bava kama page 19. The difference how tosphot and ramban understand the gemara.

Even though it is kind of obvious I think I might mention how the Rambam understands the Gemara on page 19 (that is brought here in my previous blog entry). The Rambam I think is the simplest. The Gemara says, “If there is a question about warning, that automatically implies there is no change.” Then the Gemara turns that around, and says that change is, in fact, in doubt. However, on the side that there is no doubt, there must be a question about warning. The Rambam understands that that is simply in order to change the direction of causation. However, the basic premise stands. That means according to the Rambam, that if there is warning, there can be no change. There can only be doubt about one, or the other. They are variables that are exclusive. To Tosphot the understanding of the Gemara is thus. If there is doubt about change, there can be no warning. That is, that warning and change are mutually dependent variables. If there is warning about pebbles according to their regular way, there must be warning about change also. If there is no change., there cannot be warning about warning when pebbles come their normal way. I might mention thar רב שך has a different interpretation of the רמב''ם that is more in line with תוספות, but not exactly. According to רב שך, the רמב''ם understands the questions of warning or change are exactly the same question. That means, if warning applicable, then there is change. That means damage by foot of an ox has changed to damage by horn of an ox, and so automatically warning is applicable. But if warning does not apply, that means that צרורות remain a derivative of damage by foot, and therefore change can not apply. Change is only applicable to damage by horn.]