Idraj(Insertion) in the Hadith , Types, Causes and Consequences

Due to the vulnerable  nature of hadith, taking benefit of this precious treasure requires some  provisions. One of these provisions is noticing the defects of Hadith as  to enable the hadith researcher remove its undesirable consequences in the field of understanding Hadith.  One of the possible damages in the Hadith is "Idraj(insertion)  in the text of Hadith" i.e.  the hadith text being mixed  with the narrator's word. Since a very slight change in the Hadith sometimes prevents us from understanding the real meaning intended by the infallible Imams and will end with a different perception, considering the damage of "Idraj" is of great significance.
This paper with  descriptive- analytical method concludes that  if there is  knowledge to the damage of "Idrag",  the primitive apparent meaning of hadith cannot be accepted  and if there is doubt  about the occurrence of this damage, based on the rational  principle of non-existence of every uncertain phenomenon, every possibility contrary to the apparent meaning is negated.