Consequently, the countless traditions ascribed to al-Zuhrī and ʿUrwa (among others) by later sources most likely do not reflect actual transmissions so much as the reputation of these two scholars as the earliest and most important authorities on Muhammad and the rise of Islam. Traditions conveying what the community believed to be true about earliest Islam would have been attracted magnetically to their names by sheer virtue of their fame. One need not imagine some sort of conspiracy or even a willful falsification, as some have wrongly maintained, to explain such developments: members of the Islamic community would rather “naturally” have assumed that traditions about the Prophet held to be true must have originated with one of these two sagacious men. As Harris Birkeland comparably observes with regard to Ibn ʿAbbās, whose reputation as a great authority on tafsīr inspired later transmitters to attribute a “great ocean” of exegetical traditions to his authorship, “so it is even today, for instance in traditionalistic, rural communities in Norway. Every accepted religious opinion is attributed to Christ, Paul, or Luther.” He continues to note, perhaps even more tellingly, that “it would provoke great indignation if anybody should happen to express the opinion that Luther ever believed in pre-destination. Every believing peasant would deny that statement most decidedly.”33 Surely this is not the result of some widespread conspiracy to deceive. Accordingly, one would in fact expect to find that the chains of transmission in the sīra literature regularly ascribe much of their material to ʿUrwa and al-Zuhrī, and consistent attribution of traditions to these early authorities does not necessarily indicate the authenticity of these attributions. It is instead altogether likely that established patterns of authoritative transmission had become fixed according to traditional forms rather early on, and these patterns provided paradigms for the isnāds that were attached to later traditions. Insofar as the Islamic community believed such later traditions to be true, there was not so much a need to invent phony isnāds to justify their authenticity; rather, the “truth” of the traditions themselves would make their attribution to authoritative scholars such as ʿUrwa and al-Zuhrī mostly a foregone conclusion.34
In the face of such concerns, the methods of isnād criticism, especially as developed by Joseph Schacht, G. H. A. Juynboll, and, most recently, Harald Motzki, can often be somewhat helpful for assessing the probability of attributions to such early authorities. Through an extensive correlation of the different isnāds assigned to a particular tradition in later sources, one can occasionally identify a plausible date for the tradition, as well as the individual who was most likely responsible for initially placing it into circulation. The Islamic tradition itself of course has long-established methods of isnād criticism designed to assess the authenticity of the numerous ḥadīth ascribed to Muhammad, the vast majority of which have been regarded as spurious even in the Islamic faith. Yet modern scholarship on Islamic origins generally approaches these chains of transmitters with a great deal more skepticism than the Islamic tradition, and consequently it has developed its own methods for evaluating both the isnāds themselves and the various traditions, or matns, to which they are attached. There is certainly warrant for such suspicion, since forgery of ḥadīth and their isnāds was pandemic in early Islam: the ninth-century Islamic scholar of ḥadīth al-Bukhārī is said to have examined 600,000 traditions attributed to the Prophet by their isnāds, and of these he rejected over 593,000 as later forgeries.35 Matters are even worse in regard to the sīra traditions, which medieval Islamic scholars regarded as having even less historical reliability than the rest of the ḥadīth.36 With good cause, modern scholarship on Islamic origins has merely intensified the Islamic tradition’s own internal skepticism of prophetic traditions in its efforts to reconstruct the beginnings of Islam.
Ignác Goldziher and Schacht after him were among the first Western scholars to draw attention to the artificial and historically problematic nature of very many isnāds that the Islamic tradition viewed as credible, casting considerable doubt on the authenticity of the traditions that these isnāds claimed to validate.37 Schacht, however, developed a method of analysis that allowed for the extraction of historically valuable information from these partially fabricated lists of transmitters. This approach, generally known as common-source analysis, compares all the various isnāds assigned to a particular tradition in different sources in order to identify the earliest transmitter on whom all the highly varied chains of transmission converge, the so-called common link.38 As Schacht rather reasonably concludes, this figure is most likely the person who first placed a particular tradition into circulation, since numerous isnāds all unanimously identify him as a source. Otherwise, it is difficult to explain how these highly variegated chains of transmission could converge on this single individual as their earliest common source. The alternative, that somehow all of these different isnāds have by chance invented the same early transmitter, is comparatively unlikely. Thus some degree of confidence may be placed in identifying the common link with the earliest history of a particular tradition, although as will be seen in a moment, even this seemingly fail-safe method is not without significant problems and uncertainties.
An inherent skepticism pertains to the list of transmitters preceding the common link, however. By definition these figures do not vary in any (or almost any) of the isnāds transmitting a particular tradition, which could on the surface seem to speak for their authenticity. Nevertheless, there are considerable reasons for doubting the historical accuracy of these earliest transmitters, and it seems rather likely that these oldest links in these chains were invented early in the process of transmission in order to give these traditions sanction by linking them with Muhammad and other revered figures from the earliest history of Islam. Particularly important is Schacht’s famous observation that isnāds tend to grow backwards. Schacht has argued rather compellingly that the earliest links of many isnāds, particularly those identifying the Prophet, the Companions, and the Successors as sources, are in fact the most likely to be falsified. Moreover, he concludes that the closer the original source of the tradition is to the Prophet himself, the more likely that the isnād and the tradition itself are counterfeit and late, making traditions ascribed directly to Muhammad both the latest and most likely to be forged.39 Recent studies by several scholars who are otherwise sympathetic to Schacht’s methods have cast significant doubt on his second principle, and the notion that isnāds ascribed to earlier authorities are categorically more likely to be both recent and inauthentic has come into question.40 Yet while many of these studies have shown that such traditions are not necessarily more recent than others, they nonetheless generally confirm that their ascriptions to early authorities are overwhelmingly false, verifying the most important aspect of Schacht’s hypothesis. Suspicion of these earliest transmitters is further warranted by the fact that prior to the second Islamic century isnāds usually were not used in the transmission of early Islamic traditions, including the sīra traditions in particular.41 At this late stage, chains of transmission suddenly had to be constructed, as is evident in Ibn Isḥāq’s use of only a very basic and nascent form of isnāds.42 When there was uncertainty regarding a tradition’s origin, which surely was often the case after over a century of anonymous transmission, traditions were ascribed to great figures from the past, and from this chronological distance it seems rather likely that the nearer the isnād approaches to Muhammad, the less likely it is to reflect an actual pattern of historical transmission.
Despite the apparent promise of Schacht’s approach, however, significant unresolved issues remain concerning its reliability, and several recent studies have raised important concerns about the accuracy of common-link analysis for dating early Islamic traditions. The most dramatic challenge to the method has come from an article by Michael Cook, which demonstrates that in certain instances where one can actually test the reliability of common-link analysis through alternate means of dating, the method fails to date material accurately.43 Cook’s study examines several early Islamic eschatological traditions, all of whose dates can be determined from their content, using a rather standard method for dating apocalyptic material. These traditions all purport to predict the future, and up to a certain point they exhibit astonishing accuracy, which is undoubtedly due to the