(Mishnah): If Reuven's jug broke in the Reshus ha'Rabim, and Shimon slipped on the water or was damaged by the shards, Reuven is liable;

R. Yehudah says, if he intended (this is explained on 13b), he is liable. If he did not intend, he is exempt.

(Gemara - R. Lazar): They argue about [when Shimon was damaged] at the time that [Reuven] fell, but all agree that [for damage] after he fell, [Reuven] is liable;

(R. Yochanan): They argue about both at the time that he fell and after he fell.

Question (R. Yochanan, against R. Lazar): If he is exempt at the time that he fell, all the more so after he fell! Why is he exempt at the time that he fell? It is because he made Hefker his Nezikin (things that can damage) in Reshus ha'Rabim. (Since this was due to Ones, he is exempt. Likewise he is exempt afterwards!)

A Tosefta (2:4) supports this one, and a Tosefta (2:6) supports this one.

Support (for R. Yochanan - Tosefta): R. Yehudah agrees to Chachamim that if one left his rock or load in Reshus ha'Rabim, and another came and was damaged through them, he is liable, for he is obligated to guard it. (They argue about when he tripped and dropped something. Chachamim obligate, for they hold that tripping is negligence. All agree that one may not make Hefker Nezikin that resulted from negligence.)

And Chachamim agree to R. Yehudah that if one left bottles on the roof to dry, and they fell and broke, and another came and was damaged through them, he is exempt, for he is not obligated to guard them. (Even though he had time to remove them, he is exempt because they fell b'Ones, e.g. an uncommon wind.)

Support (for R. Lazar - Tosefta): If one came with a basket of straw, and inside was a bundle of thorns [and he tripped and it fell] in Reshus ha'Rabim, and another came and was damaged through them, he is liable. R. Yehudah exempts, for so (on this condition) Yehoshua made Yisrael inherit Eretz Yisrael. (We explained this like BINYAN YERUSHALAYIM.)

Inference: Had Yehoshua not made inheritance of Eretz Yisrael contingent on this, he would be liable!

(R. Yehudah said that he is liable only if he intended.) According to R. Yochanan, [this means that] he intended [to keep] his shards. According to R. Lazar [this means that] he intended [to leave them there; it is as if he intended] to damage.

(R. Ze'ira and R. La): R. Yehudah agrees to Chachamim that if one was Mafkir an ox that gored in Reshus ha'Rabim, he is liable. Stationary Nezek (a pit) is unlike moving Nezek.