Politics is about choices. We elect leaders to make choices about war and peace, taxation and public expenditure, environmental protection and economic development. But, while we want our leaders to make choices, we punish them for making choices we don’t like. Unsurprisingly, politicians respond with creative use of ambiguity, giving different messages to different audiences, and trying to appear decisive without offending anybody.

Nowhere is this more true than in relation to climate change. When he was a believer in a market-based climate policy, Malcolm Turnbull accused Tony Abbott of being a "weathervane" on the issue, "first publicly advocating the blocking of the [emissions trading scheme], the passing of the ETS, the amending of the ETS and, if the amendments were satisfactory, passing it, and now the blocking of it".