As I understand the post, its idea is that a rationalist should never "start with a bottom line and then fill out the arguments".
I disagree. The idea, rather, is that your beliefs are as good as the algorithm that fills out the bottom line. Doesn't mean you shouldn't start by filling out the bottom line; just that you shouldn't do it by thinking of what feels good or what will win you an argument or by any other algorithm only weakly correlated with truth.
Also, note that if what you write above the bottom line can change the bottom line, that's part of the algorithm too. So, actually, I do agree that a rationalist should not write the bottom line, look for a chain of reasoning that supports it, and refuse to change the bottom line if the reasoning doesn't.
In the spirit of contrarianism, I'd like to argue against The Bottom Line.
As I understand the post, its idea is that a rationalist should never "start with a bottom line and then fill out the arguments".
It sounds neat, but I think it is not psychologically feasible. I find that whenever I actually argue, I always have the conclusion already written. Without it, it is impossible to have any direction, and an argument without any direction does not go anywhere.
What actually happens is:
It is at the point 3 that the biases really struck. Motivated Stopping makes me stop checking too early, and Motivated Continuation makes me look for better arguments when defective ones are found for the conclusion I seek, but not for alternatives, resulting in Straw Men.