What Is It Like to Be a Bat?
"What Is It Like to Be a Bat?" is a paper by American philosopher Thomas Nagel, first published in The Philosophical Review in October 1974, and later in Nagel's Mortal Questions (1979). The paper presents several difficulties posed by consciousness, including the possible insolubility of the mind-body problem owing to "facts beyond the reach of human concepts", the limits of objectivity and reductionism, the "phenomenological features" of subjective experience, the limits of human imagination, and what it means to be a particular, conscious thing. Nagel famously asserts that "an organism has conscious mental states if and only if there is something that it is like to be that organism—something it is like for the organism." This assertion has achieved special status in consciousness studies as "the standard 'what it's like' locution." Daniel Dennett, while sharply disagreeing on some points, acknowledged Nagel's paper as "the most widely cited and influential thought experiment about consciousness.":441 Peter Hacker analyzes Nagel's statement as not only "malconstructed" but philosophically "misconceived" as a definition of consciousness, and he asserts that Nagel's paper "laid the groundwork for…forty years of fresh confusion about consciousness.":13
Nagel challenges the possibility of explaining "the most important and characteristic feature of conscious mental phenomena" by reductive materialism (the philosophical position that all statements about the mind and mental states can be translated, without any loss or change in meaning, into statements about the physical). For example, a reductive physicalist's solution to the mind–body problem holds that whatever "consciousness" is, it can be fully described via physical processes in the brain and body.
Nagel begins by assuming that "conscious experience is a widespread phenomenon" present in many animals (particularly mammals), even though it is "difficult to say [...] what provides evidence of it." Thus, Nagel sees consciousness not as something exclusively human, but as something shared by many, if not all, organisms. Nagel must be speaking of something other than sensory perception, since objective facts and widespread evidence show that organisms with sensory organs have biological processes of sensory perception. In fact, what all organisms share, according to Nagel, is what he calls the "subjective character of experience" defined as follows: "An organism has conscious mental states if and only if there is something that it is like to be that organism – something that it is like for the organism."
The paper argues that the subjective nature of consciousness undermines any attempt to explain consciousness via objective, reductionist means. The subjective character of experience cannot be explained by a system of functional or intentional states. Consciousness cannot be fully explained if the subjective character of experience is ignored, and the subjective character of experience cannot be explained by a reductionist; it is a mental phenomenon that cannot be reduced to materialism. Thus for consciousness to be explained from a reductionist stance, the idea of the subjective character of experience would have to be discarded, which is absurd. Neither can a physicalist view, because in such a world each phenomenal experience had by a conscious being would have to have a physical property attributed to it, which is impossible to prove due to the subjectivity of conscious experience. Nagel argues that each and every subjective experience is connected with a "single point of view", making it unfeasible to consider any conscious experience as "objective".
Nagel uses the metaphor of bats to clarify the distinction between subjective and objective concepts. Bats are mammals, so they are assumed to have conscious experience. Nagel used bats for his argument because of their highly evolved and active use of a biological sensory apparatus that is significantly different from that of many other organisms. Bats use echolocation to navigate and perceive objects. This method of perception is similar to the human sense of vision. Both sonar and vision are regarded as perceptional experiences. While it is possible to imagine what it would be like to fly, navigate by sonar, hang upside down and eat insects like a bat, that is not the same as a bat's perspective. Nagel claims that even if humans were able to metamorphose gradually into bats, their brains would not have been wired as a bat's from birth; therefore, they would only be able to experience the life and behaviors of a bat, rather than the mindset.
Such is the difference between subjective and objective points of view. According to Nagel, "our own mental activity is the only unquestionable fact of our experience", meaning that each individual only knows what it is like to be them (subjectivism). Objectivity requires an unbiased, non-subjective state of perception. For Nagel, the objective perspective is not feasible, because humans are limited to subjective experience.
Nagel concludes with the contention that it would be wrong to assume that physicalism is incorrect, since that position is also imperfectly understood. Physicalism claims that states and events are physical, but those physical states and events are only imperfectly characterized. Nevertheless, he holds that physicalism cannot be understood without characterizing objective and subjective experience. That is a necessary precondition for understanding the mind-body problem.
Dennett denies Nagel's claim that the bat's consciousness is inaccessible, contending that any "interesting or theoretically important" features of a bat's consciousness would be amenable to third-person observation.:442 For instance, it is clear that bats cannot detect objects more than a few meters away because echolocation has a limited range. He holds that any similar aspects of its experiences could be gleaned by further scientific experiments.:443 Kathleen Akins argued that much about bat subjectivity, such as the function of cortical activity profiles of the bat's brain, remains to be fleshed out in neuroscientific detail, and Nagel is too quick in ruling these out as answers to his central question.
- Nagel, Thomas (10 March 2005). Honderich, Ted (ed.). The Oxford Companion to Philosophy. Oxford: Oxford University Press. p. 637. ISBN 978-0-19-103747-4.
- Nagel, Thomas (1974). "What Is It Like to Be a Bat?". The Philosophical Review. 83 (4): 435–450. doi:10.2307/2183914. JSTOR 2183914.
- Levine, Joseph (2010). Review of Uriah Kriegel, Subjective Consciousness: A Self-Representational Theory. Notre Dame Philosophical Reviews 2010 (3).
- Dennett, Daniel C. (1991). Consciousness Explained. Boston: Little, Brown and Company.
- Hacker, P.M.S. (2002). "Is there anything it is like to be a bat?" (pdf). Philosophy. 77: 157–174. doi:10.1017/s0031819102000220.
- Hacker, P.M.S. (2012). "The Sad and Sorry History of Consciousness: being, among other things, a challenge to the "consciousness-studies community"" (pdf). Royal Institute of Philosophy. supplementary volume 70.
- Wimsatt, William C (1976). Reductionism, Levels of Organization, and the Mind-Body Problem. Springer US. pp. 205–267. ISBN 978-1-4684-2198-9.
- "Qualia | Internet Encyclopedia of Philosophy". www.iep.utm.edu. Retrieved 2015-06-01.
- De Preester, Helena (2007). "The deep bodily origins of the subjective perspective: Models and their problems". Consciousness and Cognition. 16 (3): 604–618. doi:10.1016/j.concog.2007.05.002.
- Bickle, John; Mandik, Peter; Landreth, Anthony. "The Philosophy of Neuroscience". Stanford Encyclopedia of Philosophy. Stanford. Retrieved 2 September 2020.
Kathleen Akins (1993a) delved deeper into existing knowledge of bat physiology and reports much that is pertinent to Nagel’s question. She argued that many of the questions about bat subjective experience that we still consider open hinge on questions that remain unanswered about neuroscientific details. One example of the latter is the function of various cortical activity profiles in the active bat.
- Akins, Kathleen (1993). "What is it Like to be Boring and Myopic". In Dahlbom, Bo (ed.). Dennett and His Critics: Demystifying Mind (PDF). Cambridge, MA: Basil Blackwell. p. 125-160. ISBN 0-631-18549-6.