▁or ▁an ▁aspect ▁of ▁the ▁greater ▁good ▁itself . ▁This ▁principle ▁is ▁meant ▁to ▁address ▁what ▁K amm ▁feels ▁are ▁most ▁people ' s ▁considered ▁case ▁jud g ments , ▁many ▁of ▁which ▁involve ▁de ont ological ▁intu itions . ▁ ▁For ▁instance , ▁K amm ▁arg ues ▁that ▁we ▁believe ▁it ▁would ▁be ▁imper miss ible ▁to ▁kill ▁one ▁person ▁to ▁har vest ▁his ▁org ans ▁in ▁order ▁to ▁save ▁the ▁lives ▁of ▁five ▁others . ▁Yet , ▁we ▁think ▁it ▁is ▁mor ally ▁perm iss ible ▁to ▁di vert ▁a ▁run away ▁t rol ley ▁that ▁would ▁otherwise ▁kill ▁five ▁innoc ent ▁and ▁imm obile ▁people ▁onto ▁a ▁side ▁track ▁where ▁one ▁innoc ent ▁and ▁imm obile ▁person ▁will ▁be ▁killed . ▁ ▁K amm ▁bel ieves ▁the ▁Princi ple ▁of ▁Perm iss ible ▁Harm ▁explains ▁the ▁moral ▁difference ▁between ▁these ▁and ▁other ▁cases , ▁and ▁more ▁important ly ▁express es ▁a ▁constraint ▁telling ▁us ▁exactly ▁when ▁we ▁may ▁not ▁act ▁to ▁bring ▁about ▁good ▁ends — such ▁as ▁in ▁the ▁organ ▁har vest ing ▁case . ▁ ▁In ▁ 2 0 0 7 , ▁K amm ▁published ▁a ▁book ▁that ▁presents ▁new ▁theory ▁that ▁incorpor ates ▁aspects ▁of ▁her ▁" Pr inci ple ▁of ▁Perm iss ible ▁Harm ", ▁the ▁" Do ctrine ▁of ▁Product ive ▁P urity ". ▁Like ▁the ▁" Pr inci ple ▁of ▁Perm iss ible ▁Harm ", ▁the ▁" Do ctrine ▁of ▁Product ive ▁P urity " ▁is ▁an ▁attempt ▁to ▁provide ▁a ▁de ont ological