 The argument from hallucination relies on the possibility of hallucinations as understood above. Such hallucinations are not like real drug-induced hallucinations or hallucinations suffered by those with certain mental disorders. They are rather supposed to be merely possible events. For example, suppose you are now having a veridical perception of a snow-covered churchyard. The assumption that hallucinations are possible means that you could have an experience which is subjectively indistinguishable—that is, indistinguishable by you, “from the inside”—from a veridical perception of a snow-covered churchyard, but where there is in fact no churchyard presented or there to be perceived. The claim that such hallucinations are possible is widely accepted but not indisputable (see Austin (1962) and Masrour (2020)). For more on hallucinations, see Macpherson and Platchias (2013).