In the section of insights into the daf, the following appears:
.... Even though the Torah does not require us to save the life of the child that was found in a city populated mostly by non-Jews, the Rabanan do require that we desecrate Shabbos in order to save his life. ....
Could you please cite for me where in the Torah is says that we are not required to save the life of the child that was found in a city populated mostly by non-Jews? I tried to find this on my own, but could not.
Thank you very much.
It does not say this explicitly in the Torah. Rather, it is based on the principle of "Rov." Whenever there is a doubt (in our case, the doubt being the identity of the child), we explore the factors that might solve the doubt, such as any existing majority (so that in our case, since the majority of people in this town are not Jewish, we treat the child as though he is not Jewish). The source for the principle of "Rov" is found in the Torah in Shemos 23:2, as the Gemara tells us in a number of places (see, for example, Chulin 11a).