That is, instead of responding to a post like this by encouraging people to ...

how about answering with "hey, you know what would be really, really helpful?" and proceeding to list some awesome utility-maximizing charity.

No, no, NO! I desire to correct a fundamental mistake that is counter to whatever good 'rationality' may happen to provide. Raising the sanity waterline is an important goal in itself and particularly applicable in rare communities that have some hope of directing their actions in a way that is actually effective. Not only that, but seeing the very concept of rationality abused to manipulate people into bad decision making is something that makes me feel bad inside. Yes, it is the opposite of a warm fuzzy.

Look, scoffing at less-than-optimal philanthropy is ultimately just another form of counterproductive negativity. If you're really serious about efficacy, you should be adding to the list of causes, not subtracting from it.

You are fundamentally wrong and the use of labeling things that disagree with you as 'negative' is non-rational influence technique that works in most places but should be discouraged here. It is not counterproductive to not do things that are stupid. It is not intrinsically better to add things to a list of normatively demanded behaviors while never removing them. If the list is wrong (for a given value of wrong) then it should be fixed by adding to it or removing from it in whatever way necessary.

Warm feelings are good. Someone who donates a few spare frequent-flyer miles to help Curt Knox and Edda Mellas visit their daughter imprisoned 6,000 miles away doesn't need to feel ashamed of themselves for not being "rational" -- except in the extremely unlikely event that that action actually prevented them from doing something better. Does anyone honestly, seriously believe that discouraging people from doing things like this is a way of making the world a better place?

People being manipulated into actions by the inclusion of irrelevant things in the definition of 'rational' is what I am discouraging. Tell people that Knox is a good way to purchase warm fuzzies, that's fine. But don't dare try to call it a 'challenge for rationality', piggybacking on the human instinct to avoid the shame of not supporting the tribal value ('rational').

Speaking of challenges for LW, I propose a new rule: anybody who comes across an ostensibly good cause, but scoffs at its suboptimality, or thinks "well, it's not that I'm not willing to sacrifice $10, but surely there are better uses of that money" should be immediately required, right then and there, to donate that $10 to the Singularity Institute -- no ifs, ands, or buts.

No ifs and buts? Not everyone here needs to consider the SIAI to be the best use of their money. That's not required by 'rationality' either. You're in the wrong place if you think that approach is at all appropriate. Don't try to force your obsession with Knox on everyone else. It's not my priority and for most people it just isn't the rational way to maximise their preferences either.