| The ultimate usefulness of swearing before a God (if you believe in one) isn't that relevant. The psychological reason we tend to request it is because of something far simpler: it reminds us of our convictions. There was a study about a decade ago about this by some social scientists. They made 10 people swear on the ten commandments before making a test intended to check for their honesty, they made another group of people take the same test while taking an oath on a general document stating they'd be truthful, and finally they did the same test with a control group who wasn't asked to swear on anything. All participants were checked to be atheists (so not caring much for the words of any God) beforehand as well. The outcome was that generally speaking, just being asked to swear on something tended to remind people of their own convictions, which in turn tended to result in them answering the subsequent test questions more honestly. That's all swearing over a document really does - it reminds someone of their morals (usually with the intent of guilt tripping them into not lying afterwards). I don't know about any other social reasons why we do it, but that's the psychological effect it has. (This is presumably why you can do it on any document that you have a sufficient conviction of being important to you as well.) |