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). In it, Nagel argues that materialist theories of mind omit the essential component of consciousness, namely that there is something that it is (or feels) like to be a particular, conscious thing. He argued that an organism had 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." Daniel Dennett called Nagel's example "The most widely cited and influential thought experiment about consciousness.":441
The thesis attempts to refute reductionism (the philosophical position that a complex system is nothing more than the sum of its parts). For example, a physicalist reductionist's approach to the mind–body problem holds that the mental process humans experience as consciousness can be fully described via physical processes in the brain and body.
Nagel begins by arguing that the conscious experience is widespread, present in many animals (particularly mammals), and that for an organism to have a conscious experience it must be special, in the sense that its qualia or "subjective character of experience" are unique. Nagel stated, “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 to be itself.”
The paper argues that the subjective nature of consciousness undermines any attempt to explain consciousness via objective, reductionist means. A subjective character of experience cannot be explained by a system of functional or intentional states. Consciousness cannot be explained without the subjective character of experience, and the subjective character of experience cannot be explained by a reductionist being; 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 bugs 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
- 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.
- Dennett, Daniel C. (1991). Consciousness Explained. Boston: Little, Brown and Company.
- 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.