Shabbos 130-131 Shabbos מכשירי מצוה ,Corona,and drawing the line
Our Daf starts a new Mishna and a new chapter, but it is connected to the last Mishna of the previous chapter which taught that all actions that form an essential part of the process of מילה  (circumcision,) may be performed on shabbos, when the bris is performed on time, namely on the 8’th day.
In this Mishna, Rabbi Eliezer, and Rabbi Akiva dispute to what extent this permission goes.
Rabbi Eliezer goes further than the previous mishna, and rules that not only may one perform all essential parts of the circumcision process, but also preparations for the process, such as bringing the knife through a public domain, or even cutting wood to burn into coals in order to burn the knife before use, if one did not do so before shabbos.
Rabbi Akiva, on the other hand, rules that any preparation that could have been done before shabbos, may not be done on shabbos, and only things which could not be done on shabbos, may be done on shabbos.
Rashi explains that Rabbi Akiva holds that only things that are directly part of the circumcision process may be done on shabbos, seeing as the process itself can only be done on shabbos, but things are preparatory to the process, known as מכשירי מילה , may not, seeing as they can be done before shabbos.
It seems from the way that Rabbi Akiva makes this distinction, that he limits  the definition of the circumcision process itself to things which can only be done on the day of the circumcision, and considers everything else to be in the category of מכשירי מילה  (preparation for the circumcision process), which is not permitted.
On Daf 131a, Rabbi Eliezer goes further and incredibly extends this permission to transgress shabbos in order to prepare for   most other  mitzvot that apply biblically on shabbos, such as lulav, matza, and shofar, though not for writing tefillin and mezuzot!
We have a similar debate regarding performing melacha for food purposes on Yom-Tov (Megila 7b)- The Tana Kama holds that that one may only do melachot that are part of the food preparation itself, such as slaughtering an animal or lighting a fire, but not to source or prepare objects needed for this process, such as sharpening a knife or chopping wood.
In contrast, Rabbi Yehuda holds that one may even perform מכשירי אוכל נפש, melachot need to prepare for the food-preparation process on Yom-Tov.
Unlike Rabbi Eliezer regarding מכשירי מילה, though, Rabbi Yehuda limits this leniency to preparations that could not be done before Yom-Tov.
Later in our perek (Shabbos 137b,) the Gemara indeed says that Rabbi Eliezer holds like Rabbi Yehuda but goes even further than him and permits even preparations that could not be done before-hand.
All these opinions based themselves on Pesukim, and it is not clear that the two debates are logically connected to one another but let us at least examine the possibility that these are indeed connected conceptually.
According to Rabbi Akiva regarding מילה and the Tana Kama regarding Yom-Tov, only things directly part of a normally forbidden action that has been permitted by the Torah, are included in the permission. According to Rabbi Eliezer regarding מילה   and Rabbi Yehuda regarding Yom-Tov, even preparatory actions for the permitted act are allowed.
How do we determine whether it is part of the action, or simply preparatory?
According to Rabbi Akiva, Things which can be done only on the day of the permitted action itself, are considered part of the action itself and permitted, whereas things that can be done the day before are not considered part of the action itself, but rather preparatory to the action, and may not be done.
Rabbi Eliezer either agrees that things that can be done before shabbos are not considered part of the action, but rather preparations, but permits preparations too, or holds that even preparations that can be done before shabbos are considered part of the permitted action and may thus be done.
Regarding yom-Tov, the debate seems somewhat different.
Both Chachamin and Rabbi Yehuda agree that actions  preparatory to the food production process  that could have been done before Yom-Tov  are not permitted, and both agree that things that could not be done before Yom-Tov, are considered preparatory and not part of the actual food production process.
Their argument is not about what is considered part of the actual process and what is only considered preparatory, but only about whether such preparations that can only be done on Yom-Tov are permitted on Yom Tov , and is based on how they interpret the pesukim in that context.
whatever we conclude, in both cases, we see that the more stringent opinions draw the line long before the more lenient opinions in terms of the scope of what the Torah permits.
This is not surprising, as if this were not done, one leniency could lead to another, and one could land up spending the whole shabbos or Yom-Tov doing melacha.
If we follow Rabbi Yehuda and permit מכישירי אוכל נפש that can only be done on shabbos, what is to stop us permitting מכשירין דמכשירין (preparations for preparations) or permitting מכשירין that can be done before shabbos?
Yet despite this concern, the view of Rabbi Yehuda was accepted on Yom-Tov, whereas the extreme leniency of Rabbi Eliezer on shabbos was not. (see relevant sugyos)
Once again this seems to be based primarily on his status as a שמותי, explained by Rashi to mean either of the school of Beit Shamai, which we do not follow, or someone in שמתא (excommunication,) due to his refusal to accept the majority view of Sanhedrin in the famous argument over the stove of Achnai (Bava Metzia 59b.)
Yet there are times that despite this, we do rule like Rabbi Eliezer, and perhaps there is also an underlying logical reason his view was rejected as well.
Perhaps, the slippery slope is indeed a factor here- if we go so far as to allow one to cut wood in order to burn coals in order  to  forge a knife, which he indeed permits, what is to stop us allowing a person to perform any melacha in order to get paid in order to buy the knife, effectively destroying the entire shabbos?
Even in matters of pikuach nefesh, and avoiding dangerous situations, we have seen that Chazal have drawn the line at certain points.
Where the chances of danger to life are negligible and there is no limit to how much melacha one can do to avoid such negligible chances (like running around killing wasps on shabbos,) Rav Huna places limits on pikuach nefesh (Shabbos 121b.)
When an everyday activity that involves a small risk has been accepted by society as a normal part of life (דשו בו רבים ), we have seen that such risks can become halachically acceptable- if we don’t draw a line somewhere, we would need to spend all day locked at home forever, and even that has its dangers(Shabbos 129b.)
Every leniency or stringency must be constantly balanced in order to prevent other key values from being unproportionally affected, and to prevent a slippery slope.
During the current Corona plague, we are constantly faced with the question of how far to go to contain it.
If we go to far, we can land up stopping normal living entirely and create even greater economic, social, educational, spiritual and psychological dangers.
If we do not go far enough, we risk countless deaths and the ultimate destruction of the health system and economy as well.
For example, when we give people space to go out as long as they keep a 2 meter distance between one another and wear masks, they decide that they do not need to wear masks if they keep a distance, or to keep a distance when they are wearing masks.
Some decide that neither precaution is necessary.
When we open schools with no distancing on condition that masks are worn, we land up relaxing the need for masks when the weather is too hot, and that causes the next wave of the plague.
The Torah always implores us to strike the right balance, and Chazal are tasked with working out exactly where and how it does so. We need to try and do our best to follow their example.