▁libert arian ism ▁is ▁not , ▁however , ▁possible , ▁and ▁would ▁require ▁rec lass ification ▁( as ▁hard ▁in compat ibil ism ▁for ▁example , ▁given ▁that ▁the ▁universe ▁is ▁still ▁assumed ▁to ▁be ▁ind et erm in istic   – ▁although ▁the ▁classification ▁of ▁hard ▁determin ism ▁is ▁techn ically ▁valid ▁also ). ▁ ▁Mind - body ▁problem ▁ ▁The ▁idea ▁of ▁free ▁will ▁is ▁one ▁aspect ▁of ▁the ▁mind - body ▁problem , ▁that ▁is , ▁consideration ▁of ▁the ▁relation ▁between ▁mind ▁( for ▁example , ▁conscious ness , ▁memory , ▁and ▁judgment ) ▁and ▁body ▁( for ▁example , ▁the ▁human ▁brain ▁and ▁nerv ous ▁system ). ▁Philosoph ical ▁models ▁of ▁mind ▁are ▁divided ▁into ▁physical ▁and ▁non - phys ical ▁expos itions . ▁ ▁Cart esian ▁dual ism ▁holds ▁that ▁the ▁mind ▁is ▁a ▁non phys ical ▁subst ance , ▁the ▁seat ▁of ▁conscious ness ▁and ▁intelligence , ▁and ▁is ▁not ▁identical ▁with ▁physical ▁states ▁of ▁the ▁brain ▁or ▁body . ▁It ▁is ▁suggested ▁that ▁although ▁the ▁two ▁world s ▁do ▁interact , ▁each ▁retain s ▁some ▁measure ▁of ▁aut onomy . ▁Under ▁cart esian ▁dual ism ▁external ▁mind ▁is ▁responsible ▁for ▁bod ily ▁action , ▁although ▁un cons cious ▁brain ▁activity ▁is ▁often ▁caused ▁by ▁external ▁events ▁( for ▁example , ▁the ▁instant aneous ▁reaction ▁to ▁being ▁burn ed ). ▁Cart esian ▁dual ism ▁implies ▁that ▁the ▁physical ▁world ▁is ▁not ▁determin istic   – ▁and ▁in ▁which ▁external ▁mind ▁controls ▁( at ▁least ▁some ) ▁physical