When mathematicians say "handwaving" [and the idea that speed limits help reduce traffic victims is certainly handwaving] disparagingly, about someone's work, it means that the person has a) insight, b) realism, c) something to say , and it means d) he is right, because that's what critics say wehen they can't find anything more negative.

Der Amerikaner ist die Orchidee unter den Menschen
Volker Pispers