In his Masari’ al-musari’ (Qum: 1984, ed. H. al-Mu’izzi), a work devoted in part to a refutation of Ismaili theology as represented by Abd al-Karim Shahrastani, the Avicennian philosopher Nasir al-Din Tusi sums up in my view the best way to deal with their characteristic brand of tanzih. In criticizing Shahrastani’s account, Tusi writes (pp. 87-8, tr. Mayer, modified):
What [Shahrastani] describes is the teaching of the ta’limiyyun. For they say: ‘He, ,the exalted, is neither existent nor non-existent; instead, He is the origin of existence and non-existence, and likewise in the case of any two opposed things or two things hierarchically ranked, for He is exalted above either. Rather, He is their judge and their bestower, His most proper attribute being generosity’.
The response to them is: ‘bestower’ and ‘bestowed on’ are two things ranked hierarchically, and the judge between two opponents and the non-judge between them are two opposed things. In sum, this is like the talk of preachers and poets, and ill befits [an intellectual] wrestling match and debate.
Ismaili tanzih errs on the side of excess (just as, say, a hashawi, in his view of the nature of God, errs on the side of deficiency). Such positions are either so much rhetorical posturing or are just down right incoherent. The middle course, as in so many other areas, is the Avicennian view.