Rav Chiya bar Yosef uses the concept of "eiruv parshiyos" to explain why the phrase "ki hu zeh" in Shemos 22:8 really doesn't belong there but belongs (either solely or also) to the topic of loans in "im kesef talveh." There is a reference to a sugya in Sanhedrin; it cites the same phrase in the same pasuk. A sugya in the Yerushalmi in Shevuos also uses the same phrase. Some Mefrarshim state that the concept means that all the laws of "V'eileh Mishpatim" are mixed up. The only other reference found using a computer search was to a Tosafos in Nedarim 67b where it is used in a discussion of haforas nedarim for a Naarah Hamorasah from Sefer Bamidbar.

The Yosef Daas cites Rav Dessler's use in Michtav Me'eliyahu of "eiruv parshiyos". He includes it along with "ein mukdam umeuchar batorah" and with "kri uksiv" as examples of constructs that are unique to learning the Torah and not systematic, logical principles. But he also cites only the case of "ki hu zeh" and of course there are dozens and more cases of the other two constructs.

Are there other cases of "eiruv parshiyos" that are implicit? Am I making too much of the phrasing? The basic question is what is the significance of (and why create) a concept if it's only used in one (or possibly two) instances?

Thank you.

Alan Schoffman, Teaneck, New Jersey