Keep in mind that even in the 15th century, scholars like Aeneas Silvius (Epistles) and Platina (Vitae Pontificum), using historical-critical methods, discredited the story. In the 16th century, scholars like Onofrio Panvinio (Vitae Pontificum), Aventinus (Annales Boiorum), Baronius (Annales) and others corroborated these findings. Even Protestant scholars found the fable untenable: Blondel (Joanna papissa) and Leibniz (Flores sparsae in tumulum Papissae). However, some Protestants, especially in America, have continued to use the fable to discredit the papacy, even though the fable is truly a fable. (The Fable of Pope Joan, Fr. William Saunders)
"John Anglicus, born at Mainz, was pope for two years, seven months and four days, and died in Rome, after which there was a vacancy in the papacy of one month. It is claimed that this John was a woman, who as a girl had been led to Athens dressed in the clothes of a man by a certain lover of hers. There she became proficient in a diversity of branches of knowledge, until she had no equal, and afterwards in Rome, she taught the liberal arts and had great masters among her students and audience. A high opinion of her life and learning arose in the city, and she was chosen for pope. While pope, however, she became pregnant by her companion. Through ignorance of the exact time when the birth was expected, she was delivered of a child while in procession from St Peter's to the Lateran, in a lane once named Via Sacra (the sacred way) but now known as the "shunned street" between the Colisseum and St Clement's church. After her death, it is said she was buried in that same place. The Lord Pope always turns aside from the street and it is believed by many that this is done because of abhorrence of the event. Nor is she placed on the list of the holy pontiffs, both because of her female sex and on account of the foulness of the matter." (Martin of Opava, Chronicon Pontificum et Imperatum)
This event is said to have taken place between the reigns of Benedict III and Nicholas I in the 850s. Versions of the story appear in sources earlier than Martin; the one most commonly cited is Anastasius Bibliothecarius (d. 886) a compiler of Liber Pontificalis, who would have been a contemporary of the female Pope. However, the story is not found in reliable manuscripts of Anastasius. In fact, only one manuscript of Anastasius' Liber Pontificalis contains a reference to the female Pope. This manuscript, in the Vatican Library, bears the relevant passage inserted as a footnote at the bottom of a page, out of sequence, and in a different hand, one that certainly dates from after the time of Martin von Troppau. In other words, this "witness" to the female Pope is likely to be based upon Martin's account, and certainly not a possible source for it. The same is true of Marianus Scotus's Chronicle of the Popes, a text written in the 11th century. Some manuscripts of it contain a brief mention of a female Pope named Joanna (the earliest source to identify her with a specific name), but all these manuscripts are, again, later than Martin's work. Earlier manuscripts do not contain the legend.
There is only one source for a female Pope which certainly antedates Martinus, and this is Jean de Mailly, who wrote slightly earlier in the 13th century. In his chronicle of Metz, Chronica Universalis Mettensis, he dates the scandal not to the 850s but to 1099, and writes:
From the mid-13th century onwards, then, the legend was widely disseminated and believed. Joan was used as an exemplum in Dominican preaching. Bartolomeo Platina, the scholar who was prefect of the Vatican Library, wrote his Vitæ Pontificum Platinæ historici liber de vita Christi ac omnium pontificum qui hactenus ducenti fuere et XX in 1479 at the behest of his patron, Pope Sixtus IV. The book contains the following account of the female Pope:
References to the female pope abound in the later Middle Ages and Renaissance. Giovanni Boccaccio wrote about her in De mulieribus claris (1353). The Chronicon of Adam of Usk (1404) gives her a name, Agnes, and furthermore mentions a statue in Rome which is said to be of her. This statue had never been mentioned by any earlier writer anywhere; presumably it was an actual statue that came to be taken to be of the female Pope. A late 14th century edition of the Mirabilia Urbis Romae, a guidebook for pilgrims to Rome, tells readers that the female Pope's remains are buried at St. Peter's. It was around this time when a long series of busts of past Popes was made for the Duomo of Siena, which included one of the female Pope, named as "Johannes VIII, Foemina de Anglia" and included between Leo IV and Benedict III. At his trial in 1415, Jan Hus argued that the Church does not necessarily need a Pope, because during the pontificate of "Pope Agnes" (as he also called her), it got on quite well. Hus's opponents at this trial insisted that his argument proved no such thing about the independence of the Church, but they did not dispute that there had been a female Pope at all.
The Tarot, which surfaced in the mid-15th century, includes a Papesse with its Pape (since the late 19th century called The High Priestess and the Hierophant in English). It is often suggested, with some plausibility although no real proof, that this image was inspired by the legend of the female Pope.
There were associated legends as well. In the 1290s the Dominican Robert of Uzès recounted a vision in which he saw the seat "where, it is said, the Pope is proved to be a man". By the 14th century, it was believed that two ancient marble seats, called the sedia stercoraria, which were used for enthroning new Popes in the Basilica of St. John Lateran, had holes in the seats that were used for determining the gender of the new Pope. It was said that the Pope would have to sit on one of the seats naked, while a committee of cardinals peered through the hole from beneath. Not until the late 15th century, however, was it said that this peculiar practice was instituted in response to the scandal of the 9th century female Pope.
In 1601, Pope Clement VIII declared the legend of the female Pope to be untrue. The famous bust of her, inscribed Johannes VIII, femina ex Anglia, which had been carved for the series of papal figures in the Duomo of Siena about 1400 and was noted by travelers, was either destroyed or recarved and relabeled, replaced by a male figure, of Pope Zachary (Stanford 1999; J.N.D. Kelly, Oxford Dictionary of Popes).
One legend says that Joan was the illegitimate daughter of a former Pope and had a vision from God that she should succeed her father and become Pope. Another legend says that a street in Italy is named after her and her body is buried beneath it. In some legends, Pope Joan is not murdered after being revealed as a woman. Instead she is deposed, lives the rest of her life in a convent and her son is made Bishop of Hostia. Here is a passage from a Berlin manuscript:
“She was deposed for her incontinence, and taking up the religious habit, lived in penitence for such a long time that she saw her son made Bishop of Hostia [Ostia, near Rome]. When, in her final days, she perceived her death approaching, she instructed that her burial should be in that place where she had given birth, which nevertheless her son would not permit. Having removed her body to Hostia, he buried her with honour in the Cathedral. On account of which, God has worked many miracles right up to the present day.” (Berlin Manuscript)
Since the 14th century, the figure of Pope Joan has taken on a somewhat saintly figure. There are stories of her figure appearing and performing miracles. Francesco Petrarch (1304-74) wrote in his Chronica de le Vite de Pontefici et Imperadori Romani that after Pope Joan had been revealed as a woman:
In 1675 a book appeared in English entitled A Present for a Papist: or the Life and Death of Pope Joan, Plainly Proving Out of the Printed Copies, and Manscriptes of Popish Writers and Others, that a Woman called JOAN, was really POPE of ROME, and was there Deliver'd of a Bastard Son in the open Street as She went in Solemn Procession. The book describes among other stories, an account of the purported Pope Joan giving birth to a son in plain view of all those around, accompanied by a detailed engraving showing a rather surprised looking baby peeking out from under the pope's robes. The book was penned "By a LOVER of TRUTH, Denying Human Infallibility." According to the preface the author had been "many years since deceased" and was "highly preferred in the Church of Rome." Furthermore, the preface indicates that the book was first printed in 1602.
Most scholars dismiss Pope Joan as a medieval legend. The Oxford Dictionary of Popes acknowledges that this legend was widely believed for centuries, even among Catholic circles, but declares that there is "no contemporary evidence for a female pope at any of the dates suggested for her reign," and goes on to say that "the known facts of the respective periods make it impossible to fit [a female pope] in" although this is disputed due to the Liber pontificalis, the only continuous record of ninth century Popes, not being considered entirely accurate with regard to dates of succession and deaths with many of these dates known to be wholly invented.
The legend of Pope Joan was initially discredited by David Blondel, a mid-17th century Protestant historian, who suggested that Pope Joan's tale may have originated in a satire against Pope John XI, who died in his early 20s. Blondel, through detailed analysis of the claims and suggested timings, argued that no such events could have happened.
The Catholic Encyclopedia elaborates on the historical timeline problem:
It is also notable that enemies of the Papacy in the ninth century make no mention of a female Pope. For example, Photius I of Constantinople, who became patriarch in 858 and was deposed by Pope Nicholas I in 863, was understandably an enemy of the Pope. He vehemently asserted his own authority as patriarch over that of the Pope in Rome, and would certainly have made the most of any scandal of that time regarding the Papacy. But he never mentions the story once in any of his voluminous writings. Indeed, at one point he mentions "Leo and Benedict, successively great priests of the Roman Church".
No source describing a female pope exists from earlier than the mid-12th century, almost exactly four hundred years after the time when Pope Joan allegedly existed. It is hard to believe that an event like a Pope unexpectedly giving birth in public and being stoned to death would not be mentioned by any writers or historians at the time. The recent historian of the legend, Alain Boureau (Boureau 1988), finds that the origins of the story are to be found in the carnival and parody traditions of the twelfth century.
Rosemary and Darrell Pardoe, authors of The Female Pope: The Mystery of Pope Joan. The First Complete Documentation of the Facts behind the Legend, are theorizing that a more plausible timeframe would be 1086-1108, when there were several antipopes, and the reign of the legitimate popes Victor III, Urban II and Paschal II was not always established in Rome, since this city was occupied by Emperor Henry IV, and later sacked by the Normans.
This is all in agreement with the earliest known version of the legend, by Jean de Mailly, as he places the story in the year 1099. De Mailly's story was also acknowledged by his companion Stephen of Bourbon.
It has been argued that manuscripts and historical records were tampered with in the seventeenth century, when Pope Clement VIII decreed that there had never been a Pope Joan. But this claim is highly unlikely: either passages would have to be physically erased from manuscripts - something that obviously leaves marks - or the manuscripts would have to be completely destroyed and replaced with forgeries. Modern scholars can date manuscripts quite accurately on the basis of the materials used, handwriting styles, and so on; any such tampering or replacement would be easily detectable. What is more, it would have required an immense conspiratorial effort to remove Joan's name from all documents in every library and monastery across Europe, a task almost impossible to carry out. Protestants of the time would have assuredly protected evidence in their possession that disparaged the papacy, further increasing the obstacles to the successful completion of any such plot.
Against the weight of historical evidence to the contrary the question remains as to why the Pope Joan story has been so often believed and revisited. Some, such as writer Philip Jenkins, author of The New Anti-Catholicism, have suggested that the periodic revival of what Jenkins calls this "anti-papal legend" has more to do with feminist and anti-Catholic wishful thinking than historical accuracy.
Alain Boureau (Boureau 1988:23) quotes the humanist Jacopo d'Angelo de Scarparia who visited Rome in 1406 for the enthronement of Gregory XII in which the pope sat briefly on two "pierced chairs" at the Lateran: "the vulgar tell the insane fable that he is touched to verify that he is indeed a man" a sign that this corollary of the Pope Joan legend was still current in the Roman street.
Medieval Popes, from the thirteenth century onwards, did indeed avoid the direct route between the Lateran and St Peter's, as Martin of Opava claimed. However, there is no evidence that this practice dated back any earlier, let alone that it originated in the ninth century as a deliberate rebuff to the memory of the female Pope. The origin of the practice is uncertain, but it is quite likely that it was maintained because of widespread belief in the Joan legend and that it was thought genuinely to date back to that period.
Although some medieval writers referred to the female Pope as "John VIII", the real Pope John VIII reigned between 872 and 882, and his life does not resemble that of the fictional female Pope in any way.
A problem sometimes connected to the Pope Joan legend is the fact that there is no Pope John XX in any official list. It is sometimes said that this reflects a renumbering of the Popes to exclude the woman from history. Yet as historians have known since Louis Duchesne's critical edition of the Liber Pontificalis, this renumbering was actually due to a misunderstanding in the textual transmission of the official papal lists, where in the course of the 11th century, in the time after John XIX, the entry on John XIV had been misread as being referring to two different popes of this name, who then came to be distinguished as Iohannes XIV. and Iohannes XIV. bis ("John XIV the second"). The existence of a "second" pope John XIV was widely accepted in the 13th century, and by consequence the numbering of popes John XV through XIX was regarded as being erroneous. When Petrus Hispanus was elected pope in 1276 and decided for the papal name John, he meant to correct this error in enumeration by skipping the number XX and having himself counted as John XXI, thus acknowledging the presumed existence of John XIV "bis" in the 10th century who had nothing to do with the alleged existence of a pope John (Joan) VIII in the 9th century.