Doubled Over

Rebbe Meyer in the Mishna in Kiddushin (62a) derives from the תנאי בני גד ובני ראובן the need for תנאי כפול, we don’t assume מכלל לאו אתה שומע הן.  The simple understanding of this din would be that Rebbe Meyer also agrees that one can figure out the other side of the תנאי by one’s self but it’s a גזירת הכתוב that תנאי requires תנאי כפול.  However, the Gemorah in Nedarin 11 assumes the din of Rebbe Meyer applies to a neder as well.  There is on תנאי there, so why would Rebbe Meye require תנאי כפול?  The Achronim prove from here that it’s not just a din in תנאי, it’s a din in speech; when one’s dibbur is affecting a din, it must be clear from both sides.

However, the Gemorah in Shevous (36b) proves from the issur of a kohan that drank wine serving in the mikdash, which is expressed in the Torah as if they don’t drink, they won’t die, that we say מכלל הן אתה שומע לאו even according to Rebbe Meyer regarding issurim.  That is a proof from the lashan haTorah, it has nothing to do with dibbur, yet the Gemorah still assumes according to Rebbe Meyer we don’t say מכלל לאו אתה שומע הן, so we see it’s just a straight din that we don’t assume מכלל לאו אתה שומע הן.  However, if that is the case, what it the reason of the Gemorah in Shevous’s difference between issur and monetary issues, that only regarding monetary issues Rebbe Meyer doesn’t hold of מכלל לאו אתה שומע הן?  Possibly, we can understand in light of Tosfos in many places (ex. Kiddushin 6b) that Rebbe Meyer agrees if there is an אומדנא דמוכח that you don’t need a תנאי כפול.  How is this possible if Rebbe Meyer doesn’t hold of מכלל לאו אתה שומע הן?  The peshat is that Rebbe Meyer also agrees there is reason to assume מכלל לאו אתה שומע הן but its not strong enough to affect a din.  However, if it’s completely obvious that you mean מכלל לאו אתה שומע הן, then even Rebbe Meyer agrees there is no need to spell it out.  Based upon this, we can understand that the bar of birrur necessary to affect a din is higher regarding monetary issues more than issur.  This approach may be the peshat in Tosfos (Shevous) that Rebbe Meyer agrees regarding a harsh issur that we don’t say מכלל לאו אתה שומע הן.  What is the difference if it’s a harsh issur?  To initiate a greater issur, you need a greater bar of birrur.

The problem is in other Rishonim.  They all ask why does Rebbe Meyer need כפל regarding נדר, it’s issur?  The Ran Nedarim )16a) says because it’s an issur cheftzah it’s regarded as monetary.  The Ritvah says there may be a loss of money because of the neder.  Why does this manner, we are dealing with issur, the bar of measurement should be the rules of issur, where we rely upon birrurim?