An offender's desert provides a reason in favour of punishment: the state should punish those found guilty to the extent that they deserve, because they deserve it.

Theorists have distinguished ‘positive’ and ‘negative’ forms of retributivism. Positive retributivism holds that an offender’s desert provides a reason in favour of punishment; essentially, the state should punish those found guilty of criminal offences to the extent that they deserve, because they deserve it. Penal desert constitutes not just a necessary, but an in-principle sufficient reason for punishment (only in principle, however, since there are good reasons — to do with the costs, both material and moral, of punishment — why we should not even try to punish all the guilty). Negative re...