Originally Posted by lectricpharaoh

This is an interesting point, and echoes what I've believed for a long time.

To explain, let me give an example about randomness. Imagine you're rolling a six-sided die. What number comes up will depend on the variables involved, such as the position of the die as it left your hand, the height above the surface you're rolling it on, what kind of surface, the amount of 'spin' you imparted to the die, material and shape of the die, and so on. Even nigh-imperceptible factors, such as the Earth's spin, air currents, or position of the moon could affect things, as all exert some influence, however minuscule. In fact, in any system, there will be an infinite number of factors exerting influence, but only a small number of these will have a significant impact; as such, only these factors need to be considered in most cases.

Now, if one could roll an identical die in an identical way on two separate occasions, and every single factor was identical, then the result would be the same. Randomness is simply the label we've come up with when we cannot control the inputs to a great enough extent to have certainty of the outcome.

Now take a biological system. Every such system is extremely complex, and the factors that exert a measurable influence are far more numerous, making it even harder to make predictions. However, just because we cannot predict the outcome does not make it any less fixed. Since we cannot measure every factor (due to their number being infinite), we must settle for measuring only those we believe to weigh significantly in the outcome. In many systems, however, even this number is so great as to make the prediction come after the actual event. When I was a kid, I read a book 'When HARLIE Was One' about an AI; at one point, the AI was at risk of being terminated and sought to make itself useful by having a 'Graphic Omniscient Device' extension built. Here's an excerpt from the book after G.O.D. had been approved:
Yes, I'm rambling now. My point, though, is that if everything is fixed, there cannot be free will. However, there can be the appearance of it, since as far as we can tell, it's not fixed. To use another analogy, imagine you go see a movie. The ending is the same regardless of whether you've seen the movie before, but if you've not seen it before, you can still enjoy it. It has the appearance of being unpredictable to the audience, but that's all.