Often, I see ahadith cited, especially from those major collections other than the sahihain, with their authenticity graded by al-Albani. From perusing his selected bibliography on Wikipedia, I can see that he has done a fair amount of writing in this regard, and is apparently considered a hadith scholar of some renown (and more than a little criticism).
Traditionally, ilm al-rijal is a major factor in determining whether any hadith is authentic; an otherwise flawless hadith could still be deemed da'if if anybody in the chain of narration is considered questionable. However, while the major collections were compiled at a time when many of the narrators were still alive (and thus able to be studied), or were personally known by people who were still alive (and thus able to be studied), al-Albani himself was born significantly later and would (presumably) only be able to rely on written accounts thereof by the scholars of that time.
Given that these contemporary scholars would've had access to much of the same information (although maybe not all at once), one would think there would have been significant research into how authentic any particular hadith was at the time (either by these scholars or in the generations following as the information disseminated among the Islamic world).
The fact that al-Albani's classification is specifically mentioned suggests to me that either:
- No major scholar considered authenticity of these hadith important enough to study for over a thousand years (highly unlikely)
- Most of the work of these earlier scholars was somehow lost to the ravages of time (possible, but still doesn't seem too likely)
- al-Albani's methodology and/or the information available to him was somehow different than that of earlier scholars.
In an attempt to understand the likelihood of the third position, my question lies thus: What was al-Albani's methodology for determining authenticity of a hadith? How, if at all, did it differ from the methodology used by the contemporary scholars?