Full Idea
It seems that killing a chimpanzee is worse than the killing of a gravely defective human who is not a person. ...[p.103] the effects on relatives of the defective human will sometimes constitute additional indirect reasons against killing the human.
Gist of Idea
Killing a chimp is worse than killing a human too defective to be a person
Source
Peter Singer (Practical Ethics [1979], 05)
Book Reference
Singer,Peter: 'Practical Ethics' [CUP 1989], p.97
A Reaction
Singer's most notorious idea. Perhaps we should all carry cards (perhaps combined with donor cards) saying how many people will care if we die.