In a recent column, Barbara Kay extends the "broken window" theory of crime to a discussion of marriage. The concept, originally devised by social theorists James Q. Wilson and George Kelling -- and later popularized in Malcolm Gladwell's 2000 bestseller, The Tipping Point -- looks at the relationship between major crime and minor disorder. Breaking the window of a seemingly abandoned car turns it into a derelict, so that a vehicle no one touched for weeks is stripped clean within hours. "Gay marriage is that broken window," writes Ms. Kay. "Continuing vandalism will see marriage abolished altogether." Assuming that the...