There has never been a Pope John XX, because the 20th pope of this name, formerly Petrus Hispanus, decided to skip the number XX and to be counted as John XXI instead. He wanted to correct what in his time was believed to be an error in the counting of his predecessors John XV to XIX.
Confusion in numbering Popes John results from an error in the textual transmission of the entry on John XIV (983/984) in the Liber Pontificalis. This entry originally specified not only the duration of his pontificate ("VIII mens." = eight months), but also the duration of his ensuing imprisonment by Antipope Boniface VII, "per IV menses" ("for four months"). In the 11th century, some time after the pontificate of John XIX, this entry on John XIV was misread to be referring to two different popes John, the first reigning for eight months and directly succeeded by another John reigning for four months:
- Iohannes m. VIII ("John, eight months")
- Iohannes m. IV ("John, four months")
In distinguishing these two Johns, the second one came to be numbered as "Iohannes XIV. bis" ("John XIV the second") and it was confused with a historic character, the cardinal deacon John son of Robert, who opposed Boniface VII after John XIV's death. Given the fact that the following Popes John, from John XV (985–996) until John XIX (1024–1034), seemed to have neglected the existence of John XIV "bis", Petrus Hispanus meant to correct this error by electing for himself the name John XXI.
Afterlife of Pope John XX
In modern times, some have used this discontinuity in numbering for arguing that the Church created this confusion by trying to suppress the existence of a very special Pope John, that is, of Pope Joan (see myths and legends surrounding the Papacy). However, this argument is in conflict with the chronology, given that the legend of Pope Joan, not attested before the 13th century, used to present her as a direct successor of Leo IV († 855), whereas John XIV "bis" as successor of John XIV would have to be a pope of the 10th century, and John XX, if suppressed by the Church, would even have to be a pope of the time between 1034 (death of John XIX) and 1276 (election of John XXI).
In the humorous fantasy novel Jurgen, A Comedy of Justice, by James Branch Cabell, the protagonist learns of this omission. He gains admission to Heaven by pretending to be Pope John XX, there being no one to contradict him by claiming the title.
- Reginald L. Poole: "The Names and Numbers of Medieval Popes," in: The English Historical Review, Vol. 32, No. 128 (1917), pp. 465-478, see especially pp. 474-475af:Pous Johannes XXko:교황 요한 20세ja:ヨハネス20世 (ローマ教皇)