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It is a standard view among Moslem Philosophers SInce Avicenna that the propositions of empirical sciences are in
fact the conclusions of an imperceived syllogism. According to this view the validity of an inductive argument is based upon an implicit deduction which accompanies every inductive argument. The major premiss in the deduction is the conditional "if the sequence of events is a matter of chance it would not be possible for it to occur frequently". This conditional proposistion is often referred to as the "Rule of AI-Ettefaghi". However, the correctness of the rule has been called into question recently, notably by Shahid Sadr.
This paper is an attempt to trace the rule in the writings of Aristotle first, and then to compare the use it is being put into in his writings with those in the writings of Avicenna. It is shown here that when the rule is used in Shifa '5 Kitab al
Borhan it is used to justify our inductive generalizations (i.c, it is used to identify a cause that we know of its existence
already). This is a totally different application of the rule from what we find in Aristotle's Physics. It is also explained that in Kitab al- Borhan the rule is not used to make a necessary connection out of a contingent one, as it has been assumed nowadays erroneously. Also some difficulties with the critic's interpretation of the rule is being discussed.