ive . ▁Red uct ive ▁physical ism ▁is ▁ground ed ▁in ▁the ▁idea ▁that ▁everything ▁in ▁the ▁world ▁can ▁actually ▁be ▁reduced ▁analyt ically ▁to ▁its ▁fundamental ▁physical , ▁or ▁material , ▁basis . ▁Alternatively , ▁non - re duct ive ▁physical ism ▁as ser ts ▁that ▁mental ▁properties ▁form ▁a ▁separate ▁ont ological ▁class ▁to ▁physical ▁properties : ▁that ▁mental ▁states ▁( such ▁as ▁qual ia ) ▁are ▁not ▁ont olog ically ▁redu cible ▁to ▁physical ▁states . ▁Although ▁one ▁might ▁suppose ▁that ▁mental ▁states ▁and ▁ne uro log ical ▁states ▁are ▁different ▁in ▁kind , ▁that ▁does ▁not ▁rule ▁out ▁the ▁possibility ▁that ▁mental ▁states ▁are ▁correl ated ▁with ▁ne uro log ical ▁states . ▁In ▁one ▁such ▁construction , ▁anom alous ▁mon ism , ▁mental ▁events ▁super ven e ▁on ▁physical ▁events , ▁describing ▁the ▁emer gence ▁of ▁mental ▁properties ▁correl ated ▁with ▁physical ▁properties   – ▁imp lying ▁caus al ▁redu ci b ility . ▁Non - re duct ive ▁physical ism ▁is ▁therefore ▁often ▁categor ised ▁as ▁property ▁dual ism ▁rather ▁than ▁mon ism , ▁yet ▁other ▁types ▁of ▁property ▁dual ism ▁do ▁not ▁ad here ▁to ▁the ▁caus al ▁redu ci b ility ▁of ▁mental ▁states ▁( see ▁e pi phen omen al ism ). ▁ ▁In compat ibil ism ▁requires ▁a ▁distinction ▁between ▁the ▁mental ▁and ▁the ▁physical , ▁being ▁a ▁comment ary ▁on ▁the ▁in compat ibility ▁of ▁( det erm ined ) ▁physical ▁reality ▁and ▁one ' s ▁pres umably ▁distinct ▁experience ▁of ▁will