Speaking of big concepts and important ideas in science fiction:
This is the scene in which the epistemological angst hits home for Major Kusanagi as her worry over still being human blossoms into anxiety over whether she was ever human to begin with. Beautifully executed through atmosphere and facial expression with no expository dialog whatsoever.
The second Ghost in the Shell film, Innocence also features a similar urban atmosphere scene at it's midpoint. Here, however, the focus is on Chinese immigration and integration of these people who are foreigners yet come from the same East Asian cultural civilization.
The marvelous thing about both of these films is how the intellectual themes underlie the plot, paralleling and giving to the support to character development without bogging down the narrative.
I prefer the first film, but that's purely due to my obsession with human thought and its ongoing evolution.