Why do Popes change their names on taking office?

Karol Wojtyla becoming Pope John Paul II didn’t surprise me, since he wanted to honor John Paul I, who in turn wanted to honor John XXIII and Paul VI. But what did surprise me is how rarely Popes have kept their own names. As far as I can tell, the last time that happened was when Marcello Cervini became Pope Marcellus II in 1555. According to this site (which also lists the birth names of popes and antipopes)

But they don’t say why the custom began. Anybody?

On a related note, why are there so few new papal names? There was John Paul I, but both John and Paul were used before. Before that, the last legitimate pope to be called by an original name was (as far as I can tell) Pope Lando, over a thousand years ago. That roughly corresponds to the time that name changes became common. Coincidence?

I think it’s the old tradition of taking a Saint’s name?

I can’t directly answer the question about why the tradition started but I’ve lived through enough papal ascendencies to know that the new pope’s new name is taken as an indicator of how he will conduct his ministry.

You mentioned John Paul I & II, and honoring predecessors. That would make sense of the lack of new papal names. If you name yourself Pope Pius the Next you’d be indicating you will emphasize policies that were important to Pope Pius the Previous. If, on the other hand, you called yourself Pope Unknown, or Pope Mystery, or Pope Never-Heard-Of-Him no information is given. The only good way, IMHO, of coming up with a new papal name is to name yourself after someone who is both well enough known to be recognized and sufficiently pope-like (without having been a pope, of course) to indicate your chosen course. Pope Pluto has a nice ring to it, but I don’t think it’s gonna happen.

While typing this I was wondering what would happen if U.S. Presidents had this tradition. I assume our current president would be called President Ronald III. Clinton would probably have picked John (Kennedy) II (or III or IV, as needed), although the Republicans would probably lobby for Warren II after the fact. Of course everyone would try to get back to George Washington but George III has some nasty historical connotations, so I don’t suppose that would happen. Just think what this would add to the campaign: “If I’m elected I pledge to call myself President Woodrow II. I also happen to have a draft of a memo from the other side indicating they are thinking of Millard III. Is that what you want for the next four years? Think of the children!”

Google is our friend, too, not just Snopes. It returned this fragment from a now-dead link:

The custom of changing names upon election, however, did not become common until the election of Pope Sergius IV (1009 1012), whose baptismal name was Peter. …

Other sources show Sergius’ original name as (versions vary) Pietro Boca di Porco, “Peter Pig’s Snout” - he may not have wanted to hand that name down to history.

Okay, wait a minute. Pope Lando? Was he succeeded by Pope Han?

Well, after Pope Lando gambled away the Vatican in a game of sabacc, it kind of soured the Church on the idea of popes with new names.

There is an ancient tradition in the Church that an adult being baptized into the Church would take a new name to show that s/he had put aside her/his old life and was taking on a new life as a Christian.

In the same way, people who join religious orders generally take a new name when they take their vows, Bill Jones becoming Brother Theophilus and Cynthi Smith become Sister Mary George, leaving behind the lives they had led under their birth names.

I would guess that the same impetus is behind the taking of a new name by the pope. In ascending to the papacy, he is putting behind his old life (theoretically with all the personal cares and political allegiances) to take on the role of leader of all people in the Church. His new name is symbolic of his new role.

I do not have a citation to prove that the actions of a new pope are for the same reasons as the others noted. It is, however, a reasonable supposition. (I am also fully aware that any number of popes have not separated themselves from the politics that got them the job. The symbolism remains whether or not a specific pope has the strength of character to abide by that expected separation.)

I do know that up until Vatican II, nuns were recquired to take a new name upon entering the convent.

Lando’s not a system, he’s a Pope.

Thanks to Elvis for finding what may be the key to the mystery: it probably isn’t coincidental that the first pope to take a new name was a man named Peter (Pietro).

Catholics have always looked upon St. Peter (Simon bar-Jonah, whom Jesus himself named Peter) as the first Pope, and he’s always held a unique, special place of honor and reverence. You’ll note that NO pope has ever adopted the name “Peter,” for that very reason. (For some reason, a superstitious legend has arisen that the world will come to an end if any future pope DOES take that name.)

It seems plausible that the first Peter elected to the papacy naturally decided it was best to call himself Sergius, to preserve the unique place of Simon Peter. (He probably didn’t know he was setting a precedent and starting a new tradition.)