Social democracy "works" until it fails! Weird definition of success! That's what the crisis in Europe shows. Social democracy works to save capitalism because that is its goal. It's not socialism, and never was. Capitalism is the rule of the tiny class of corporate owners. Socialism is the ownership and control of a countries productive assets by the people themselves (throught a number of mechanisms). Cuba is an example of socialism that, against enormous odds, is succeeding. But it could be much more successful -- and can't last forever -- unless some richer countries go in the same direction.