Up until Tony Abbott became the leader of the Liberal Party, there was general agreement amongst Aussie political parties that an emmissions trading scheme would be desirable due to the scientific evidence of global warming.
flyingfox, this is not a criticism of you personally, rather a textbook case of
Hegelian dialectic (Thesis, anti-thesis ---> synthesis). Frame two extremes of the argument to mark the boundaries knowing full well most people will come to a conclusion somewhere in the middle (synthesis).
But the issue is the setting of the boundaries to "constrain" the debate within the broad structure that "the science is a given", rather than testing the science itself.