When certain politicians say something is common sense, they mean that it makes sense to them, and should to you, without being examined or discussed. Which means they don't intend to show why it might make sense. So in calling something common sense, what that sort of politician means is that people who agree with that sort of politician's ideas will surely agree with this idea, and no further elaboration is required. Why go on and on? It's just common sense. Surely you agree with common sense, don't you? And it's just common sense not to let anyone sense that you don't agree with common sense.