Thus the difference between analog and digital computation lies in a distinction between the continuous and the discrete, but it is not the precise mathematical distinction. What matters is the behavior of the system at the relevant level of analysis. The mathematical distinction between discrete and continuous is absolute, but irrelevant to most physical systems.
Many complex systems are discrete at some levels of analysis and continuous at others.
It doesn't matter what's going on below the level of relevant analysis. This is a significant empirical question, and the importance of connectionism is that it has tipped the scales in favor of the continuous. Having considered the differences between analog and digital computers, I'll now consider their similarities, which I think are greater than Harnad admits. First, both digital and analog computers provide state spaces , which can be used to represent aspects of the problem. Both digital and analog computers allow the programmer to control the trajectory of the computer's state through the state space.