BBC - Future - The best way to win an argument: 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.
So this is something worth bearing in mind next time you're trying to convince a friend that we should build more nuclear power stations, that the collapse of capitalism is inevitable, or that dinosaurs co-existed with humans 10,000 years ago. Just remember, however, there's a chance you might need to be able to explain precisely why you think you are correct. Otherwise you might end up being the one who changes their mind.