|Rav Shlomo Zalman Auerbach and Rav Shimon Moshe Diskin|
הרב משה בן הרב מנחם רייניץ ז"ל
רבקה רחל בת ר' מרדכי רייניץ ז"ל
ר' אליהו שמואל בן ר' יוסף זאב קאלא ז"ל
עטל בת ר' שלמה אריה הלוי קאלא ז"ל
נשמותיהם תעלינה מעלה מעלה על כנפי השכינה!
The gemara [שבת י"ט] says that one make not go on a boat into the sea within 3 days of Shabbos. The famous sugya of אין מפליגין בספינה שלשה ימים לפני שבת!!!! AHHHHHHHHHHH-:).
The Baal Hamaor says that the problem is that he might have to be מחלל שבת in order to save his life so we don't permit it within 3 days of Shabbos [maybe more on that another time]. If however it is more than 3 days from Shabbos - Happy sailing!! Bon Voyage!!!
We see that it is permitted to place oneself in mortal danger that would necessitate חילול שבת. This is called מכניס עצמו לאונס which is a very well known and geshmake sugya.
Reb Elchonon explained that this is because פיקוח נפש is הותרה. Since it is הותרה therefore no problemo to place oneself in a situatioin that would require him to break Shabbos because in that case Shabbos is "off". Asked R"E - The Baal Hamoar paskened that one may not circumcise a on Shabbos baby if the hot water that he prepared for the baby spilled and after the Bris he would have to boil more water and be מחלל שבת [known as "אישתפיך חמימי"]. So וייסט אויס [Spanish for "You have a beer. I thirsty". In the last installment we spoke of Cuba, so this info is important... Also if you attend YU whose neighborhood often sounds like Cuba] - one may NOT place oneself in a situation where he will be compelled to break Shabbos. So how do we allow him to go out to sea if we are concerned that he will have to be מחלל שבת???
One Talmid Chochom attempted the following explanation: What is the din for a Goy who is in a life threatening situation - may he break a halacha to save his life? The answer is .... says Rav Shmuel Rozovsky - מותר. Why? Because his mitzvos were only commanded up until and not including פיקוח נפש. Once we get to Pikuach Nefesh he is no longer commanded and anything he needs to do is permitted. So in the case of the boat, it is permitted for him to be מחלל שבת even without a pasuk. Like, complete הותרה. We don't need וחי בהם to push away חילול שבת because Shabbos is only supposed to be kept up until and not including a threat to one's life. But when it comes to SOMEONE ELSES LIFE ,we need the pasuk of וחי בהם to override and be דוחה Shabbos. That is why the בעל המאור says that if the water spills one may not perform the Bris because one may not place oneself in a situation where he will be compelled to be מחלל שבת on the behalf of someone else.
To summarize: For oneself Shabbos is הותרה [as it is for Goyim in the context of their halachos] and for other people Shabbos is דחויה and thus less permissive.
Rav Shimon Moshe Diskin is not convinced by this explanation. The assumption is that הותרה is more permissive than דחויה. Who says? Maybe הותרה with respect to Shabbos is different that הותרה with regard to korbanos [where it is in fact more permissive than דחויה] and means just that one is not obligated to refrain from חילול שבת when life is in danger but not that שבת is "pushed away" as it is if דחויה. It emerges that דחויה is more permissive than הותרה! So if one may not be מחלל שבת when it is דחויה for someone elses life, then CERTAINLY when it comes to one's own life where it is just הותרה.
The issue is really as follows: The gemara never tells us whether Shabbos is הותרה or דחויה and also never reveals how הותרה and דחויה are defined in the context of Shabbos. Many understand these concepts to be similar to the way they are defined in the context of טומאה but that is not at all clear. This has spawned almost an entire literature. Since the issue is so fuzzy, many theories have been advanced. Even the lashon of the Rambam isn't clear. First [שבת ב א] he calls שבת דחויה and then he proceeds to say [ב ב] that when it comes to פיקוח נפש, Shabbos is like a weekday, which sounds like it is הותרה [depending again on how you define הותרה].
If Rav Diskin is correct then the question reasserts itself - How can the gemara permit one to travel in a boat on Shabbos if it will lead to חילול שבת? How is it different than the Bris case of אישתפיך חמימי??