joanna,
w.r.t your question about why some reason is needed, you may find the below from fodor amusing:
Thus the joke about the lawyer who is offered sex by a beautiful girl. 'Well, I guess so,' he replies, 'but what's in it for me?'
> The literature of Psychological Darwinism is full of what appear to
> be fallacies of rationalisation: arguments where the evidence offered
> that an interest in Y is the motive for a creature's behaviour is
> primarily that an interest in Y would rationalise the behaviour if it
> were the creature's motive. Pinker's book provides so many examples
> that one hardly knows where to start. Here he is on friendship:
>
> Once you have made yourself valuable to someone, the person becomes
> valuable to you. You value him or her because if you were ever in
> trouble, they would have a stake - albeit a selfish stake - in
> getting you out. But now that you value the person, they should value
> you even more . . . because of your stake in rescuing him or her from
> hard times . . . This runaway process is what we call friendship.'
>
> And here he is on why we like to read fiction: 'Fictional narratives
> supply us with a mental catalogue of the fatal conundrums we might
> face someday and the outcomes of strategies we could deploy in them.
> What are the options if I were to suspect that my uncle killed my
> father, took his position, and married my mother?' Good question. Or
> what if it turns out that, having just used the ring that I got by
> kidnapping a dwarf to pay off the giants who built me my new castle,
> I should discover that it is the very ring that I need in order to
> continue to be immortal and rule the world? It's important to think
> out the options betimes, because a thing like that could happen to
> anyone and you can never have too much insurance. At one point Pinker
> quotes H.L. Mencken's wisecrack that 'the most common of all follies
> is to believe passionately in the palpably not true.' Quite so. I
> suppose it could turn out that one's interest in having friends, or
> in reading fictions, or in Wagner's operas, is really at heart
> prudential. But the claim affronts a robust, and I should think
> salubrious, intuition that there are lots and lots of things that we
> care about simply for themselves. Reductionism about this plurality
> of goals, when not Philistine or cheaply cynical, often sounds simply
> funny. Thus the joke about the lawyer who is offered sex by a
> beautiful girl. 'Well, I guess so,' he replies, 'but what's in it for
> me?' Does wanting to have a beautiful woman - or, for that matter, a
> good read - really require a further motive to explain it? Pinker
> duly supplies the explanation that you wouldn't have thought that you
> needed. 'Both sexes want a spouse who has developed normally and is
> free of infection . . . We haven't evolved stethoscopes or
> tongue-depressors, but an eye for beauty does some of the same things
> . . . Luxuriant hair is always pleasing, possibly because . . . long
> hair implies a long history of good health.'
--ravi