IN the primitive stages of ethical thought, 'collective guilt' was the norm: the fault of one was imputed to his whole clan or tribe. Vengeance could then be exacted on any and all of its members. It was also believed that sin was inherited like some genetic mutation is, so that in some parts of the Old Testament, we have God warning about punishment to the third and fourth generation — quite a distance from the offender, but liable to penalty nonetheless.