In any debate there are particular key arguments that are used to undermine the opponent. A debate as heated as that over the importance, or not, of population growth is sure to feature these. It should be clear to readers of my essay published last week that I regard population growth as the core issue in any discussion on sustainability. Many of the arguments used by those who wish to dismiss or lessen the importance of population growth are false, misleading or simply mental tricks allowing their advocates the comfort of self-deception.