Consequently, it is natural to consider the voter's influence in probabilistic terms, i.e., as the probability of his causing a different alternative to be adopted as the result of his vote. The higher the probability between 0 and 1, the more likely is the event to happen. Given all the physical information about the roulette table, the throwing mechanism and the environment, it would in principle be possible to calculate exactly in which slot the ball will stop. In this perspective, we use probabilities only because, in practice, we cannot measure everything. We study some events as if they were random.
Probability theory is only a methodological trick to deal with our ignorance.
This approach has been undermined by Heisenberg's Uncertainty Principle, which puts some unreducible randomness in the very heart of matter. More recently, it has also been contradicted, in a different way, by chaos theory, which reconciles determinism and unpredictability. Moreover, man's free will introduces non-determinism into the world. Chance may very well be an inescapable feature of the universe. A carpenter working on the roof accidentally drops his hammer on the sidewalk.