The first time I started wondering this was writing a pseudo-random number generator in a programming class. The concept that you could do such a thing is a bit of a trip. Generating randomness from an ordered program. Of course the trick is that you take a seed and put it through a very nonlinear mathematical transformation. Any small difference in a seed leads to huge differences in the result. If you know everything, the seed and the transformation, the result is easy to predict. If not it's impossible. The world around us is highly nonlinear and there are clear limits on how much we can know about the world around us. Everything that occurs on time scales we can grasp follows predictable laws. We only find what we believe to be randomness in quantum phenomena that occur so fast that there may be question of whether we catch all the details. So I ask you, do you think randomness is real?