Robots, hearts, symbolism, and connections

So I just got back from seeing Terminator Salvation. I thought it was pretty good, although I've never seen any of the other Terminators, so. One thing I wasn't sure about, though, was the overarching message of the whole thing, the "what matters in being human is heart". How you can't put what makes someone human into a chip, or program it, or anything. What I thought of during the movie was actually the Tin Man (or Boq, in Wicked-verse, I suppose) from The Wizard of Oz. His whole deal was that even though he didn't have a physical heart, he was still the most kind and caring out of their whole group. So where does that leave all this heart-symbolism in books and movies?

Another thing that I just thought of was Data, from Next Generation. (Yes, I watch Star Trek. No need to make fun of me.) He's an android, he's completely programmed, a "machine"... but he's just as human as any other character on the show. I think there's an argument made at some point that more or less says that we (as in humans) are machines too, just of a different sort. And there is a whole episode called The Measure of a Man about how he has all the same rights as a person does. He doesn't have a heart, he could be one of these evil robots that are out to destroy humanity because he is an android... but he isn't. He's Data. He's awesome.

All of this stuff, it's about just what makes a person a person. What are the defining characteristics that makes us who we are? I guess it's kind of a big issue, not just in fiction but in real life; aren't so many controversial issues at least partially derived from this one? Abortion. When does a person become a person? Or something like... when it is morally okay to kill someone. What's so different about killing an animal and a person? Where is that dividing line that says "ok, now it is NOT ok to kill or enslave this being. They are a person."?

That's one of the major issues in The Measure of a Man, actually. Data is going to be pronounced "property of Starfleet", which would be deemed wrong if he were a sentient, living being - it would be slavery. So why, exactly, is he a person? He's an android, isn't he?

It's difficult. That's why I wasn't sure about the overarching message of Terminator Salvation. Basically because just because you don't have a heart, doesn't rid you of all humanity and feeling. Even though Data doesn't have emotions... he still "feels". His definition of friendship; "As I experience certain sensory input patterns my mental pathways become accustomed to them. The inputs eventually are anticipated and even missed when absent." It's different, but the same.

So what does make us human? I'm not sure. It's just something I was thinking about.