It seems that to shut up and multiply, an altruist/rationalist needs to accept a non-obvious axiom that each person's joy or suffering carries equal weight regardless of proximity to the altruist. I for one refuse to accept this axiom because it's immoral to me; think about it.

I have the exact opposite intuition. It is not obvious at all to me that the closeness (emotionally or physically) to someone changes the weight of their suffering. If someone is going to get their fingers slammed in a door, then it matters not should I know them personally or be a thousand light years distant.

Admittedly, I may have a slightly more visceral reaction if someone I know gets in a car wreck than looking at the statistics, but I disagree that means it is Right for me to prevent that car wreck of someone close, only to thereby cause another and in addition lead someone to stub their toe.