Bava Kamma

But in the case of an ox which was altogether Mu'ad no element of Tam could be found in it at all. R. ELIEZER SAYS: NO PRECAUTION IS SUFFICIENT [FOR MU 'AD] SAVE [THE SLAUGHTER] KNIFE. Rabbah said: What was the reason of R. Eliezer? Because Scripture says: And his owner hath not kept him in,  [meaning] that precaution would no more be of any avail for such a one. Said Abaye to him: If that is so, why not similarly say on the strength of the words, And not cover it  that a cover would no more be of any avail for such a [pit]? And if you say that this is indeed the case, have we not learnt, 'Where it had been covered properly and an ox or an ass has [nevertheless] fallen into it there is exemption'?  — Abaye therefore said: The reason of R. Eliezer was as taught [elsewhere]:  R. Nathan says: Whence do we learn that a man should not bring up a vicious dog in his house, or keep a shaky ladder in his house? Because it is said: Thou bring not blood upon thy house. MISHNAH. IF AN OX HAS GORED A COW AND ITS [NEWLY-BORN] CALF IS FOUND [DEAD] NEAR BY, AND IT IS UNKNOWN WHETHER THE BIRTH OF THE CALF PRECEDED THE GORING  OR FOLLOWED THE GORING,  HALF DAMAGES  WILL BE PAID FOR [THE INJURIES INFLICTED UPON] THE COW  BUT [ONLY] QUARTER DAMAGES WILL BE PAID FOR [THE LOSS OF] THE CALF.  SO ALSO WHERE A COW GORED AN OX AND A [LIVE] CALF WAS FOUND NEAR BY, SO THAT IT WAS UNKNOWN WHETHER THE BIRTH OF THE CALF PRECEDED THE GORING  OR FOLLOWED THE GORING,  HALF DAMAGES CAN BE RECOVERED OUT OF THE COW, AND QUARTER DAMAGES OUT OF THE CALF. GEMARA. Rab Judah on behalf of Samuel said: This ruling is the view of Symmachus who held that money, the ownership of which cannot be decided has to be shared [by the parties].  The Sages, however, say that it is a fundamental principle in law that the onus probandi falls on the claimant. Why was it necessary to state 'this is a fundamental principle in law'? — It was necessary to imply that even where the plaintiff is positive and the defendant dubious  it is still the plaintiff on whom falls onus probandi. Or [we may say] it is also necessary in view of a case of this kind: For it has been stated:  If a man sells an ox to another and it is found to be a gorer, Rab maintained that the sale would be voidable,  whereas Samuel said that the vendor could plead 'I sold it to be slaughtered'.  How so? Why not see whether the vendee was a person buying for field work or whether he was a person buying to slaughter?  — Samuel's view can hold good where he was a person buying both for the one and the other. But why not see if the money paid corresponded to the value of an ox for field work, then it must have been purchased for field work; if, on the other hand it corresponded to that of an ox to be slaughtered, then it must have been purchased for slaughter?  — Samuel's view could still hold good where there was a rise in the price of meat so that the ox was worth the price paid for one for field work.