phys ical ▁theories ▁and ▁physical ▁or ▁natural istic ▁theories . ▁Non - phys ical ▁theories ▁hold ▁that ▁the ▁events ▁in ▁the ▁brain ▁that ▁lead ▁to ▁the ▁performance ▁of ▁actions ▁do ▁not ▁have ▁an ▁entirely ▁physical ▁explanation , ▁which ▁requires ▁that ▁the ▁world ▁is ▁not ▁closed ▁under ▁physics . ▁This ▁includes ▁interaction ist ▁dual ism , ▁which ▁claims ▁that ▁some ▁non - phys ical ▁mind , ▁will , ▁or ▁soul ▁over rides ▁physical ▁caus ality . ▁Phys ical ▁determin ism ▁implies ▁there ▁is ▁only ▁one ▁possible ▁future ▁and ▁is ▁therefore ▁not ▁compatible ▁with ▁libert arian ▁free ▁will . ▁As ▁consequ ent ▁of ▁in compat ibil ism , ▁met aph ys ical ▁libert arian ▁explan ations ▁that ▁do ▁not ▁involve ▁disp ens ing ▁with ▁physical ism ▁require ▁physical ▁ind et erm in ism , ▁such ▁as ▁probabil istic ▁sub atomic ▁particle ▁behavior   – ▁theory ▁unknown ▁to ▁many ▁of ▁the ▁early ▁writers ▁on ▁free ▁will . ▁In compat ibil ist ▁theories ▁can ▁be ▁categor ised ▁based ▁on ▁the ▁type ▁of ▁ind et erm in ism ▁they ▁require ; ▁un ca used ▁events , ▁non - det erm in ist ically ▁caused ▁events , ▁and ▁agent / subst ance - ca used ▁events . ▁ ▁Non - ca us al ▁theories ▁Non - ca us al ▁accounts ▁of ▁in compat ibil ist ▁free ▁will ▁do ▁not ▁require ▁a ▁free ▁action ▁to ▁be ▁caused ▁by ▁either ▁an ▁agent ▁or ▁a ▁physical ▁event . ▁They ▁either ▁rely ▁upon ▁a ▁world ▁that ▁is ▁not ▁caus ally ▁closed , ▁or