Followup to: The Bottom Line
A recent conversation reminded me of this simple, important, and difficult method:
When someone asks you "Why are you doing X?",
And you don't remember an answer previously in mind,
Do not ask yourself "Why am I doing X?".
For example, if someone asks you
"Why are you using a QWERTY keyboard?" or "Why haven't you invested in stocks?"
and you don't remember already considering this exact question and deciding it,
do not ask yourself "Why am I using a QWERTY keyboard?" or "Why aren't I invested in stocks?"
Instead, try to blank your mind - maybe not a full-fledged crisis of faith, but at least try to prevent your mind from knowing the answer immediately - and ask yourself:
"Should I do X, or not?"
Should I use a QWERTY keyboard, or not? Should I invest in stocks, or not?
When you finish considering this question, print out a traceback of the arguments that you yourself considered in order to arrive at your decision, whether that decision is to X, or not X. Those are your only real reasons, nor is it possible to arrive at a real reason in any other way.
And this is also writing advice: because I have sometimes been approached by people who say "How do I convince people to wear green shoes? I don't know how to argue it," and I reply, "Ask yourself honestly whether you should wear green shoes; then make a list of which thoughts actually move you to decide one way or another; then figure out how to explain or argue them, recursing as necessary."
ZMD: I'm reminded of the darcs revision control system and its patch theory. Given patches A and B applied in order (AB), it's possible to calculate two commuted patches A' and B' that when applied in the opposite order (B'A') produce the same result. If you did A, did B, and want to undo A, you commute the patches, and then take A' away from A to walk you back to B'.
That's really only an illustrative analogy, but it's a good one. You could see the algorithm here as "commute the decision to the front and delete it". So taking your example, the original was "decide, and leave, and become an individualist". The commuted version is "leave, and become an individualist, and decide". Then delete the decision. You're re-deciding in the context of the rest of the status quo as a given. "Given I have left and I have become an individualist, would I now decide to leave?".
Thinking of it that way is a bit brain-twisty, but it makes sense.
Are you sure there's supposed to be a B'? It looks to me like you just need to calculate A' = BAB^-1. That way, when you take A' away, you get back to B instead of B'.