The essay is here: http://lesswrong.com/lw/3k/how_to_not_lose_an_argument/
Isn't calling rhetoric "the dark arts" using the exact tactic you are advocating against?
I like your idea, but I think it is incomplete. First, I don't like the way you demonize rhetoric. Before labeling rhetoric the "dark arts" I think it needs to be proven that it is truly fact and not rhetoric that convinces people of what is rational. Secondly, I do not think convincing someone that the universe can be moral without God is a a proper line of flight.
In regards to my first critique, I think there is a false dichotomy being draw between reason and value. I do not know how this idea will be received on a radically rationalist blog, but as far as I know no one has yet to prove that reasons can escape values. If you are aware of such an essay/ body of work, please let me know about it, though I do not see how you could ever remove rhetoric from communication. For example, the problem I have in your reasoning about the reassurance of a moral universe is one with your rhetoric.
Basic to the science of rhetoric is the idea that audience determines the nature of the argument. Audience can be interpreted as context. The context of the debate determines what is correct and what is false. You see convincing a theist of the morality of a non-theistic universe as leaving them a line of flight. The assumption that you are making, is that what is at stake for the theist is the issue of morality. The issue of existing in a moral vs. amoral universe is a transcendental one. Likewise, God is a transcendental topic. The problem with your reasoning is that just because God is a transcendental topic does not mean that a theists belief in God is for transcendental reasons. For example, a belief in God not only represents "God", it represents a history, a culture, a family. How can you say that a person’s belief in God is the primarily of transcendental concern as opposed to filial concern (meaning believing in God because of a stronger belief in ones father or mother)?
As of now I cannot claim to have a perfect method of knowing the correct value base of a person's belief, but I am certain that there are people who are theists not for transcendental reasons, but for cultural or personal ones. Let's pretend that it is one of those people that your are trying to correct of their fundamentalist flaws.
If you convince a person that the universe is still moral without God is that going to give them a line of flight? No, it will not. They can either: A.) except that God exists or B.) Except that their parents and loved ones were stupid and wasted their lives believing in something stupid (which would imply that they were raised stupidly). How is this any less damaging to the ego than the alternative you proposed? It isn't.
Please do not misinterpret my meaning. I am strongly in favor of rationalism. I just don't find it rational to deny the irrationality of social existence. Rhetoric and solidarity are more fundamental to human existence that rationality. I am all for increasing rationality, but not in order to eliminate values.
I am not suggesting that we should tolerate everything. There are bad ideas out there, religious fundamentalism is one of them. I like your idea of leaving a line of flight. My suggestion would be that the line of flight must take into account a base level of irrationality. For example, rather than getting rid of God, I think we should redefine God. There are plenty of theologians who are working to do just this. Religion serves a purpose. That purpose is not to define the empirical world or provide a totalitarian mantra of action and thought. Nothing should do these things, not even science. What we need is not to eliminate religion, but to rectify what it means. The same is necessary for science and for logic. A scientific fundamentalist and a mathematical fundamentalist are just as dangerous as a religious fundamentalist.
