The ban would be irrational because there is no reason to think that batteries will suddenly start causing unacceptable rates of plane failure in the near futur

The ban would be irrational because there is no reason to think that batteries will suddenly start causing unacceptable rates of plane failure in the near future. Presumably such a blanket ban would come in the wake of a single high profile incident, so in fact I am saying quite the opposite of "we should only take precautions against things that have already caused problems." Taking precautions against things that happened, instead of things which are likely to happen in the future is irrational. Box cutters took down a few planes, so we banned them. This is an irrational ban, because box cutters now have an infinitesimally small chance of taking down planes. Whether box-cutters took down 4 planes or 100 planes in the past really doesn't matter since it does not indicate future performance.