what is the difference between 'instinct' and 'desire'? what is a 'longing'? if you took the children away from the pedophile maybe he watches oprah all day or fantasizes about big macs? how do we know what goes on in the mind of a cat, for us to know there is no 'longing' to cause suffering? chimpanzees live a mostly vegetarian life, but seem to have a 'longing' once in a while to eat monkeys, which they express by hunting them down and killing them. they seek out and kill the monkeys, not just kill monkeys that happen along. how do we define "suffering for suffering's sake" -- the chimpanzee ultimately eats the monkey, so that is not an instance of suffering for suffering's sake? but then a sadomasochist achieves some physical/mental gratificaion by inflicting suffering. what's the difference?
'behaviourism' may have been beaten to death, but does that mean we can now freely use poorly defined terms like 'desire' and 'longing' to make a case? as for assuming self-detrimental positions, members of various species actively do that (i believe wilson/sober's 'unto others' documents a few examples). of course it would be difficult to show that 'conscious personal gratificaiton' is at play rather than 'biological instinct' but that is only because, IMHO, the former words (conscious, gratification, etc) are ill-defined while the latter is not. well, unless you are an out-and-out behaviourist, in which case neither is 'instinct'.
--ravi