Earlier I was discussing a curious passage in Matthew 18:15-16:

Now if your brother sins, go and show him his fault in private; if he listens to you, you have gained your brother. But if he does not listen to you, take one or two more with you, so that on the testimony of two or three witnesses every matter may be confirmed.

The question I raised was, what are the additional witnesses testifying to? That they witnessed the brother doing the deed? Or are they testifying to the wrongness of the deed which they may or may not have seen their brother commit? It seems odd to get additional witnesses to testify to having seen the brother do the deed.

Upon further discussion I realise that I am projecting a modern distinction back into the biblical text. There is an interesting medieval method of proof or legal “evidence”, which survived in English law all the way to the 17th century, known as “compurgation” or “wager of law”. Basically, an accused could get several neighbours, normally a dozen, to take an oath that he is innocent and this was considered a valid defence. However at that stage of the law of evidence this was not a “scientific” procedure, it was not analysed through the lens of trying to ascertain the facts, they did not analyse the reliability of the witnesses, the likelihood that the oath was true, etc. It was, to put it bluntly, a matter of who was willing to put skin in the game to declare a person innocent (as obviously perjury was a crime).

They could analyse whether the witnesses were credible rather than reliable, i.e. that is, their moral quality and reputation for honesty and truth-telling, rather than whether they were in some physical position to have seen the deed, they did not scientifically analyse the eyesight of the witnesses or the lighting, etc.

From this position we can analyse the biblical law here as an inverse form of compurgation, where instead of taking an oath to declare the innocence of an accused, witnesses can take an oath to condemn someone guilty of a deed. The focus is not so much on whether the person was in a physical position to have seen the accused do the deed, the focus was on the willingness of the witness to put “skin in the game”, to swear an oath before God, to have a person condemned.

If the concern is that this may enable people to just get rid of their enemies by falsely accusing them, this has already been anticipated by Deuteronomy 19:16-20:

If a malicious witness rises up against a person to testify against him of wrongdoing, then both people who have the dispute shall stand before the Lord, before the priests and the judges who will be in office in those days. And the judges shall investigate thoroughly, and if the witness is a false witness and he has testified against his brother falsely, then you shall do to him just as he had planned to do to his brother. So you shall eliminate the evil from among you. And the rest of the people will hear and be afraid, and will never again do such an evil thing among you.

Thus, one accuses one’s enemies falsely to their own peril as the judges and priests can still investigate in the usual fact discovering way to determine the facts of the case, and if the testimony is found to be untrue, the false witness shall be punished with the same punishment.

In a way, oaths were not primarily “evidence” of a deed as we understand the term today in the epistemic context. Oaths were “democratic” means for meting out justice, where ordinary people can judge and condemn another by taking a binding oath to God, and in most cases ordinary citizens were competent enough to pass judgement on their fellow citizens, who would then be condemned by an oath, or as the biblical law requires, by an oath of two or three witnesses at the very least. Of course if they abused this power, then they would be subject to scrutiny by higher judges and priests who would employ scientific methods for discovering the facts and determine if the oath is true.

Despite the “moral” dimension whereby we analyse this sort of oath, it also makes epistemic sense. There is a “law and economics” logic to trusting in oaths which involves such “skin in the game”, especially when perjury was not merely jail but to be inflicted with the very same punishment. In that sense, such oaths, since it takes upon themselves the risk of such punishment, was all the more reliable and could be trusted.

I guess in this sense, “wager of law” is a pretty apt phrase to discuss this method of “proof”.