Lewis on retribution, revenge, and mercy

 For Lewis punishment is about retribution,  which is different from revenge. Revenge is not limited by what someone deserves, and typically when people take revenge, the do more to them than what they did to the other person. When you give someone what they deserve, you can't hurt them more than they deserve, and Lewis is open to saying that courts can be merciful and, for a good reason, give people less than they deserve. 

See here. 

Two Australian penologists responded, here, as did Australian philosopher J. J. C. Smart, here, who in spite of famously becoming an act utilitarian, seems to have been a rule utilitarian at this point. Lewis responded here. 

Utilitarianism, life, and death

A redated post. 

An implication of utilitarianism that I have never heard discussed much is that pain turns out to be a fate worse than death, according to it. If the calculus attempts to determine what is right based on whether something produces the best balance of pleasure over pain, who is or is not dead seems not to count. Death is just a way of going to zero: no pain and no pleasure either. If you are a utilitarian and you know how to put people out of their misery painlessly, maybe a career as a serial killer is morally obligatory for you.

A possible utilitarian reply to Nozick's Ultimate Pleasure Machine objection to utilitarianism

A utilitarian might reply that most people who aim at pleasure aim at their own pleasure. But when we aim at everyone's pleasure instead of just our own, we don't find the unfulfilling situation that we find with the "ultimate pleasure machine."

I have linked to a discussion of the Ultimate Pleasure Machine on Free Cognition.

More on slavery and utilitarianism

It could well be that, looking at it over time (when there were no machines to be our slaves) it could be argued that slavery resulted in an overall positive balance of pleasure over pain. The game changed with the development of industrialization, when we could switch to machines as a source of physical energy.

A general rejection of slavery might have to be based on something else than utility.

Slavery and Utilitarianism

Let's say that we figure out a plan for enslaving 10% of the population. If we do that, then each of the other 90% will receive 10 units of happiness that they would not otherwise have. The slave will, of course, lose 50 units of happiness. However, 10 units of happiness spread of 9 people is 90 units of additional happiness, which outweighs the 50 units of happiness lost by the slave. Therefore, based on utilitarianism, we have a justification for slavery.

Now, these calculations aren't accurate. But we are left with this question: is this the real reason that we oppose slavery. Because the pain of the slaves outweighs the pleasure of the masters? If utilitarianism is correct, then that must be our reason.