Our state doesn't exist to enforce morality: it is there to define a bottom line of acceptability. Often this is below accepted norms, although occasionally it far exceeds them. Formula One boss Max Mosley will discover soon whether British law will protect his privacy while he engages in acts that many would find immoral.
The Church of England itself has difficulty reconciling morality and law, causing the current row over homosexual bishops.
People aren't stupid. They hear politicians' words in the context of who is saying them and such messages will more often impact people's view of politicians than affect their behaviour.
Politicians know this, which is why David Cameron started his leadership attracting the middle ground with fluffy statements about hugging hoodies and is now reassuring his core vote by claiming that those who are poor or overweight have only themselves to blame.
Nothing Cameron says changes people's behaviour. It merely positions him as a product in his chosen market. Widespread speculation about his alleged dalliances with illegal substances in his youth undermines his bid for the moral high ground.
Governments should be careful when they legislate for morality. Anti-discrimination and environmental protection statutes are rare moral laws that were passed because standards of common behaviour were below what politicians deemed acceptable.
Mostly, people fail to live up to their own moral standards, so how can they aspire to be a politician in a world of black-and-white morality? This absolutism creates unreasonable expectations of politicians' behaviour.
It leads to a Parliament with too many barristers and too few bus drivers. So I'll vote for the politician who bids for the moral low ground.
Alex Hilton is a Labour parliamentary candidate and founder of political blogs Labourhome and Recess Monkey