When Christine Smallwood ironically commented, "Then the moral position would be to let the Martians colonize Earth and make us their slaves," and Peter Singer responded, "Yes, that does seem to be the implication of the theory. A lot of people do think that's a damning objection to utilitarianism," he let her off easy.
In a less charitable mood, Singer, the author of Animal Liberation (1975), might have reminded Smallwood that we humans justify our customary slaughter of animals for food using arguments very similar to those that Smallwood's theoretical Martians would use to justify enslaving us humans. If the Martians would be wrong to do this--and if utilitarianism is wrong to provide them with moral justification to do it--then how are we to justify eating meat?
The monstrous Martian problem can be resolved, I believe, by considering a certain minimum capacity for depth of enjoyment of life to be sufficient to make killing a being with this capacity (or with any greater capacity) morally wrong. If we are generous enough to set this minimum so as to include the entire human species--and probably a few intelligent animal species as well, for the sake of consistency--then we can declare ourselves, as well as the Martians, off limits either as slaves or as food for super-intelligent space aliens.
Perhaps this solution is no longer purely utilitarian, since it seems to require that we bestow rights whose basis is a rather arbitrarily set minimum psychological capacity, which we (or the Martians) could conceivably set either higher or lower. But if this minimum includes at least the entire human species, I believe we can live with it.
Eric Paul Jacobsen
West Saint Paul, MN
Apr 28 2009 - 9:02pm