This is all a "what if the force was real?" thing. Except this topic is about what it is, not if it is real or not.
IS the force light and dark?
Or is the force just the force?
Or maybe it is an actual entity that is the Universe itself?
What could the force be?
Personally I see many people referring to the light side and dark side of the force. I think that this is a false statement, to assume that the force is light and dark side. I know that even Kyle Katarn was saying that the force is neither good nor evil, but rather it is just the force. It is the actions of the person using it that makes it good or evil. Let's say I use force heal on a wounded soldier. This could be considered a "light" power, but really it is the act that is light, for I could also be healing him, only to try to almost kill him again, then heal him (as a form of torture). Or force lightning. I could be attacking a group of soldiers with force lightning, which could be considered "dark". But what if these soldiers were trying to rape an innocent child? I would be doing an act of light because it would be protection. I still don't see why people say the light and the dark side of the force, or why it is inherently either one?
I think the reason there is continual reference to light and dark sides of the Force is because of the originial trilogy. Yoda talks about the light and dark sides, and the movies are canon for the whole Star Wars genre. I happen to agree that the Force is one, and that an individuals motivations and actions are what is light and dark, but Lucas wrote about the duality, and we're stuck with it.
The movie is a little too black and white for me. EU clears a lot of the confusion up.
The way Etah sees it; there is only one force. But itís not actions or even intentions that influence the force. IE The Jedi arenít the good guys and the Sith arenít the bad guys. The force is altered by how it is UTILIZED.
The reason the Sith focused on hate, anger, etc. isnít because they were evil its because the Sith AMPLIFY the force using passion. That is why the Jedi arenít supposed to marry. Love is as apart of the Sith way as hate, any true and deep feeling. You can think of the way the Sith use the force as the winds stoking the flames of a raging inferno.
The Jedi on the other hand emotionlessly FOCUS the force. You can think of the way the Jedi use the force as a laser, extremely focused, precision and piercing.
The Force is what you make of it. It is neither good nor evil, light nor dark, and has no real intentions. The people who can use it, or be used by it, as some Jedi prefer to say, are the ones who make it light or dark, depending on their actions. Even actions that, according to the old trilogy that are "dark", can be used for good, like Force lightning (as referenced above) for protection, just as long as the situation really calls for that sort of protection. And techniques like the memory rub (Jacen uses it on Ben Skywalker to block the boy's memory of his visit to Tenal Ka), which is technically a light skill Jacen learned from the Fallaanassi (sp?), can be used for ill purposes, to block the memory of a surprise attack or critical information, things like that. It's the Jedi and the Sith that ultimately cause the Force to seem, at first glance, split into two sides of light and dark.