劍橋宣言的最後一段宣稱:「缺乏大腦新皮層似乎不表示生物沒有經歷情感狀態變化的能力。各類證據皆不約而同地指出:非人動物擁有構成意識所需的神經結構、神經化學及神經生理基礎物質,以及有能力展示帶有意圖的行為。因此,證據充份表明人類並非唯一擁有產生意識的神經基礎物質的生物。非人動物,包括所有哺乳類及鳥類、以及其他生物,包括章魚,也擁有這些神經基礎物質。」(“The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Nonhuman animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”) (The Cambridge Declaration on Consciousness, 2012, P.2)
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從生物學來看,我們的感覺以及感知是透過大腦的神經活動對應外界環境所產生表徵[1][2]。因此,美國哲學家、數學家與電腦科學家希拉里.普特南(Hilary Whitehall Putnam)就在《理性、真理和歷史》(Reason, Truth, and History)書中提出一個思想實驗,稱作缸中之腦(Brain in a vat),又或是桶中之腦(brain in a jar)。
橡膠手錯覺所帶來的身體轉移錯覺現象(body transfer illusion)說明了我們感受到的肉身其實只是大腦產生的一種假象,我們甚至能將自己的身體一部分移轉到虛擬的影像[9]上,讓自己出現類似靈魂出竅、遊離出身體的現象[10],又或是和別人身體交換的感覺[11]。這個現象也說明了在適當的實驗操作下,我們想要體驗莊周夢蝶是極有可能辦到的。
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