I'm not trying to defend Leibniz' argument so much as point out the space in which he can make it. I think that you may be confusing the two in responding to me as, let's be clear, Leibniz is writing in an utterly distinct intellectual environment from us. The pragmatism of communication as a standard for assessing representations does not exist in the 17th century as human cognition is still being assessed in relation to a possibility of omniscience that sometimes goes by the name of God. Communication, or inter-subjective experience, only becomes a standard after Kant. So monads or Leibniz' way of talking about substances is a way to negotiate the unique problems of conscious perception in relation to that possibility of omniscience.
