Through the use of his famous “What is it like to be a bat?” analogy, Nagel argued that the reductionist based theories of mind are not capable of explaining the phenomenon of consciousness, and that the reductionist theories of mind also neglect to consider that consciousness is something more than neurological activity, but involves the “subjective character of experience”. Nagel argues that the subjective nature of consciousness cannot be explained through the use of objective analyses. By using the “what is it like to be a bat” analogy, Nagel claims that no matter how much a person might try to study bats in an attempt to understand what it is like for them to fly around at dusk with webbed wings, using echolocation to perceive the world in front of them, to hunt, and hang upside down, a person will never know what it is like. They will never be able to experience the world as the bat does (unless they were capable of transforming themselves into a bat), at best the person can only speculate and attempt to imagine what it is like to be a bat to the best of their abilities.
Nagel bases his argument on the idea that humans are incapable of knowing what it is like to be a bat, which is all well and good when we consider that this analogy looks at an animal that is incapable of communing its subjective conscious experiences with the outside world (it would be similar to asking what is it like to be a mouse, a robin, or even a flower), causing the relatability of this analogy within the topic of human consciousness to become questionable from the very beginning. The study of human consciousness is a bit different to what Nagel makes it out to be, in the sense that humans may commune with one another, through vocal and non-vocal methods (for example, people with Locked-in Syndrome are capable of conveying information, albeit limited information). Additionally, the analogy is grounded on the assumption that bats are capable of experiencing consciousness, as human understand it, beyond that of base desires of food, drink, shelter etc., if a human is able to conceive, and imagine, what it is like to feel hunger, thirst, tiredness, could the human then not be able to know what it is like for a bat to feel such things?
An objection to such a question might be posed as “how do we know that the bat does not feel anything beyond base desire?” The answer to which can be as simple as: we have not seen them exhibit anything beyond base desires. Bats have not shown higher order thoughts, nor have they exhibited love or the romance that accompanies such feelings. Nagel argues that humans will never know what it is like to perceive the world as bats do, but is that assumption entirely implausible? What if a person born blind was provided with the necessary appropriate apparatus to use sonar to detect obstacles, and grew up using the same method as bats do to navigate the world, would they not know what it is like for a bat to perceive the world through the use of echolocation? One would need not look any further than Daniel Kish, who perceives the world through the use of echolocation.
If we reconsider the question of “what is it like to be a bat?” as something that is closer to the topic of human consciousness it can somewhat change our perspective of the topic and the value of Nagel’s argument. If asked by someone “what is it like to be Mary?” I am certain I would be able to give a rather solid answer depending on how well I know Mary. I would know what it is like for her when she sees the world, hears noises, and tastes food. I would know how Mary experiences the world on a sensory level, to that degree I would know what it is like to be Mary. As to more personal experiences, for example the loss of a loved one, I might not know what it is like for Mary when she is told of the loss, but if I had experienced a similar loss (or an experience close enough to it) then I would be able to make a rather solid guess as to what it would be like for Mary in such a circumstance. Though this is not exactly the same as being in her shoes at the time and knowing the whirlwind of emotions that she might experience, I would be closer to knowing what it is like to be Mary than I would be anywhere closer to knowing what it is like to be a bat. Alongside this fact that I can relate to Mary because we are both humans and experience the world around us in a similar mannerism, Mary is also not limited in her communication skills (unlike Nagel’s bat), she is able to speak, write, and read in English at which point she will be able to tell me what it is like to be her. So, even if I was asked “what is it like to be Mary?” I might not be able to give a detailed and insightful answer as I would wish, I could simply ask Mary myself and allow her to tell me.