plot, situation and world

In the post 'how to plot stories' I talked about how plot bleeds into the world that a story happens in. The more interesting and novel the world (as in scifi and historical fiction) the less central and compelling the plot moves have to be. Alfred Hitchcock when he was in conversation with Francois Truffaut made an interesting comment on his later films like 'The birds' compared to his earlier movies like 'the 39 steps'. He said that he felt that he wanted a 'situation' rather than a plot as a starting point. A 'situation' is a world on target for conflict. Milan Kundera (lots of names today) wrote that 'the terminal situation' is the current form modern stories take- meaning something similar I think. That is, because the reliable world has broken down, because the stable backdrop of, say, an Agatha Christie novel cannot be relied upon, we need in every story to do at least some world building to create depth and interest. This is the 'situation'.