notsonewuser, a precondition of rational agency is the capacity accurately to represent the world. So in a sense, the local witch-doctor, a jihadi, and the Pope cannot act rationally - maybe "rational" relative to their conceptual scheme, but they are still essentially psychotic. Epistemic and instrumental rationality are intimately linked. Thus the growth of science has taken us all the way from a naive geocentrism to Everett's multiverse. Our idealised Decision Theory needs to reflect this progress. Unfortunately, trying to understand the nature of first-person facts and subjective agency within the conceptual framework of science is challenging, partly because there seems no place within an orthodox materialist ontology for the phenomenology of experience; but also because one has access only to an extraordinarily restricted set of first-person facts at any instant - the contents of a single here-and now. Within any given here-and-now, each of us seems to be the centre of the universe; the whole world is centred on one's body-image. Natural selection has designed us -and structured our perceptions - so one would probably lay down one's life for two of one's brothers or eight of one's cousins, just as kin-selection theory predicts; but one might well sacrifice a small third-world country rather than lose one's child. One's own child seems inherently more important than a faraway country of which one knows little. The egocentric illusion is hugely genetically adaptive. This distortion of perspective means we're also prone to massive temporal and spatial discounting. The question is whether some first-person facts are really special or ontologically privileged or deserve more weight simply because they are more epistemologically accessible? Or alternatively, is a constraint on ideal rational action that we de-bias ourselves?

Granted the scientific world picture, then, can it be rational to take pleasure in causing suffering to other subjects of experience just for the sake of it? After all, you're not a mirror-touch synaesthete. Watching primitive sentients squirm gives you pleasure. But this is my point. You aren't adequately representing the first-person perspectives in question. Representation is not all-or-nothing; representational fidelity is dimensional rather than categorical. Complete fidelity of representation entails perfectly capturing every element of both the formal third-person facts and subjective-first-person facts about the system in question. Currently, none of us yet enjoys noninferential access to other minds - though technology may shortly overcome our cognitive limitations here. I gather your neocortical representations sometimes tend causally to covary with squirming sentients. Presumably, their squirmings trigger the release of endogenous opioids in your hedonic hotspots, You enjoy the experience! (cf. http://news.nationalgeographic.com/news/2008/11/081107-bully-brain.html) But insofar as you find the first-person state of being panic-stricken as in any way enjoyable, you have misrepresented its nature. By analogy, a masochist might be turned on watching a video involving ritualised but nonconsensual pain and degradation. The co-release of endogenous opioids within his CNS prevents the masochist from adequately representing what's really happening from the first-person perspective of the victim. The opioids colour the masochist's representations with positive hedonic tone. Or to use another example, stimulate the relevant bit of neocortex with microelectrodes and you will find everything indiscriminately funny (cf.http://news.bbc.co.uk/1/hi/sci/tech/55893.stm ) - even your child drowning before your eyes. Why intervene if it's so funny? Although the funniness seems intrinsic to one's representations, they are misrepresentations to the extent they mischaracterise the first-person experiences of the subject in question. There isn't anything intrinsically funny about a suffering sentient. Rightly or wrongly, I assume that full-spectrum superintelligences will surpass humans in their capacity impartially to grasp first-person and third-person perspectives - a radical extension of the runaway mind-reading prowess that helped drive the evolution of disjunctively human intelligence.

So, no, without rewiring your brain, I doubt I can change your mind. But then if some touchy-feely superempathiser says they don't want to learn about quantum physics or Bayesian probability theory, you probably won't change their mind either. Such is life. If we aspire to be ideal rational agents - both epistemically and instrumentally rational - then we'll impartially weigh the first-person and third-person facts alike.