The Pseudo-Isidorian Decretals (or False Decretals) are a set of extensive, influential medieval forgeries written by a scholar (or group of scholars) known as Pseudo-Isidore. The forgers' main object was to emancipate bishops from the influence of archbishops, synods, and secular power by exalting papal supremacy.
The authors, using the pseudonym of Isidore Mercator, were probably a group of Frankish clerics writing in the second quarter of the 9th century. To defend the position of bishops against metropolitans and secular authorities, they created documents purportedly authored by early popes and council documents.
The Carolingian Empire in the second quarter of the 9th century set the stage for the forgers. Although Louis I the Pious was deposed by his sons in the early 830s, he soon regained the throne. Archbishops and bishops played important roles, imposing penance on Louis for his allegedly-sinful life and paving the way for his removal. When Louis regained the throne, some church dignitaries were stripped of their bishoprics and exiled.
The Pseudo-Isidorian Decretals and fictitious letters from Clement to Gregory the Great were incorporated in a 9th-century collection of canons purportedly by the pseudonymous Isidore Mercator. Collections of canons were commonly made by adding new matter to old; the forgers of the Pseudo-Isidore collection took as the basis of their work the Hispana Gallica Augustodunensis, interpolating their forgeries with the genuine material to provide credibility by association. The Liber Pontificalis was used as a historical guide, and furnished some subject matter. The Pseudo-Isidorian collection includes an earlier (non-Pseudo-Isidorian) forgery, the Donation of Constantine.
The principal texts are:
In addition to these four main pieces are other minor forgeries from the same workshop:
Much of the work is attributed to "Isidore Mercator", but this is almost certainly a pseudonym created by conflating the names of the respected ecclesiastical scholars Isidore of Seville and Marius Mercator. The work probably originated in the Kingdom of the Franks. The forgers' main object was to emancipate bishops from secular power and the influence of archbishops and synods, partially by exalting papal supremacy.
The author of one section identifies himself as Benedictus Levita ("Benedict the Levite" or "the Deacon"). His Capitularia Benedicti Levitae deal not with early church and papal letters as the others do, but with forged capitularies on religious and theological matters by Carolingian rulers (most notably Charlemagne) who provide the forger's alleged authority. It is still unknown if the differently-structured and -written Capitularia Benedicti Levitae slightly predated and inspired the authors of the false decretals or all were forged simultaneously.
The overall work was probably done by several authors under the editorial control of a learned man. Although certain identification of the compilers and forgers is probably impossible, Klaus Zechiel-Eckes has demonstrated that they used manuscripts from the monastic library at Corbie. Zechiel-Eckes has compiled evidence that an abbot at Corbie, Paschasius Radbertus (abbot 842-847) might have been one of those responsible for the forgeries. The forgers probably worked in the ecclesiastical province of Reims, and the complex was mostly complete by 847-852; the earliest known reference to the text was in 852. Its chief composer may have been ordained illegally by Ebbo, archbishop of Reims, during his brief and unlawful reinstatement (840-41). Whereas Zechiel-Eckes has argued for a date of composition in the 830's or early 840's based on evidence centring on the Council of Thionville, Eric Knibbs has recently argued for a later composition date in the 840's or early 850's, on the basis of language in the decretals which appear targeted to support Ebbo after his translation to the bishopric at Hildesheim in 845.
Seventy-five manuscripts of Pseudo-Isidorian material, differing widely from each other, have survived. The manuscripts have been traditionally divided into six or seven groups. Most comprehensive is the manuscript known as A1 by Hinschius, with the mid-ninth-century Vaticanus latinus Ottobonianus 93 its best representative. Equally important is class A/B The original manuscript of this class (ms. 442, written after 858) was preserved in the Beinecke Rare Book & Manuscript Library of the Yale University Library. A/B is best represented by Vaticanus latinus 630 (last quarter of the ninth century, from the Corbie scriptorium, and the Cluny version also dates to the mid-ninth century.
Class A2 dates to the ninth century as well. Outstanding examples of this class include the Ivrea Biblioteca Capitolare 83 from northern Italy and the Biblioteca Vallicelliana D.38 in Rome, from the ecclesiastical province of Reims.
Three more versions date from the 11th or 12th century:
Which manuscript class is the genuine forgery is difficult to determine. The ninth-century composition of A1, A/B, the Cluny version and A2 may indicate that the forgers originally circulated their work in several different versions to evade detection.
Efforts to publish the forgeries have been unsuccessful, with the Hispana Gallica Augustodunensis never published. Although several editions of the Capitularia Benedicti Levitae exist, the most recent (Monumenta Germaniae Historica, Leges, folio II, 2, 1831) is scholastically inferior to the 1677 Étienne Baluze edition. The False Decretals and the Capitula Angilramni have been published twice, with the 1863 edition by Paul Hinschius criticized for his choice of manuscripts. Hinschius also printed the genuine and interpolated parts of the collection by reprinting older versions of Pseudo-Isidore's genuine sources, making that portion of his edition critically unusable. Historians must return to J. Merlin's 1525 edition, based on a single 13th-century manuscript and reprinted in volume 130 of Jacques Paul Migne's Patrologia Latina.
For 150 to 200 years, the forgeries were only moderately successful. Although a relatively-large number of ninth- or tenth-century manuscripts is known (about 100 more-or-less complete manuscripts of the False Decretals, dating from the ninth to the 16th century, have been preserved), the canonical collections took little notice of the False Decretals until the early 11th century.
During that century, the situation changed rapidly under the impetus of the Gregorian reforms and the Investiture Controversy. Spurred by monastic reform movements and the efforts of some Holy Roman Emperors, a group of cardinals and a series of popes strove to cleanse the church of abuses and free the papacy from its imperial patronage (which had recently freed it from the influence of Roman nobles). The reformers' efforts soon conflicted with temporal power; the bishops of the Holy Roman Empire were crucial to the emperors' power, forming the backbone of their administrative structure. This mingling of spiritual and temporal power was wrong, according to the reformers; Saint Peter had condemned Simon Magus (the "Simon" of simony), who tried to buy spiritual power.
The alleged letters, allegedly from some of the most venerable Roman bishops, demonstrated that the emperors' practice contradicted the oldest traditions of the church. Collections of canon law rediscovered the False Decretals, since some were largely extracts of the forgeries. The texts were now used to increase scrutiny of the bishops, making them dependent on the pope.
This situation prevailed until around 1140, when the jurist Gratian published his Concordia discordantium canonum (increasingly replacing the older collections and soon regarded as authoritative). Although Gratian also indirectly used forged texts, his work ended the immediate influence of the False Decretals. The texts had become a basis for procedural law, but the bishops' independence was increasingly restricted by the Church of Rome.
During the Middle Ages, few doubted the authenticity of the alleged papal letters. This changed during the fifteenth century, when humanist Latin scholars such as Cardinal Nicholas of Cusa noticed bizarre anachronisms (such as the claim that Clement I had based the preeminence of local churches on the presence of pagan high priests). During the sixteenth century, Protestant ecclesiastical historians such as the Centuriators of Magdeburg (the authors of the Magdeburg Centuries) systematically criticized the forgeries without yet recognizing them as an interconnected complex.
The final proof was provided by Calvinist preacher David Blondel, who discovered that the popes from the early centuries quoted extensively from much-later authors and published his findings (Pseudoisidorus et Turrianus vapulantes) in 1628. Although Catholic theologians originally tried to defend the authenticity of at least some of the material, since the nineteenth century no serious theologian (or historian) has denied them as forgeries.