It's no accident that Sarah Connor's famous dictum that there is "No fate but what we make" closely resembles Jean-Paul Sartre's first principle of existentialism, that "Man is nothing else but that which he makes of himself." As philosophy grad student Ro Smith explains in the above video (and accompanying essay), the Terminator films are full of existentialism.
A lot of Smith's essay "Existentialism and The Terminator" actually deals with the main lighting states in Cameron's two Terminator films (she doesn't deal with the other two movies or the TV series.) She connects the use of lighting in these films to the noir genre, in which lighting states are also "symbolically significant," and talks about the symbolism of the main types of lighting in these films.
But she also connects the films not just to questions of agency and free will, but also to the nature of objects. At one point, she writes:
In Sartre's 'Existentialism is a Humanism' he contrasts human beings, for whom existence precedes essence, with articles of manufacture, whose essence is determined by humans. A knife is a knife because humans design them for a purpose: to be used to cut things. Yet, equally, such articles lose their essence in the absence of humans to use them.
Terminator 2 brings the question of articles of manufacture vs self-determining minded beings to the fore. Skynet was a self-actualising AI, but always off screen. But in T2, Sarah removes the inhibition placed on the T-800 against learning. The T-800 is allowed to explore its own self-actualisation, and in doing so it comes to affect those around it; to build relationships. The T-800 may not have the ability to self-terminate, but he's capable of bringing the matter to the attention of Sarah Connor – that her brief fantasy of having a father figure for John cannot be allowed without consequences for the world. That is a moral action, and action that affects others, and that recommends a moral stance to others.
The whole thing is just masterful, and a breath of fresh air in film criticism. Thanks to whoever recommended this to me last week! [Rhube]