‘…Those in the second group did something subtly different. Rather that provide reasons, they were asked to explain how the policy they were advocating would work. They were asked to trace, step by step, from start to finish, the causal path from the policy to the effects it was supposed to have.
The results were clear. People who provided reasons remained as convinced of their positions as they had been before the experiment. Those who were asked to provide explanations softened their views, and reported a correspondingly larger drop in how they rated their understanding of the issues. People who had previously been strongly for or against carbon emissions trading, for example, tended to became more moderate – ranking themselves as less certain in their support or opposition to the policy….’
via BBC – Future – The best way to win an argument.