In his 1950 book The Origins of Muhammadan Jurisprudence, Schact introduced the concept of the "Common Link" (CL) to refer to the earliest point at which multiple chains of transmission (isnads) intersect.
In reality, several isnads may have been fabricated and, in this case, a particular transmitter only turns up as a common link because several later figures falsely attributed the same tradition back to them.
It is up to the investigator to determine if a CL or PCL is authentic, and Juynboll argued that the historical plausibility of a common-link is raised the more PCLs converge on it.
Another term Juynboll introduced into common-link theory was a "spider"; this refers to single strands of transmission that completely bypass the CL of many other versions of a report in finding their way to the original figure believed to have conveyed the tradition.
[11] Direct forerunners to the ICMA approach, involving the combined study of the isnad and matn, included Jan Kramers' 1953 article "Une tradition à tendance manichéenne"[12] and Josef van Ess in his 1975 volume Zwischen Ḥadīṯ und Theologie.
[17] The primary advocate of ICMA in the initial stages of the development and application of the method was Motkzi; Motzki believed that the oral transmission of hadith would result in a progressive divergence of multiple versions of the same original report along different lines of transmitters.
By comparing them to pinpoint shared wording, motifs and plots, the original version of a hadith that existed prior to the accrual of variants among different transmitters may be reconstructed.
In addition, Motzki believed that a comparative study of the differences between reports could enable the identification of particular manipulations and other alterations.
[23] Third, hadith subject to ICMA analysis are still dated no earlier than sixty (or more[24]) years after the events that they describe, usually from the Marwanid period onwards.