One of the ideas that most hinders our attempts to get to grips with human behaviour is that which sees the individual agents and not the ecosystem; the consumer (nuff said on that one) and not the social world which individuals live and which they help create.
Much of cognitive psychology (and it's fair to say, much of the Nudge-gang's work) remains rooted in understanding the quirks of individuals' cognitive machinery; much of evolutionary psychology seems to be stuck in explaining the behaviour of individuals devoid of their real context - that is, other people. And in popular culture, we tend to go back to specifics (to excessive nodality as the network theorists would put it): to the specific individual and what causes or might shape that person's behaviour. This is as true of our political debates as it is of our personal lives.
But that's not what human life is like: it's not individuals, living in splendid isolation (except for those exceptional examples, such as the saints depicted above); for us social creatures, life IS other people (even if we find it hard to see it as such for our own lives).
Couple of things to think on:
Second, this fabulous book by Martin Nowak and Roger Highfield which I've been savouring which explores how high levels of co-operation emerge naturally in human populatons (and how Nowak has explored the subject).
Third, a thought from the priest who buried my late mother. "in the end all that matters - all that has ever mattered - is the people".
As a culture, we tend to be disdainful of this line of thinking. We tend to try to squeeze the individual agent back in but in doing so we rob ourselves of the really important insights into human behaviour.
"Most lives are a quotation from the lives of others" suggested Oscar Wilde. He meant it in a bad way but it turns out he's right about the fact, wrong about the significance of it.
Once you've understood this mechanic - the central point of our upcoming book - then please try to look beyond your "nodal" filter to the system which it creates.
Try to see the woods for the trees, if you like.