The liberal mentality, encountering certainties that seem to place obstacles in the pursuit of desire, is irresistibly tempted to undermine them. If people are certain that marriage, for example, is a relation between man and woman, the liberal instinct is to see this as a constraint on homosexuals. The response is therefore to propose marriage between people of the same sex, which is offered as an entirely innocent reform, a mere expansion of our freedoms. If that attitude is pursued to its logical conclusion, then incestuous relations too could be dignified with the name of “marriage,” precisely because the name would have lost its dignity. If all social life is founded in human choice, and no institution derives its validity from any other source, then there are no certainties and no institutions that encapsulate sacred ties. Roger Scruton