Discussion 1 to Meditation 558
A spectrum not reflected in reality
It might suit the argument that Dawkins is trying to make to suggest that there is a continuous spectrum of belief from 100% probability of God's existence to 0%. However, in my opinion this is not reflected in the way people actually think.
I suggesr people's beliefs are almost entirely clustered at the two ends of the spectrum. The middle (milestones 3, 4, and 5) is almost empty, and these represent at most the temporary condition of those in transition to one end or the other.
In particular to suggest that only those at levels 3 and 4 (just over 50% and exactly 50% probability of God's existence) are agnostics both misunderstands and misrepresents agnosticism.
I expect to write further on this once I read Dawkins' book (currently in the mail) but I suspect what his chapter covers is not "The Poverty of Agnosticism," but "The Poverty of Dawkins' Understanding of Agnosticism."
However, I have no problem with those who consider themselves both atheists and agnostics. It is just not a position I personally choose to take.