cortexthanotheranimals,thispartofthebrainisconcerned
with thinking functions rather than with basic impulses,
emotions, and feelings. These impulses, emotions, and
feelings are located in the diencephalon, which is well
developed in many other species of animals, especially
mammals and birds.^7
Wealsoknowthatthenervoussystemsofotheranimalswere
not artificiallyconstructed—asa robot mightbe artificially
constructed—to mimic the pain behavior of humans. The
nervoussystemsofanimalsevolvedasourowndid,andin
fact the evolutionary history of human beings and other
animals,especiallymammals,didnotdivergeuntilthecentral
featuresofournervoussystemswerealreadyinexistence.A
capacitytofeelpainobviouslyenhancesaspecies’prospects
ofsurvival,sinceitcausesmembersofthespeciestoavoid
sourcesof injury.Itis surelyunreasonable to supposethat
nervoussystems thatarevirtuallyidentical physiologically,
haveacommonoriginandacommonevolutionaryfunction,
and result in similar forms of behavior in similar
circumstancesshouldactuallyoperateinanentirelydifferent
manner on the level of subjective feelings.
Ithaslongbeenacceptedassoundpolicyinsciencetosearch
forthesimplestpossibleexplanationofwhateveritisweare
trying
toexplain.Occasionallyithasbeenclaimedthatitisforthis
reason“unscientific”to explainthebehaviorofanimals by
theoriesthatrefertotheanimal’sconsciousfeelings,desires,
andsoon—theideabeingthatifthebehaviorinquestioncan
beexplainedwithoutinvokingconsciousnessorfeelings,that
willbe thesimpler theory.Yet we cannowsee that such
explanations, when assessed with respect to the actual