But I’ve changed my mind TB Shabbat 91

Although we know that there are 39 different prohibited labors, massechet Shabbat spends an inordinate amount of time analyzing the prohibition of moving an item from one domain to another, hotza-ah הוצאה. The messechet’s first chapter introduces the topic of hotza-ah. We learned in the seventh chapter that the item under consideration needs to be significant both in quality and quantity to violate the prohibition of hotza-ah. Chapter 8 gives the minimum measurements of different items a person needs to move from one domain to another to be liable. After several pages of Aggadah, the last several mishnayot of chapter 9 returns to the topic of different measurements for more items. We learned that the common usage and utility of the item also impacts its measurements.

Today we begin chapter 10 with daf TB Shabbat 91 (really at the very bottom of TB Shabbat 90b). This chapter deals with more of a conceptual approach of the ins and outs of the prohibition of hotza-ah. For example what happens if you change your mind? At first you carried the item from one domain to another intending to do one of the prohibited activities, but in the middle you change your mind to use the object for completely different prohibited activity. What impact if any does changing your mind have? Are you guilty (חייב) and need to bring a sin sacrifice or freed from bringing that sacrifice (פטור)? Rav Nahman gives us the answer to our question.

“Rava said that Rav Naḥman said: If one carried out on Shabbat a dried fig-bulk of seeds for eating, and along the way he reconsidered and decided to use them for sowing; or, alternatively, if one intended to carry them out for sowing and reconsidered and decided to use them for eating, he is liable. The Gemara wonders: This is obvious. Whichever way you view this case, he is clearly liable. Go here and examine his initial intention, there is a measure that determines liability; and go here and examine his ultimate intention, there is a measure that determines liability. The Gemara replies that Rav Naḥman’s statement teaches a novel concept. Lest you say that in order to be deemed liable for carrying out an object on Shabbat, we require that the lifting and placing of the object be performed with a single, identical, intention, and that is not the situation here, i.e., that the change in his intention transforms his action into two separate half-labors, therefore Rav Naḥman teaches us that it is considered a single prohibited act, and the person who performed it is liable.” (Sefaria.org translation)

In this case changing your mind doesn’t help you at all.