When I signed up for this class I never realized how much I would be pondering such questions as what it means to be human. The more we read and discuss the issue, it seems the more complex it gets! However, so far I think Ghost in the Shell hit hard on trying to determine what it means to be human, although it seems this question is still almost impossible to answer or define. Kusanagi is mostly a mechanized being except her brain and spinal cord are human (so I found). However, on her scuba expedition with Batou, we learn what's on her mind. She defines herself through the nature of her experiences personal to her, how she gains knowledge through these experiences, and so forth. Also, the personal beliefs she has within her help Kusanagi to figure out what her experiences mean.
Later in the movie we see the encounter between Kusanagi and the Puppet Master. Upon looking at the cryptic image of the blond girl the Puppet master possesed, Kusanagi notes how they "look alike" and then questions whether or not her experiences are actually her own or human. She makes a really interesting point when stating that being treated like a human doesn't prove that she is human (there goes that definition:) At one point the Puppet master argues with Nakamura and the idea that memory defines mankind is brought up. Nakamura refutes the Puppet Master (or I guess Project 2501) is human but is shot down when 2501 tells him to prove his exsistence. What is most interesting is however is when Kusanagi's ghost interacts with Project 2501's ghost. We find out that 2501's believes two major components of life is reproduction and death, which he lacks. They also discuss the importance of variety and originallity in living beings. Already the movie has defined for us many different views on what it means to be human or have life.
Finally, I thought the concept of 2501 merging his ghost with Kusanagi's was an intriguing way in which cyborgs could reproduce to create a new entity, which as it seemed would be a pretty powerful creation. This is somewhat similar with Wintermute wanting to merge with Neuromancer. Wintermute, like 2501, are stuck without bodies and are just "ghosts" exsisting in the world. Also, both Neuromancer and Kusanagi have established personalities and both also worry that a merging would diminish or destroy their already created selves. Though Kusanagi agrees to merging with 2501, it seems that at the end of the movie the final entity is more Kusanagi than 2501 so maybe her fear of losing herself didn't happen to a full extent. It would be interesting to see the second movie or the series to see what kind of being Kusanagi truly is.