Jeffrey Kaplan doesn't just explain a famous philosophy paper; he dismantles the comforting assumption that science can eventually explain away our inner lives. In a world obsessed with data and reduction, Kaplan argues that there is a fundamental gap between knowing how a brain works and knowing what it feels like to be that brain. This isn't abstract academic navel-gazing; it is a direct challenge to the idea that consciousness is merely a biological machine waiting to be reverse-engineered.
The Reductive Trap
Kaplan begins by setting the stage with a clear definition of the enemy: physicalism. He describes this as the theory that "everything in the universe is physical" and that mental states are "nothing more than some physical stuff." The core of his commentary is that physicalism is inherently reductive. To illustrate this, he uses the example of lightning, noting that science has successfully reduced lightning to "nothing more than electric discharge."
He argues that physicalism attempts to do the same with the mind, reducing thoughts, beliefs, and sensory experiences to protons, neutrons, and electrons. "If Nagel's attack on physicalism succeeds, then all those versions of physicalism don't work," Kaplan writes, emphasizing that a defeat for the general theory means a defeat for every specific version, from behaviorism to functionalism. This framing is effective because it raises the stakes immediately; it's not just about one theory of mind, but about whether the scientific method can ever fully capture the human experience.
"A rock doesn't experience darkness. Close your eyes right now. There's a way it feels to see nothing, to experience darkness, right? But a rock has no experiences at all."
Kaplan uses this distinction to separate mere existence from consciousness. He points out that while a rock exists, there is "nothing that it is like" to be a rock. In contrast, even a hypothetical thirty-foot-tall human would have a subjective experience. This distinction is crucial because it isolates consciousness as a unique property that cannot be explained simply by the presence of matter. Critics might note that this relies heavily on intuition, which can be unreliable in philosophy, but Kaplan's clarity makes the intuition difficult to dismiss.
The Pink Ink and the Color Detector
To drive the point home, Kaplan introduces a thought experiment involving a simple color detector and a patch of pink ink. He argues that while a machine can identify the wavelength of light and label it "pink," it lacks the subjective experience of the color. "It feels a certain way visually to you to see this pink ink. It's that pinky way. It's pink," he writes. The machine, by contrast, "doesn't get the pink experience."
This section is the piece's most potent argument against reductionism. Kaplan suggests that there is an "extra thing" that conscious beings possess which machines lack, regardless of how complex the machine becomes. He extends this to physical sensations like hunger, noting that "it feels a certain way" to be hungry, distinct from the pain of a cut or a punch. "You're conscious of your hunger. You're aware of it. But more than just being aware of that hunger, it feels a certain way to you to be hungry."
This highlights the "hard problem" of consciousness: explaining why physical processes give rise to subjective feelings at all. Kaplan's use of everyday examples like hunger and color makes a dense philosophical concept accessible without dumbing it down. He effectively argues that subjective experience is a fact in itself, not just a byproduct of physical states.
The Bat's Perspective
The centerpiece of the commentary is the exploration of Thomas Nagel's famous 1974 paper, "What Is It Like to Be a Bat?" Kaplan explains that bats use echolocation, a sense humans do not possess. He asks the reader to imagine what it is like to navigate the world using sound waves bouncing off trees. "We have no idea what that feels like, what that conscious experience is like," Kaplan states firmly.
He debunks the common misconception that we can simply imagine ourselves flying or wearing fake wings to understand the bat. "You can imagine what it's like to be a human acting like a bat," he notes, but that is not the same as understanding the bat's own perspective. He even references the superhero Daredevil to illustrate how pop culture often fails to capture the true alien nature of such a sense. "That's not what it's like. That's just some stuff that some movie people made up."
"Whatever may be the status of facts about what it is like to be a human being or a bat or a Martian, these appear to be facts that embody a particular point of view."
This quote encapsulates Kaplan's main takeaway: consciousness is inextricably tied to a specific subjective perspective. Facts about consciousness are not objective data points that can be observed from the outside; they can only be known by inhabiting that specific point of view. This is a profound limitation for any physicalist theory that claims to explain everything from a third-person, objective standpoint. If the facts of consciousness are inherently subjective, then a purely objective science may never be able to fully explain them.
Bottom Line
Jeffrey Kaplan's commentary succeeds in making a complex philosophical argument feel urgent and personal, proving that the gap between physical processes and subjective experience remains the most stubborn problem in science. The strongest part of the argument is the insistence that subjective facts cannot be reduced to objective data, a point that challenges the very foundation of modern materialism. However, the argument's biggest vulnerability is its reliance on the limits of human imagination; just because we cannot currently imagine being a bat does not prove that we never will, or that the experience isn't reducible in principle. Readers should watch for how this "hard problem" influences future debates in artificial intelligence and neuroscience, as the definition of consciousness remains the ultimate barrier to understanding the mind.