Earlier on (I think it was Rab Yehuda; see Bava Metzia 48b) said that if the seller received 200 Zuz for a field that is sold for 1000 Zuz, he is entitled to that portion of the field that he paid for. In this daf the buyer must pay in full or change the balance into loan. Can you explain the situation
Thank you
Abe Murad, Montreal, Canada
The Gemara (Bava Metzia 77b) asks your question, but the other way around. Rebbi Yehudah (whom you quote) and Rebbi Yossi are arguing over a case where the money was given as a security, which has nothing to do with the basic Din to which you are referring.
The Gemara in Bava Metzia 77b cites Raban Shimon ben Gamliel, from whose ruling we extrapolate that (unless specifically stipulated) if a purchaser does not pay the entire price he does not acquire the field at all (i.e. the seller can retract). The Gemara questions this from another Beraisa, where he himself rules that the purchaser does acquire the entire field, leaving him to pay off the balance in the form of a loan.
To answer the question, the Gemara cites Rava. Rava draws a distinction between where the seller is chasing the purchaser for the money (an indication that he is only selling the field because he needs the money), in which case the purchaser will not acquire the field unless he pays in full, and where the seller is not chasing the buyer for the money, in which case the purchaser acquires the entire field with a partial payment.
be'Virchas Kol Tuv,
Rabbi Eliezer Chrysler