Externality

Externality is an illusion created by a rationalising mind which misinterprets perceptive experience & creates the notion of external objective & solid reality separate from itself. Externality, in turn, helps to fix the illusion of the self as an independent reality existing in, but distinct from, the externality which itself has created. Or perhaps it would be more accurate to say, which itself has hallucinated.

Just struck me that externality was already a word.
Definition: An externality is an effect of a purchase or use decision by one set of parties on others who did not have a choice and whose interests were not taken into account.
I could probably work this into my piece...something along the lines of the philosophical creation of the external objectivity, less popularly known as the schizophrenic worldview, by some highly intelligent lunatics screwing up the direct experience of reality for everyone else. Reality as something to be categorised, dissected, made into lists, etc. In other words, the history of Western civilisation as the bastard offspring of metaphysical/philosophical accountants.