Gemara

(Mishnah): Man is always Mu'ad, whether he damaged Shogeg or Mezid (with or without intent), awake or asleep;

27a (Rabah): If one fell off a roof in an abnormal wind and damaged, he pays Nezek, but not the four damages.

48a (Rava): If Shimon entered Reuven's yard without permission and Reuven damaged him, he is exempt.

(Rav Papa): If Reuven knew that Shimon was there, Reuven is liable.

(Rava or Rav Papa): If two people were both acting in a permitted way or both in a forbidden way and Heziku each other, they are liable. If Huzku (they got hurt) through each other, they are exempt.

112a (Rava): If Reuven borrowed a cow and died, and his children thought it was their father's and slaughtered and ate it, they pay a discounted price for the meat (two thirds of the standard price).

Bava Metzia 82b (Beraisa - R. Meir): If Reuven was transporting a barrel, and broke it, whether he was a Shomer Chinam or Shomer Sachar, he swears (that he was not negligent, and is exempt);

R. Yehudah says, a Shomer Chinam swears. A Shomer Sachar must pay.

Makos 7b (Beraisa #1): If one was ascending a ladder and the rung fell, he is liable.

(Beraisa #2): He is exempt.

Opinion #1: Both consider this to be Aliyah. Beraisa #1 obligates for damages (if the victim did not die). Beraisa #2 exempts from Galus.

Opinion #2: Both Beraisos discuss Galus. In Beraisa #1, the rung was wormy (it sags down when he steps on it. This is considered Yeridah). In Beraisa #2, the rung was strong.

Rishonim

Rambam (Hilchos Chovel u'Mazik 1:12): If one fell off a roof in an abnormal wind, he pays Nezek, but not the four damages.

Magid Mishneh: If it was total Ones he is exempt.

Magid Mishneh (16): Rav Papa taught that if two Huzku, i.e. they were damaged by one another, they are exempt. Meforshim derive from here that one is exempt for damage through total Ones.

Rambam (6:1): If one damaged another's money, whether he was Shogeg or Anus, it is as if he was Mezid. If one fell off a roof and broke Kelim, or tripped when walking and fell on Kelim and broke them, he pays full damage.

Magid Mishneh: The Meforshim exempt for total Ones. The Rambam did not distinguish. The Rambam himself exempts one who tripped in some cases (Hilchos Nizkei Mamon 13:5).

Kesef Mishneh: The Rambam (Halachah 4) exempts one who fell from a strong ladder, and the Magid Mishneh himself explains that this is because it is total Ones!

Drishah (CM 378:1 DH v'Da): The correct text of the Magid Mishneh does not 'Lo Chilek' (the Rambam does not distinguish), rather, 'Lo Cholek' (he does not disagree), i.e. also he exempts total Ones. The Beis Yosef cited this text of the Magid Mishneh, therefore he did not question it.

Rambam (4): If one was ascending a ladder and a rung slipped out and he fell and damaged, if the ladder was strong and firm and the rung slipped or became wormy he is exempt, for this was b'Yedei Shamayim.

Question (Ra'avad): Why is this Ones different than falling in an abnormal wind, or sleeping? The Gemara connotes that if it was not wormy. it was Ones. If it was wormy, it was not Ones!

Magid Mishneh: The Rambam's text in Makos 7b said that both Beraisos discuss damages. In Beraisa #2, the ladder was strong and firm. He is exempt, for this is total Ones. An abnormal wind is not such a total Ones.

Bach (CM 378 1 DH u'Mah she'Chosav Rabeinu): The correct text of the Rambam exempts if the ladder was strong and firm and the rung slipped and did not become wormy.

Rosh (3:1): Even though man is always Mu'ad, he is exempt for a great Ones, like breaking a jug in the dark. The Yerushalmi exempts one who slept for damage to one who came afterwards and slept next to him. If a man borrowed a cow and died, and his heirs did not know that it was borrowed, and slaughtered it, they are exempt (they pay only what they benefited from it). If a man carrying a beam in Reshus ha'Rabim stopped, and a man in back of him carrying a pole broke the beam, he is exempt. If one did not know that someone returned his Reshus, and damaged him, he is exempt. f one transporting a barrel broke it, R. Yehudah says that a Shomer Chinam swears, but a Shomer Sachar must pay. He does not obligate due to a man who damaged. This shows that one who damages is exempt for an Ones like theft or loss (for which a Shomer Sachar pays).

Question: One who falls in an unusual wind is liable, even though it is an Ones like theft or loss! If a Shomer guarded an animal using a fence that can fall in an abnormal wind, a Shomer Chinam is exempt, but a Shomer Sachar is liable!

Answer (Rosh): Falling in an unusual wind is a small Ones, like losing something. One who damaged is liable for such an Ones. R. Yehudah holds that tripping is a bigger Ones, like something that was stolen. One who damaged is exempt for such an Ones.

Poskim

Shulchan Aruch (CM 378:1): If one damaged another's money, he pays full damage, whether he was Shogeg or Anus (Rema - this is only if he was not totally Anus, like will be explained). If one fell off a roof and broke Kelim, or tripped when walking and fell on Kelim and broke them, he pays full damage.

Beis Yosef (DH umi'Kol): If one fell in an abnormal wind, the Tur exempts him, i.e. even from Nezek. Rava said that he pays Nezek! Those who exempt for total Ones must say that an abnormal wind is not total Ones.

Shach (1): The Shulchan Aruch means to say that some obligate only if it is not total Ones. It seems that the Rambam and Tur do not distinguish.

Shach (2): One who intentionally damaged is liable even if it was total Ones, e.g. someone was pursuing him to kill him, and he broke others' Kelim (380:3).

Shulchan Aruch (2): If one fell off a roof and injured, he pays full damage, whether he fell in a normal or abnormal wind (Rema - for this is not called total Ones).

Shulchan Aruch (3): If one was ascending a ladder and a rung slipped out and he fell and damaged, if the ladder was strong and firm and the rung slipped or became wormy he is exempt, for this was b'Yedei Shamayim. The same applies to all similar cases.