Fair enough, but can I ask why? Eusebius and other early historians give the list from Peter to the 300s A.D., and from then on I'm pretty sure we have contemporary documentation in every century till the present.
Not quite. The list has been modified several times over the centuries and was certainly "backfilled" to Peter.
For example:
Corrections Made to Official List of Popes
Revelations of "Pontifical Yearbook 2001"
VATICAN CITY, JUNE 5, 2001 (Zenit.org).- New historical research has prompted almost 200 corrections to the existing biographies of the Popes, from St. Peter to John Paul II.
The discoveries are included in the opening pages of the new edition of the "Pontifical Yearbook 2001," the "who's who" of the Catholic Church published by the Vatican Press.
The 13 pages entailed are the most rigorous study to date on the history of the papacy, confirming the uninterrupted succession of the Bishops of Rome. Researchers, however, are uncertain of the exact dates of the first pontificates and, in one case, doubt the exact order. This is why the yearbook does not assign a succession number to each pontiff.
Including Karol Wojtyla, there have been 264 Popes, but 266 pontificates. Benedict IX reigned three times between 1032 and 1048. The first time, his pontificate was interrupted by the intrusion of Sylvester III. After he returned to Peter's Chair, Benedict IX resigned and was succeeded by Gregory VI. Then, following Clement II's death, Benedict IX returned to the papacy for the third time.
The yearbook has notable improvements, including a new graph that has done away with 500 pages. The new volume has 2,068 pages.
The most interesting corrections to papal history correspond to the chronology of the first two centuries. Exact dates of the pontificates are uncertain. A dozen Popes have been given two possible dates, in keeping with historical calculations.
The family name of one Pope has been corrected, and the listed birthplaces of nine Popes have changed.
Spain lost claim to a native-born Pontiff. St. Damasus (366-384), whose literary work is testified by the catacombs, and who was considered a native of the Iberian Peninsula, was, in fact, born in Rome.
The corrections result from the enormous work carried out by historian Giovanni Maria Vian, member of the Pontifical Committee of Historical Sciences, who was also a scientific adviser of the "Encyclopedia of Popes," published last year by Treccani, Italy's most prestigious literary publishers.
Vian explained the corrections to the Italian newspaper Avvenire. He said that in the second half of the 20th century, historical research has taken some important steps, "therefore, the chronology of the Popes of the first two centuries is more uncertain."
The most significant historical doubt affects Peter's second successor. After Linus, Cletus (80-92) or Clement could have been Pope, either between 68 and 76; or between 92 and 99. Therefore, one could have been Pope before the other.
Yet, "the new discoveries of those years reinforce the credibility of the succession of the Bishops of Rome," Vian concluded. The "Pontifical Yearbook 2001" may be purchased on Internet at http://www.ixtmedia.com.
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