Why are you liable for eating on Yom Kippur the forbidden designated amount of
food in a scenario where the first half is permissible?
For example if a person is dangerously sick and was told he must eat half an
amount of a thick date of food every 9 minutes. If he eats the full date amount
he is liable though the first half was permissible for him to eat.
A thick date is the amount considered to be enough to compose and settle one’s
mind if he is hungry, which is why it is the amount of liability.
The Torah says one should cause himself to suffer on Yom Kippur.
D. The Kesser Sofer (responsa 31) says that even if a person ate half a date size right before Yom Kippur and another half right after Yom Kippur started he is still liable.
Answer: Even though he was only not allowed to have half of what he ate but because the combo combined to create a state of composer and settling of the mind it then created a liability since that is the exact issue which the Torah forbade. The exact measurement is just the amount designated which causes composer.
Why does the Rambam rely on the majority in this case of Yom Kippur when the
doctors say he does not have to fast but in all other life and death situations
the rule is we don’t rely on majority?
The Rambam (Hilchos shvisas ishur 2:8) poskins that if some doctors say one has
to eat on Yom Kippur because of a life threatening situation and others say he
can fast we go by the majority.
B. The Rambam (Hilchos Shabbos 2:20) says if
there was an apartment building with 1000 non-Jews and 1 Jew and one of them
left the building on Shabbos and went next door to a building that then
collapsed . The halacha is we must go through the building to see if the person
survived since it might be a Jew even if it means profaning Shabbos.
The Gemara in Yoma 84b says we don’t rely on majority in life threatening
D. For the sake of the severity of Shabbos one can only break Shabbos if a Jew, who has the potential to keep future Shabboses, is in life threatening danger.
Answer: By the Yom Kippur case the doctors are making a decision if it is a life threatening case or not therefore one must rely on a majority but by the Shabbos there is clear and present danger therefore we are not allowed to rely on a majority.