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A theory is said to be deterministic if,given some all the positions and velocities of its particles at only one moment in time,it completely determines what will happen before and after that moment. The laws of Newton are deterministic:once we completely specify the state of a system at a given moment,its evolution is absolutely determined. Newton’s equations leave no room for wiggling.
However,the fact that a theory is deterministic does not mean that it is actually possible to predict the evolution of a system in practice,since sensitivity to initial conditions prevents that in a majority of systems.