2,503. The Ramifications of Not Requiring Intention

Hilchos Shechita 2:12

Pursuant to the previous halacha, if a person with congenital deafness, a person lacking mental competence, a minor, someone who is inebriated and confused, or a person overcome by a mania performs ritual slaughter and others see that he did so properly, the slaughter is valid. However, if a knife falls and slaughters an animal on the way down, this is not a valid slaughter even if it the animal was cut properly because Deuteronomy 12:21 says “You shall slaughter,” from which we see that slaughter must be performed by a person, albeit even if he does so unintentionally.

Hilchos Shechita 2:13

Let’s say that there’s a wheel of stone or wood with a knife attached. A person turns the wheel and he puts the neck of an animal or bird opposite it so that it’s slaughtered when he turns the wheel. In such a case, the slaughter is valid. However, if water is turning the wheel and he puts the neck opposite it while it’s turning, then the slaughter is invalid. If a person makes the water flow until the wheel turns, thereby performing slaughter, then it’s valid because it came about through human effort. This only applies to the first turn of the wheel, which was the result of human effort, not to subsequent rotations, which are the result of the water flowing.