One word: corroboration. You know reality from hallucination/dream because one survives objective verification, the other does not. Let me turn the question bac

One word: corroboration. You know reality from hallucination/dream because one survives objective verification, the other does not. Let me turn the question back on you: what use is there in NOT drawing this distinction? (ie. what use is denying that there is a knowable reality, and then our interpreted knowledge. territory/map)