded -- a ''T'' for thieves, a ''V'' for vagrants -- or publicly humiliated by being put in a pillory, sometimes with their ears nailed to the beams. Many crimes, even minor ones, led to the gallows. Until 1820, you could be hanged for stealing as little as five shillings' worth of goods from a shop.

It was in revulsion at the cruelty of such punishments that the modern prison was created. The United States led the way. In the early 19th century, Europeans traveled to these shores to marvel at a new institution called the ''penitentiary,'' where inmates were to be reformed by a regime of silence and hard work. For a century and a half after the creation of prisons, crime dropped steadily across Western nations, even as the severity of punishment diminished. It seemed reasonable to think that as society grew more prosperous and equitable, fewer and fewer people would have to be incarcerated. more...