Why, if we may ask the nochri to warm water for the mother, will that help for the baby?
Gershon
What the Gemara means is, that when we ask the Nochri to heat up water for the mother, we will ask him to add a little for the baby, which we would not have been permitted to do otherwise, since boiling water is a Melachah d'Oraysa (refer to the Tosfos cited in Mesores ha'Shas).
be'Virchas Kol Tuv
Eliezer Chrysler.
Why, if we may ask the nochri to warm water for the mother, will that help for the baby?
What the Gemara means is, that when we ask the Nochri to heat up water for the mother, we will ask him to add a little for the baby, which we would not have been permitted to do otherwise, since boiling water is a Melachah d'Oraysa (refer to the Tosfos cited in Mesores ha'Shas).
I thought of that, but isn't ribui beshiurim a de'oraisa on Shabbos?
That must be what Rava meant, and it is the Kashya from 'Marbeh be'Shi'urim', that needs to be addressed.
The Bi'urei ha'Rishonim (at the back of Shas Lublin), cites Tosfos in Gitin (8b) that it is forbidden in a case such as ours, to permit a Yisrael to add water, because it is Marbeh be'Shi'urim, which is Asur min ha'Torah (exactly as you assumed).
Clearly, through a Nochri, it is permitted (despite the fact that it is an Isur d'Oraysa). Bearing in mind that Amirah le'Nochri is in any case, mi'de'Rabbanan, and it is the Chachamim who drew a distinction between whether the Melachah that he is performing is d'Oraysa (Sh'vus) or de'Rabbanan (Sh'vus di'Shevus), we will have to say that just as the Rabbanan permitted Sh'vus di'Shevus be'Makom Mitzvah, so too did they permit asking the Nochri to merely add some water (even though it involves an Isur d'Oraysa), since the initial Melachah is already permitted.
The Ritva however, explains that it is only adding another piece that the Torah forbids, but not adding water to water. That, he maintains, is only Asur mi'de'Rabbanan, in which case your problem is neatly solved.
be'Virchas Kol Tuv
Eliezer Chrysler.
Could it be that we don't actually ask him to add any, but we ask him to warm water, and we either don't tell him an amount, or we assume he will heat plenty.
Presumably this removes the problem of asking the Nochri to do extra Melocho - there would remain an issue of benefiting from the heated water (Nehene MiMaase Akum) - maybe this is easier to deal with for the baby?
Kol Tuv
Meir Eliezer Bergman, Manchester UK
Your answer would certainly be acceptable, if we did not have other answers. And what's more, I agree with your last comment.
Not telling the Nochri the amount however, is not a good idea, since he may heat too little, even for the mother. And even if we tell him what it is for, how can we rely on him heating more? He will probably heat up only as much water as the mother needs and leave us without the means to perform the Milah.
Consequently, seeing as we have other answers, which permit asking the Nochri to heat water for the baby directly, we do not therefore use your answer, which leaves us with problems.
be'Virchas Kol Tuv
Eliezer Chrysler.