Niddah

Our Rabbis taught: If a pigeon  fell into a winepress  and it was intended to pick it up for a Samaritan,  it is unclean;  but if it was intended for a dog it is clean,  R. Johanan b. Nuri  ruled, Even if intended for a dog it is unclean.  R. Johanan b. Nuri argued: This is arrived at a minori ad majus. If it  conveys a major uncleanness,  though there was no intention,  should it not convey a minor uncleanness  though there was no intention? They answered him: No; if you maintain your view in the case of a major uncleanness, which never descends to that,  would you also maintain it in the case of a minor uncleanness which does descend to that?  He replied: the hen of Jamnia proves my contention, for it descends to that and, though there was no intention, it was declared unclean. 'From there', they retorted, 'is your proof? In that place there were Samaritans and it was intended that they shall eat it.' Now with what case are we dealing here? If it be suggested with big cities [the objection would arise]: What need was there for intention, seeing that we have learnt: The carcass of a clean beast anywhere  and the carcass of a clean bird and forbidden fat in large towns  require neither intention nor to be rendered susceptible.  If, however, it is suggested: Of villages, [the difficulty arises:] Is there any authority who maintains that in this case no intention is required, seeing that we have learnt: The carcass of an unclean beast  anywhere  and the carcass of a clean bird in villages  require  intention  but need not be rendered susceptible?  — R. Ze'ira b. Hanina replied: We are in fact dealing with an incident in a big city, but  the winepress caused it  to be objectionable  and thus caused the town to be regarded as a village. 'R. Johanan b. Nuri argued: This is arrived at a minori ad majus. If it conveys a major uncleanness, though there was no intention, should it not convey a minor uncleanness though there was no intention? They answered him: No; if you maintain your view in the case of a major uncleanness which never descends to that.' What is meant by 'it never descends to that'? — Raba replied: It is this that they  in effect said to him,  'No; if you maintain your view