Comment by C-x_C-f

I think one can salvage the distinction between physical reality and subjective experience without positing an abstract ("Cartesian") dualism. It just so happens that most experiences can be categorized as being either external or internal, so we are led to believe that every experience fits into one and only one bucket. But I think that there are plenty of experiences that are not so easily categorized (e.g. feelings).

Demanding that there must be a perfect partition (i.e. assuming dualism) is an additional requirement, but it's not obvious that it should be a good requirement for a sound philosophical theory. In fact I believe it not to be sound, and I believe many philosophical hard problems come from bending over backwards trying to impose this condition.