Toharot, Chapter Four, Mishnah Eight
Today’s mishnah begins to explain cases of doubtful uncleanness that the rabbis rule pure.
1) “A doubt concerning an object of uncleanness that floated upon water:”
2) [It is clean] whether the water was in vessels or in the ground.
a) Rabbi Shimon says: if in vessels he is deemed unclean but if in the ground he is deemed clean.
3) Rabbi Judah says: if the doubt arose when the man went down into the water he is deemed unclean, but if when he came up he is deemed clean.
4) Rabbi Yose says: even if there is only enough room for a man and the uncleanness the former remains clean.
Section one: There is an unclean object floating on some water and there is doubt as to whether a person touched it. Since the object of impurity does not “have a set place,” the person who might have touched it is pure. We have seen this principle before in mishnah three.
Section two: The first opinion holds that it does not matter whether the object was floating in water on the ground, let’s say in a pond, or in water in a vessel. In both cases it is considered to not have a fixed place. Rabbi Shimon says that if the water is in a vessel then we consider the impure thing to have a place, because the vessel is set in a specific place.
Section three: Rabbi Judah notes that when a person gets into water and there is something floating in the water, it is normal for the thing to come closer and even touch the person. Thus, if the doubt arose when he was getting into the water, he is impure. But when someone gets out of water, it is normal for things to move away from him. Thus in this case the person is pure.
Section four: Rabbi Yose rules that even if there is only enough room in the water for the person and the object, thereby making it quite likely that the person touched the object, the person remains clean. Note that he seems to simply apply the rulecases of doubtful uncleanness where the impurity is moving are pure. This is a legal truth even if it doesn’t seem to be realistic.