Well, it certainly shouldn't discourage it, and if David Cameron thinks that's currently the case, then maybe he has a point. But I honestly don't think the tax system should encourage marriage either.
It's not that I don't believe that marriage provides the most stable environment for children to be brought up in. It quite clearly does. But is providing tax incentives to get married really likely to provide more stable, loving homes - or might it actually achieve just the opposite?
Okay, so I probably move in rather traditional social circles compared to some, but most people I know got married because they believed they had found their soulmate, not because they wanted to find a way of knocking £200 a year off the income tax bill.
If there really is anyone out there who got married for those sorts of reasons - and that I rather doubt - then they are probably three quarters of the way to the divorce court already.