The Post editorial board argues that “society will be better served by retaining the traditional, time-tested definition of marriage.” This same claim was used in service of anti-interracial marriage laws.

The 2013 politics here is kind of interesting. Same-sex marriage is an issue that City Council Speaker Christine Quinn -- who is openly gay -- has been advocating for years. Yesterday, she was in Albany as four lawmakers who previously opposed the bill announced their support for it.

The letter allows de Blasio to criticize the New York Post, which, in front of Democratic primary voters, is usually advantageous. It also gives de Blasio an opportunity to inject some of his own personal narrative -- his inter-racial marriage -- into a debate that is closely associated with Quinn.