What is it like to be a bat? What is it like to perceive your surroundings using echolocation, to fly, and to hang upside down to sleep? As humans, we can imagine what it is like to do these things, but we can never truly know the conscious experience of life as a bat. Or any animal. Or, to a certain extent, other humans.

Here’s Why

The inherent subjectiveness of consciousness is at the heart of philosopher Thomas Nagel’s landmark 1974 article, “What Is It Like to Be a Bat?” The article tackles the mind-body problem, a debate over whether or not the mind—as in, thoughts and consciousness—is distinct from the physiological processes of the body. Nagel contends that all organisms, humans and animals alike, possess a “subjective character of experience” that cannot be explained by physical phenomena. He defines this as “something that it is like to be that organism – something that it is like for the organism.” In other words, the experience of life as a bat, with all of its faculties from wings to sonar perception, is fundamentally different from the experience of life as a human with all of its unique physical attributes.

Nagel’s “What Is It Like to Be a Bat?”

Thomas Nagel’s “What Is It Like to Be a Bat?” is one of the most prolific thought experiments of the modern era. It explores the nature of consciousness, for both humans and other animals, and the limits of human imagination. It also challenges the extent to which objectivity and reductionism are possible, highlighting the significance of subjectivity in conscious experience.

Thought Experiment

In his article, Nagel challenges the philosophical theory of reductionism, which asserts that all phenomena can be explained by simpler phenomena—essentially, that all things and events are brought about by smaller things and events in a cause-and-effect sequence. Reductionist theory holds that mental processes are the sum of chemical and physical reactions in the brain; therefore, consciousness is not subjective but a mere product of other events. According to Nagel, the subjective nature of experience, the idea that each person has thoughts and consciousnesses totally unique to them, undermines reductionist attempts to explain mental processes. Nagel argues that there is little physical evidence to show that a system of reactions in the brain produces consciousness, and if that were true, we would not feel subjectively different from others in our thoughts and experiences.

Nagel illustrates these ideas with the metaphor of “being” a bat, which, like all animals, is assumed to have consciousness. A human can imagine what it is like to be a bat by adopting its point of view. However, by virtue of being a human and not a bat, it is impossible to know “what it is like for a bat to be a bat.” The imagined scenario only reveals what it would be like for a human to project its consciousness into a bat’s body. Since a human is inherently not a bat, it cannot know the conscious experience of being a bat from birth.

So What?

Nagel’s influential thought experiment inspired years of speculation and research into human and animal consciousness, but it remains as confusing and inconclusive as ever. Perhaps the most important takeaway from the article is the consideration of subjective experience. As Nagel explained, it is possible to imagine someone else’s thoughts and experiences by assuming their point of view, but it is impossible to think those thoughts and live those experiences for oneself. The subjective character of experience for a congenitally blind or deaf person is not accessible to someone who was born with fully functional senses, and vice versa. So, before making judgments about a person’s character or behavior, it is important to remember that you have not lived their life. As much as you can imagine what it is like to be a bat or another person, you will never completely know what that experience is like for them.

    Learn More

    1. CrashCourse. (2016, Aug 1). Where Does Your Mind Reside?: Crash Course Philosophy #22.
    2. Ethics Explainer: What is it like to be a bat? (2019, April 15). THE ETHICS CENTRE.
    3. Nagel, T. (1974). What is it like to be a bat? The Philosophical Review, 83(4), 435.

    Think Further

    1. Do you agree with Nagel that consciousness cannot be explained by reductionism?
    2. Do you think that one day we might be able to know what it is like to be a bat rather than only imagine it?
    3. Which field of science do you think would most benefit from engaging with this thought experiment (psychology, zoology, neuroscience, etc.)?

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