What’s it like to be you? Is it your thoughts and feelings, your physical body, or both? Something else entirely? In “What Is It Like to Be a Bat?”, philosopher Thomas Nagel argues that there is something special that captures any organism’s subjective quality: what makes an experience to be “like” that of a specific organism such as yourself, another human, or even a nonhuman animal. This suggests that there must be a way to know what it means to “be” that organism. But how much can you, a human, experience what it’s like to be an organism from another species?
Nagel uses the example of bats, as the species isn’t simple like a bacteria or a plant, but uses echolocation, hangs upside down, has webbed wings etc., which is very different from how humans behave. Even if you were to do all those things, you would be capable of understanding some, but not all, of the experience of a bat. Some humans, such as those who are blind, may have an easier time imagining what it’s like to be a bat, but not fully. Each living organism has their own unique perspective, and unless you were to physically transform into a bat, you still wouldn’t have a complete understanding. Even if you did, you wouldn’t be able to imagine what it’s like to be a bat in your human form. Likewise, it would be impossible for bats to fully imagine what it’s like to be you. You, and I, and every other organism, will never fully understand the perspective of someone else, much less that of an entirely different species. This must imply that there are certain concepts beyond human understanding, like how there are concepts that bats are incapable of understanding. For humans, at least, it’s possible to recognize that those concepts exist, even if we can’t understand them.
However, Nagel points out, there are some parts of our experiences that are objective. For example, two humans may have such similar experiences that one human describing their subjective experience to another can become objective. The less similar the two beings are, such as a bat and a human, the more difficult it is to adapt the point of view of the other. Take the example of eating a chocolate chip cookie; you’ve probably had one before and know someone, maybe a friend, who’s also eaten one. If you bite into the cookie and describe the taste, smell, texture, etc., to your friend, Nagel would call your description of the cookie objective because your friend is familiar with the subjective experience of eating a cookie. But it would be very difficult for a bat to understand what a cookie might taste like. Even if it has eaten a cookie before, the bat has different taste buds and can only take smaller bites. It’s difficult to imagine how an experience, which comes from the point of view of the being that is experiencing, can be separated and viewed objectively. Nagel says that the solution to the difference in experience between humans and bats, or any other two species, is to describe experience in terms of properties that are not human-specific, such as the taste of the cookie on your tongue. That would mean all species, from bats to humans, can understand physical events in objective terms.
No one has thought of a way to explain subjective experience in purely objective or physical terms, but doesn’t mean that we must be wrong about the nature of our mental or subjective experiences. Mental states, like the pleasure you get from eating a cookie, are also states of the body, like the molecules in the cookie activating certain taste bud receptors. We do not know how the pleasure connects to the activation of the taste buds, which means the relationship cannot be true. Nonetheless, it’s possible to understand that the two are connected without knowing why; not understanding the relationship between mental and physical states doesn’t mean it must be false.
Nagel then asks if there is any point in attempting to understand an experience “how it really is,” and not simply from his own point of view. What you subjectively experience when eating a cookie may be very similar to how it is to objectively eat a cookie, but that won’t help a bat understand what it’s like to eat a cookie. He proposes that we figure out how to describe, at least in part, subjective experience in a way that bats and other species can understand, even if those species are incapable of describing it themselves. This may even give organisms who can’t experience it firsthand a perspective different from the ones who did.
What, then, is it like to be you? Is it the subjective experience of being a human? Is it the subjective experience of not being a bat? Is it the ability to subjectively experience what it’s like to eat a cookie? It’s a difficult, if not impossible question to answer. Nagel doesn’t attempt to answer that question. Instead, he asks how to separate the “you” from everything else.