the gemara says that a baby can count as the tenth for a zimun. however on daf 45b the gemara says that when it comes to zimun of 10 we are more machmir bc we mention hashems name therefore we require for the 10th person to come back. so why does a baby count for a zimun by 10? it should count for a zimun of 3 or not at all
Avi Lachman, United States
The Rosh, near the end of #20, writes in the name of Rav Yosef that it is probable that Rabbi Yehoshua ben Levi, who maintains on 47b that a baby can be counted as a tenth for a zimun, agrees with Rav Ashi cited on 45b who maintains that the 10th person who left the group does not have to come back, because 9 looks like 10. Since the Gemara 45b rules according to Mar Zutra against Rav Ashi that the 10th person must come back, it follows that the Halacha does not follow R' Yehoshua ben Levi either.
The 2 opinions from the Gemara that you have cited, Avi, disagree with each other, and Rav Yosef paskens that the baby cannot count as the 10th.
KOL TUV
Dovid Bloom