From 3 Commencement Speakers, a Familiar Script If you're delivering a commencement address, you must observe certain customs. No exceptions are allowed, not even for the biggest of shots, a reality reinforced in speeches made in the last few days by President Obama, Mayor Michael R. Bloomberg and the would-be president Mitt Romney. One of the first mandates for any graduation speaker is to give a shout-out to a newly liberated group that labored for years under a form of oppression. Those people are called parents. Mr. Bloomberg's two speeches over the weekend, at Franklin and Marshall College in Pennsylvania and at the University of North Carolina, were a good example. "They are sitting out there this morning, beaming proudly," he said, using identical language at both schools, "and not even thinking about what it cost to get to this day." Having sat out there myself, three times, I'm pretty sure that more than a few moms and pops were, in fact, reflecting deeply on their pocketbooks. "Or," the mayor continued, "what happens if you can't get a job and have to move back home." (Uh-oh, some parents no doubt thought. Did he have to remind us of that dread possibility?) Inevitably, the speeches by these men have been analyzed for political significance. Mr. Bloomberg went out of his way at liberal Chapel Hill, N.C., in a state whose voters last week approved a ban on same-sex marriage, to reaffirm his conviction that gay men and lesbians should have a right to wed. Mr. Romney said the opposite, insisting on Saturday at Liberty University, a Virginia school founded by the evangelical preacher Jerry Falwell, that "marriage is a relationship between one man and one woman." Monday, Mr. Obama journeyed to one of his old haunts, Morningside Heights in New York, to tell nearly 600 women graduating from Barnard College that they should "fight for a seat at the head of the table." All three men were preaching to the choir. Wouldn't things have been more interesting if Mr. Bloomberg or Mr. Obama had gone to Liberty to say his piece, and if Mr. Romney had expressed disapproval of same-sex marriage in a place like Chapel Hill or Barnard? But that would have required acts of daring that you will probably see the same day that restaurants in Saudi Arabia start serving beer and wine. Politics aside, these speeches have certain elements in common. Splashes of humor, preferably self-deprecating, are essential. Mr. Obama had that part down cold. Mr. Bloomberg held his own. Mr. Romney? Not so much, though he did try, as when he mentioned that not everyone at Liberty had graduated in four years, like the fellow who "said that he completed his degree in only two terms: Clinton's and Bush's." It is obligatory for the commencement speaker to throw in a few local references to give the appearance of being intimately familiar with the territory. Mr. Bloomberg was especially adept at that. At North Carolina, he alluded to several of the university's customs, and mentioned its Latin motto, Lux Libertas. Sounded like a reference to free soap. Turned out to mean Light and Liberty. Above all, a speaker must be ready to dispense all sorts of advice for the young people heading out into the world. Nothing beats telling them, in effect: You know, you could do a good deal worse than to be like me. Mr. Obama cited his own rocky early efforts as a community organizer in Chicago to illustrate the importance of perseverance. Mr. Romney presented himself and his father, George Romney, as models for the primacy of family. As for Mr. Bloomberg, he couldn't resist invoking one chapter of his life after another to tell the graduates that success can be theirs if only they seize it. To underline that point in his Chapel Hill talk, he offered the English version of another bit of (probably faux) Latin: Nil illegitimi carborundum. And what commencement would be complete without the main speaker's letting the graduates in on a little secret, namely that, as Mort Sahl used to say, the future lies ahead? On this score, too, the political men didn't disappoint. We'd like to think that the students had figured that one out on their own. But, hey, you never know.