During his talk, while explaining that there can be a legal order without a state creating it, Tom fielded a question from a student who raised the problem of witch hunts happening in a customary legal system. (He used Arthur Miller's Crucible as a case in point). He pointed out that customary legal orders tend to evolve.
However this also raises another point, of enormous importance. Basically, witch hunts are a result of state law, above all of the existence of a seperate and distinct criminal justice system as a part of the legal system. In customary legal orders (as Tom explained) there is no real distinction between crimes and torts. Essentially there are offences, which are all handled by the same procedure and result in the same outcome, that of the payment of compensation or restitution to the injured party. In a criminal justice system those found guilty typically face punishments that are frequently both severe and irreversible. Consequently the CJS operates in a different way to the rest of the legal system. Above all it has a much higher standard of proof and procedures that give the advantage to the defendant, on the basis that to wrongly punish somebody is so bad that "better a hundred guilty go free than one innocent person be convicted". One consequence is that for some kinds of crime (typically those that by their nature are not seen by third parties ) it is typically difficult to prove the guilt of the accused person in a court of law. This becomes a real problem when the crime involved is one that is generally regarded as particularly egregious. Witchcraft, subversive beliefs or heresy, child abuse and rape are all examples of this. One solution is to take it on the chin and accept that many perpetrators of such crimes will inevitably escape punishment because of the difficulty of establishing guilt. Often however people (for good reasons) are unwilling to accept this. The other solution is to change the procedures of the cjs so as to weaken the rights of defendants. Above all it frequently leads to reliance upon confessions, even if extracted by duress. What then happens in many cases is that these confessions incriminate others and the result is a cascade of charges, leading to panic, mass trials and the other features of a witch hunt, literal or metaphorical.
This happens because of one of the central features of the state legal order, the existence of a distinct criminal justice system. As things are we face an unpalatable choice. We can let people who have committed atrocious crimes escape in large numbers or we can tweak the cjs in ways that will lead to witch hunts and frequent wrongful convictions, with catastrophic results for those involved. The way to cut this Gordian knot is to handle such cases as torts with a lower standard of proof, and penalties that while severe are restitutive and reversible if it can be shown the decision was incorrect.
To address the specific historical point. Beliefs in the existence of witchcraft are widespread historically. However they do not lead to widespread with hunts and panics (as opposed to one off cases) in societies that do not have a predominantly state based legal system with a distinct cjs. The great European witch hunt arose during the so-called 'judicial revolution' which saw a radical movement from customary community based law to royal law and from restitution to retribution. In that system, once the elite had come to believe that (a) witchcraft existed and was a serious threat and (b) that most witches were escaping punishment, the witch hunt was inevitable. The modern counterpart of this is such phenomena as the panic over supposed 'satanic child abuse' in the US and UK.