A or B: which reason is the real one?

In his words

There's a lot of Gemaras that ask questions, in this situation, is it A or B? 3:43 The method is to hold both reasons, project each onto the new case, and see that they give different rulings. If the reason is importance, valuable sesame seeds must be returned; if it's bother, sesame seeds are even more bother, so the finder keeps them.

Sometimes the Gemara never decides. He explains that when it's this kind of question ("is it this or is it that?") the Gemara often ends with teiku.

Worked example from a class

He has the class read back the two sides of the sesame-seed question from their explanation sheet (29:45), then do dates and pomegranates, where the two reasons again point opposite ways (49:05).

Hear him teach it

78 moments found so far in 77 transcribed classes; more appear as transcription continues. Tap one to play from that moment.

1. Westwood · Beginner class, Nov 16, 2011 · 3:43“There's a lot of Gemaras that ask questions, in this situation, is it A or B? And then they'll say, it's A, or it's B.”Explains the form of Rabbi Yirmiyah's question, A or B, left without an answer.
2. Westwood · Beginner class, Nov 21, 2011 · 14:15“comma by going back And, trying to determine why a person may keep one calf of wheat”He projects the two possible reasons for the base case (bother or unimportance) onto dates and pomegranates.
3. Westwood · Beginner class, Jan 9, 2012 · 56:09“Because they were saying their opinion as if they were the ones to originate it.”A dispute between Tannaim refutes both Amoraim, because each claimed the other view could not exist.
4. Westwood · Beginner class, Feb 15, 2012 · 7:03“Here's a Braisa, you can either explain it A or B, and we don't know which way is right and which way is wrong, because they both work”Two possible readings of the Braisa: one proves Abaye, the other makes the Braisa irrelevant to the dispute.
5. Westwood · Beginner class, Feb 20, 2012 · 21:51“So then there's a certain predictability of what it should say. And if it doesn't say that, that means we got to go and re-examine our thinking.”Project each explanation (can save later or cannot) onto the seifa and see which one fits.
6. Westwood · Beginner class, Feb 27, 2012 · 44:07“That's why we're exposing the end of the Braisa, not so much to the end of the Braisa, but to go back in the beginning of the Braisa”Projecting each of the three explanations onto the end of the Braisa to see which ones survive.
7. Encino, Mar 20, 2012 · 52:02“What happens if I find something which might be a sign, but it might not be a sign? Depending on how it got in there.”Frames the dispute as whether a doubtful siman must be treated strictly.
8. Encino, Apr 17, 2012 · 41:30“So we're trying to figure out what the case is talking about and it seems like we exhausted either they fell or someone put them there.”Tests both possible scenarios against Rabbi Yitzchak's measure, and both fail.
9. Encino, May 8, 2012 · 37:16“Depending on the reason will depend on the outcome of a half a kav in two amos.”Projects each of the two reasons (bother vs importance) onto the new case.
10. Encino, May 22, 2012 · 11:34“so if you're going with bother, you would be allowed to keep it, if you're going with value, then you would not be allowed to keep it”Projects each candidate reason onto the new case to see that they lead to different rulings.