• Rebbe Eliezer’ opinion that one becomes as tamei as the tamei food he eats

On the previous Daf, Rebbe Eliezer says that one who eats food which is tamei as a ראשון לטומאה becomes himself a ראשון. Similarly, one who eats a שני becomes a שני, and one who eats a שלישי becomes a שלישי. Rebbe Yehoshua disagrees, and says one who eats a ראשון (or a שני) becomes a שני.

Rabbah bar bar Channah relates that Rebbe Eliezer argued: מצינו אוכל חמור מן האוכל – we find (in Biblical laws) that one who eats [tamei food] is [tamei to a] stricter degree than that of the food itself. Namely, the נבילה of a kosher bird is not metamei what it touches, but one who eats this נבילה is tamei and is metamei his clothing while he is swallowing it. ואנו היאך לא נעשה אוכל כמאכל – And we, who decreed tumah on one who eats tamei food, how can we not make one who eats it at least as [tamei] as the food itself!? Rebbe Yehoshua replied that we do not derive anything from the נבילה of a kosher bird, דחידוש הוא – because it is a novelty (since it is not metamei through external touching, but only once it is inside one’s body, the opposite of standard tumah).

• Rebbe Yehoshua holds someone becomes a lesser degree of tumah than the tamei food he ate

Rebbe Yehoshua argues: מצינו שהמאכל חמור מן האוכל - we find (in Biblical laws) that [tamei] food is stricter than one who eats it, because food becomes tamei with a mere כביצה – egg’s volume of food, yet one who eats tamei food only becomes tamei if he eats half a פרס (i.e., two eggs). Therefore, we must also make someone who eats tamei food a lesser degree of tumah than that which he ate (i.e., one who ate a ראשון becomes a שני). Rebbe Elieizer replied that we do not derive laws of tumah from שיעורין – measures required for becoming tamei. Furthermore, if one who eats tamei food must be less tamei than that which he eats, why does Rebbe Yehoshua himself say that one eats a שני becomes a שני?

Rebbe Yehoshua explained: מצינו שהשני עושה שני ע"י משקין – we find that a שני makes other food it touches a שני via liquids, i.e., if a שני touches wet food, the liquid on the surface becomes a ראשון (a unique Rabbinical property of liquids), which in turn renders the food a שני. Since we find a שני making a שני, the same was decreed on one who eats a שני.

• Eating a שלישי of חולין שנעשו על טהרת תרומה disqualifies him from eating terumah

Ulla says that if one eats a שלישי of חולין שנעשו על טהרת תרומה – chullin prepared according to the standards of taharah of terumah, נפסל גופו מלאכול בתרומה – his body is disqualified from eating terumah, because he becomes a שלישי. Ulla is challenged from a Mishnah which teaches that a שלישי לטומאה is נאכל בנזיד הדמע – may be eaten in a stew containing terumah. This stew must be guarded from tumah according to the taharah standards of terumah, to protect its terumah components. If Ulla is correct, that eating a שלישי of חולין שנעשו על טהרת תרומה disqualifies him from eating terumah (because he becomes a שלישי), ספינן ליה מידי דפסיל ליה לגופיה – can we feed him something which will disqualify him as a שלישי? But it is forbidden to be metamei oneself by eating tamei foods!? Ulla answered that this case of stew is different, because it does not contain a כזית of terumah components בכדי אכילת פרס – in the volume he would eat within the amount of time one eats a פרס. Since he would not transgress the full Biblical prohibition of eating tamei terumah, this chullin need not be guarded according to terumah standards.