General Election 2010

Sure, but it's not a bad message. stable families promote social cohesion, and statistically are more likely to raise better behaved happier children who do better in life. You can see why they'd use the tax system to promote it, as it should result in lower social costs and a net saving.

They are not using it to promote "stable families" they are using it to promote marriage (with the civil-partnerships thing being nothing more than a typical Cameron "look we have changed" gesture). It is grossly unfair, not to say outdated, patronising and without any evidence at all that it will have the desired effect. I think the tax break is going to be about £150 a year; worth getting married for? Or staying married for? It is pure idealogy.
A husband, let's say, er, Boris Johnson, cheats on his wife. They get divorced. He remarries, she does not but she chooses to live with her new partner in a happy and stable relationship. He gets the tax break, she does not. How exactly does this promote social cohesion?