One of the properties of independence friendly (IF) first-order logic as discussed, e.g., by \textit{J. Hintikka} in his ``The principles of mathematics revisited'' [Cambridge University Press, Cambridge (1996; Zbl 0869.03003)] is that ``it defines its own truth-predicate in certain models, like for instance, in the standard model \(N\) of PA'' (p. 40). This property is proved in section 2 of the paper. Being used for formulating descriptively complete nonlogical theories, IF logic enables us ``to use more deductive methods in logic'' by finding ``stronger and stronger axioms for some of our mathematical concepts'' (p.\ 43, paraphrasing Hintikka). The authors now show that the use of more deductive methods in the case where the underlying logic has the properties of IF logic leads to some undesirable consequences (p.\ 44). They give evidence for this evaluation by considering a proof system \(\vdash\) in IF languages for elementary arithmetic.