The ran brings the question of the first tosfos on the masechta that what's the point of bedika medrabban if bittul is sufficient ? (Meaning acc to rashi what the point of Gezeiras Bedikah d'Rabanan) but then he goes to answer a whole diff question of that bittul and bedik both work mi'd'Oraisa.
But that wasn't the question the qeustion was why did the chachmim want u to make a bedika on top of the bittul and u see that he actually asks in the Chiddushei haran the question he asks here and then he Catullus give tosfos answer that u might come to eat then what is he asking in the first question
Mordechai yusupov, Queens, New York
The Ran starts with the question of Tosfos that what is the point of bedikah if anyway one has to do bitul, but then he answers that mideoraisa either bitul or bedikah is sufficient but miderabanan there is a good reason to require both. He also writes this in Chidushei Haran; that some answer this question by saying that mideoriasa either bitul or bedikah is sufficient.
Shabbat Shalom and Pesach Kasher veSameach and besorot tovot!
Dovid Bloom
Follow-up reply:
First, I must apologise for the above short reply, which by no means at all does justice to this very thoughtful question. To be honest I did not read the question carefully enough, but now I have looked at it more thoroughly.
1) We start with Rashi, bs'd. It may be that according to Rashi there is not in fact a Gezeiras Bedikah d'Rabanan. Rashi writes that one checks the chametz so that one will not transgess Bal Ye'raeh and Bal Yimatzei. The simple reading of this is that bedikah is deoraisa. In fact, the Ran on the Rif writes, at the end of the paragraph beginning "Ella", that his shittah that mideoraisa either bitul or beidkah is sufficient, is the way of Rashi. So Rashi's opinion according to the Ran is that bedikah is a Torah Mitzvah if one did not perform bitul.
2) Now to the Ran's question in the name of Tosfos. If we look carefully we see that the Ran does not ask what is the point of bedikah miderabanan if bitul is sufficent? In fact I think you will not find anywhere in the Ran on the Rif, that he writes that bedikah is only derabanan. Again, a close reading of the Ran on the Rif shows us that the question he reports in the name of Tosfos is not the same question that our Tosfos asks in the name of the RI. The RI does indeed ask that since one anyway requires bitul according to the Torah, why is it necessary to do bedikah as well? However the question the Ran asks in the name of Tosfos is different. He asks that since the Gemara 4b states that mideoraisa bitul alone is sufficient, and since the Gemara 6b states that after one does bedikah one anyway also has to do bitul; if so, how can Rashi say that if one does bedikah this prevents you from transgressing the Torah prohibitions?! Since one also has to do bitul, and bitul alone is sufficient, how then can bedikah work mideoraisa?!
3) Again, it is worth noting that when the Ran cites the question of Tosfos he does not say anything about bedikah being derabanan, but rather the question was how can bedikah be strong enough to exempt what it seems that only bitul can exempt?
Must close here for the moment.
Shavua Tov uMevorach
Dovid Bloom
Further analysis of the Ran:
1) Now that we have seen that the Ran on the Rif never said that bedikah is only miderabanan, we can understand his answer to the first question in the name of Tosfos. The question was that since bitul is sufficient mideoraisa, and since one must do bitul, how can bedikah take away the Torah prohibitions of chametz?! On that the Ran answered that either bitul or bedikah are good mideoraisa.
2) Now to the Chidushei HaRan. He starts by asking the same question in the name of Tosfos that he asks in the Ran on the Rif, and basically gives the same answer. It is only then that he asks the question of the RI from our version of Tosfos; that what is the point of bedikah if bitul is sufficient, and on that he gives the answer of RI that you might come to eat it. The difference between the Ran on the Rif and the Chidushei HaRan is that the Ran on the Rif only asks the question of his Tosfos (not our Tosfos) whilst the Chidushei HaRan also asks the question of the RI and gives the answer of the RI.
Pesach Kasher veSameach
Dovid Bloom