Maybe I'm a grumpy old codger these days, but it seems like the thesis is "increased incarceration has lowered the crime rate outside of prisons, however inmate-on-inmate violence is appalling, therefore we should reduce incarceration". My knee-jerk reaction is "we have improved the first order problem of lower crime in society in general, creating the second-order problem where those inclined towards assault and rape are confined with others of similar mindset and continue this pattern of crime therein... shouldn't we look to preserve the desired result and simultaneously improve law and order within prisons?"

Agreed in advance that a phenomenal rate of incarceration is not the only means of reducing crime (or, as the thesis would have it, of shifting it into the inmate population) - but I'd find it hard to buy that we should turn our back on a working solution without a better one. As the article points out, 70% of released prisoners are rearrested within three years - we are largely not rehabilitating the prison population today, and fixing that would be the means I'd advocate - which would seem to also have the effect of lowering inmate-on-inmate assaults, rapes, and other violence.

I'm a bit at a loss as to why the answer would instead be a vast reduction in prison sentences (without some other substantive change making this viable)...