ABSTRACT
As an example of the need for some humility, consider the pro-nuclear arguments put forward that the risk of expected fatalities (i.e. the fatalities in the mean or the first moment) attributable to nuclear power as compared to other choices indicates its relative safety and this should therefore determine the debate. (The argument is often not well advanced because of the presentation of numbers; as stated earlier the layman has experience of numbers between one and say one hundred but little experience of numbers like a million and even less of numbers like one in a million-let alone 10−6.) It seems to surprise the promoter of the argument that its merits are not overwhelming and that fears of low probability but large casualties should appear to exercise a powerful effect upon the public mind. Yet there is nothing sacred about first moments; it is perfectly reasonable for a community and its individuals to be concerned more with the lesser probability of a communal catastrophe than the greater probability of a few deaths. And, similarly, a society that accepts 3000 deaths per year on its roads (out of say one million deaths overall) but not the two hundred deaths of an Aberfan or similar community disaster is not behaving illogically in its instinctive weighting to higher moments.
