Maybe I didn't express it well, but I'm not claiming that some people aren't intrinsically more compassionate (or selfish, or obedient, or any other personality trait) than others, and thus more likely to balk. That I agree with.
What I'm objecting to is that MoR seems to treat feelings as if they were always there and battling to be felt, like the id and superego vying over the conscious mind -- as if people could be compassionate 'underneath' the influence of selfishness. But the brain doesn't work that way: people are compassionate or selfish at any given moment, depending on how their brain fires. One feeling is no more 'real' than another.
To say someone is 'compassionate' is to say that they will feel/act compassionately more often than an average person, because their brain is wired in a way that causes them to experience more compassion. It's a description of behavior, not something that people can be 'inside'.
Update: Discussion has moved on to a new thread.
After 61 chapters of Harry Potter and the Methods of Rationality and 5 discussion threads with over 500 comments each, HPMOR discussion has graduated from the main page and moved into the Less Wrong discussion section (which seems like a more appropriate location). You can post all of your insights, speculation, and, well, discussion about Eliezer Yudkowsky's Harry Potter fanfic here.
Previous threads are available under the harry_potter tag on the main page (or: one, two, three, four, five); this and future threads will be found under the discussion section tag (since there is a separate tag system for the discussion section). See also the author page for (almost) all things HPMOR, and AdeleneDawner's Author's Notes archive for one thing that the author page is missing.
As a reminder, it's useful to indicate at the start of your comment which chapter you are commenting on. Time passes but your comment stays the same.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: