His basic thesis is clear.
He considers piercing a boil and capturing a snake as being a work that is not intended (אינו מכווין) [and must happen and the doer does not want the result] (פסיק רישא דלא ניחא ליה). This answers the question on the Rambam that holds like Rabbi Yehuda that a work that is done not for its own sake as liable and yet permits piercing a boil. [That is put simply: Reb Chaim is saying the Rambam holds by the opinion of the Aruch ערוך.]
What I wanted to mention today is the fact that Reb Chaims brings the Talmud in Pesachim page 25. The most obvious reasons that Reb Chaim brings that Gemara [Talmud] are clear. If you are just skimming the Reb Chaim you can see he is trying to show a different place where the Rambam holds by the Aruch that a work not intended, and is not pleasing to him but what must happen is permitted (פסיק רישא דלא ניחא ליה). You can also see how by this he is showing how the option open to the Rambam was not open to Tosphot. So in fact we do find that when Tosphot has to answer the same question on Shmuel that there is on the Rambam [because Shmuel and the Rambam hold the same concerning work on Shabat] that Tosphot is forced into a real unsatisfying answer.
But the deeper reason Reb Chaim brings that Gemara is to show an important point. That to the Rambam there is such a thing as pleasure that is not intended that must happen that becomes not pleasing when he intellectually does not want it. It is the idea of pleasure reaching him that is against his will that Reb Chaim is concentrating on. This shows that the will nullifies the pleasure. And this is why Reb Chaim mentions the fact that work on Shabat is different from other type of prohibitions. It is Melechet Machshevet (מלאכת מחשבת)-- it has to be thought. Because by this Reb Chaim is able to show that on Shabat even Rava would agree with Abyee.
When I was learning this with my learning partner, he noticed the Rambam at the beginning of laws of Shabat. That Rambam explains what the words "not intended" and "not needed for its own sake" mean. And that is the place that makes Reb Chaim's idea difficult. It seems to me that from what I remember that this was also the question of the Chazon Ish on Reb Chaim. So what I have done here is to answer the questions on Reb Chaim and by means of that to answer the questions on the Rambam.[I hope.] You have to see the edition of Reb Chaim with the comments of the Chazon Ish in the back. I think that once when I glance at it I noticed the Chazon Ish asking the same question as my learning partner on the particular Reb Chaim. I think I have gained some insight into Reb Chaim in this above essay.
[I don't have the Rambam or Reb Chaim here but it seems to me the major question that Reb Chaim was trying to answer on his thesis is that capturing a snake simply does not fit into the regular way the Rambam understands the meaning of not intended. What is not intended about putting the thing into a trap? So you have to answer my above given answer.]
In any case what does Tosphot hold? Either that work not needed for its own sake and work not intended are completely independent, or that if intended it has to be for its own sake.(I.e not completely independent.) That is in the area of not intended it can for its on sake or not. I am not sure.
Later on I read what Rav Shach wrote about this Rambam and he actually answers the Rambam much better than Reb Chaim. I forget what it was but take a look yourself. Mainly I think he was saying the same thing I said originally about that Rambam--certain kinds of work have intention as part of the definition. So צידת נחש is nothing. It is not even a דבר שאינו מתכווין. And the piercing of the boil is not כדרך הרופאים so it too is nothing.
In any case, this is no surprise to me. Rav Shach definitely surpassed Reb Chaim. If yeshivas would be smart they would all run to get the Avi Ezri of Rav Shach.
It seems every Shabat someone looks at this essay thinking I will say something about electricity. If it would be fire then it would be work done not for its own sake. We see in Kritut that fire for its own sake is to make coals. And so if electricity was fire it would be liable to the Rambam who says work done not for its own sake is liable. But it is not fire so that is that. Anyway besides the Rambam all rishonim hold מלאכה שאנה צריכה לגופה פטורה
And besides this I do not believe in looking for new חומרות--restrictions that are not in the Torah..
The path of the Torah is to keep what it says, not make up new stuff. Being anti-Israel is not just common in the religious world but even raised to the level of the most important Mitzvah. I often have trouble distinguishing between the Ultra religious people from Nazis. This is just one of many examples of the infinite distance between the religious and the Torah. I should mention that the yeshiva of Ponovitch raises the flag of Israel on the Israel Independence Day.
In terms of electricity I already wrote about it that it is not fire and it is not fixing a vessel nor building. It is not fixing a vessel nor building since there is a difference between closing a door on Shabat and fixing a door. That is so even though the door when not closed in useless. The whole trouble is not just in adding extra restrictions that are not from the Torah. The trouble is adding extra restrictions takes away attention from things that the Torah actually forbids and also from things that the Torah actually requires.