It is politicians who have to decide when to release the lockdown, and in what way. In doing so, they have to balance many considerations (as with any decision). Often the different considerations appear incommensurable so that only the roughest of judgements can be made. For example, in the case of Covid-19, one has to compare the economic benefits of releasing the lockdown with the social and psychological benefits, and then compare the total of these with the increase in deaths that would result from an early exit. We here propose a way of doing this more systematically.