You may be right, Will, but you may have misunderstood the question. Since JPI and JPII were also Johns, will they be counted as Johns in the numbering system? If so, that would make the next John the twenty-sixth pope - discounting antipopes - to reign under that name.
To make matters even more complicated, I believe there was an earlier antipope John whose number was NOT taken by the next legit pope John; as I recall, there was John XIX, and then an antipope John XX, and then the next pope John reigned as the XXI.
In cases where such ambiguity exists, does each new pope get to choose his number as well as his name?
John Paul I was the first by the name of John Paul, not the 24th by the name of John. A future Pope John would be the 24th of that name, just as a future Pope Paul would be the 7th of that name.
It makes sense that a Pope John who followed near in time to a false Pope by that name would take a different number, too, in order to avoid confusion. If enough time had elapsed and if the anti-Pope were insignificant enough to be forgotten, it would undoubtedly be a different matter.
Because there’s already an established custom of referring to the two John Pauls as I and II of a new name, the next John should be XXIV and the next Paul should be VII. Otherwise people will wonder where the “missing” ones went. Pity the poor Church historians and apologists of the future, who would have to try to explain that bit of strangeness in 100 or 1000 years…
If I’m remembering correctly, the new Pope doesn’t actually pick his “number,” just the name by which he will be known. He naturally receives the next “number” in line for that name. When Cardinal Ratzinger chose his papal name, did he just say “Benedictus,” or did he add the Latin for “the Sixteenth”? (Even if it was the latter, I expect a quiet correction would have been issued if he’d picked the “wrong” number.)
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