I tend to subscribe to the containment theory of justice. That is, people have free will. When they use that will to violate the liberty and property of others, a just society dictates that their ability to make harmful choices becomes contained so that they don't violate the liberty and property of other people. The containment theory implies that the violation of their will should be minimal to contain their ability to make harmful choices, but not much more. Since justice costs money, a free market tends to gravitate to minimally intrusive justice anyhow. Retribution and containment are related in the sense that sometimes the damage of poor choices can be contained with enough retribution. However, not every wrong is because somebody exercised malicious free will. Some it's just incompetence, or misunderstanding. In those cases you have a liability system, where containment isn't necessary, but disputes are resolved, and responsibility for damages upheld.

However, the purpose of the incarceration should not be retribution. It should not be deterrence.

Deterrence is different from containment. It may be a side effect of justice, as it rehabilitation, and retribution, but I think containment is the purpose of justice.