Is there anywhere I could read about Anna Salamon's "alternatives procedure" prior to today's meetup?

Where is Eliezer's Metaethics Sequence?

People seem to have a little arrow in their heads saying whether they "believe in" or "don't believe in" a proposition. If there are two possibilities, 50% is the point at which the little arrow goes from "not believe" to "believe".

And if I am following you, this is irrational. Correct?

I second this.