thisquestionisasdifficulttoanswerasouroriginalrequest
forsomerelevantfactthatjustifiestheinequalityofhumans
andotheranimals.Infact,thesetwoquestionsarereallyone:
talkofintrinsicdignityormoralworthdoesnothelp,because
anysatisfactorydefenseoftheclaimthatallandonlyhuman
beings have intrinsic dignity would needto refer to some
relevantcapacitiesorcharacteristicsthatonlyhumanbeings
have, in virtue of which they have this unique dignity or
worth.Tointroduceideasofdignityandworthasasubstitute
forotherreasonsfordistinguishinghumansandanimalsisnot
goodenough.Finephrasesarethelastresourceofthosewho
have run out of arguments.
Incaseanyonestillthinks itmaybepossible tofindsome
relevant characteristic that distinguishes all human beings
fromallmembersofotherspecies,letusconsideragainthe
factthattherearesomehumanbeingswhoquiteclearlyare
belowthelevelofawareness,self-consciousness,intelligence,
and sentienceof manynonhumanbeings.Iamthinking of
human beings with severe
and irreparable brain damage, and also of infant human
beings;toavoidthecomplicationofthepotentialofinfants,
however,Ishallconcentrateonpermanentlyandprofoundly
retarded human beings.
Philosopherswhosetouttofindacharacteristicthatwould
distinguishhumanbeingsfromotheranimalsrarelytookthe
course of abandoning these groups of human beings by
lumpingtheminwithotheranimals.Itiseasytoseewhythey
didnotdoso;totakethislinewithoutrethinkingourattitudes
tootheranimalswouldmeanwehavetherighttoperform
painfulexperimentsonretarded humansfortrivialreasons;