Assume for the sake of argument that there are no ''things'', that instead everything is one. Does it follow from this that change is impossible and that any change we experience through the senses is an illusion? This is precisely Parmenides' argument in On Nature, which argues that change is impossible. By contrast, Heraclitus argues that change is reality. We seem to have two diametrically opposed views here. One claims that change is an illusion; the other claims that change is all that there is. However, despite this difference, both Parmenides and Heraclitus are monists; they both believe that all is one. For Parmenides, the one is ''Being'' (which Parmenides likens to a ''well-rounded sphere''), for Heraclitus it is one process. Note that both views seem compatible with modern science in their different ways: Parmenides' block universe is consistent with Einstein's four-dimensional space-time continuum; Heraclitus' becoming is consistent with the reduction of ''matter'' to energy.

It seems to me that Parmenides' monism is more consistent than Heraclitus' monism. More generally, it seems impossible to be a monist and to assert that there is change, since change presupposes the existence of things. If there is only One, then how can it change? - there is nothing other than itself to change into, and changing into itself is clearly not a change.

Monism entails Being; pluralism entails Becoming. Heraclitus is a monist who declares that all is one, therefore his position is self-defeating.

So, my question is: is monism incompatible with change?