In the pantheist’s attempt to reduce everything to one, he states that all distinctions are illusory. There is neither pain nor joy, neither truth nor error, neither freedom nor slavery – for all is one. Dualism, they contend, posits one reality against another – whether this takes the form of the age-old philosophical dualisms of Subjectivity vs. Objectivity, Ideality vs. Actuality, or Diachronicity vs. Synchronicity – and fails to see that such distinctions have no substance to them.
Problematically, however, this is itself a distinction that needs to remain firmly fixed in its place in order for monism to function. Monism is logically impossible, for if it is true, then it is an incurably dualistic doctrine, postulating (a.) the reality of the One in contradistinction to (b.)the illusion of the many. This is not monism; it is dualism of the most pronounced sort. It is, in a sense, nothing very different at all from the ancient Greek binary opposition: Ideality Vs. Actuality.
The monist, therefore, is not a monist, but an explicit dualist. And even if he attempts to avoid this inherent dualism of his by saying that the illusion of difference, multiplicity, plurality, etc is supervenient upon the reality of the One, he is still in a bind. For if the One can only be understood by means of the many, and the many is an illusion, then upon what basis does he assert that his doctrine of all being “One” is correct?