From my understanding, the "usual model" refers to the deceptive use of the words "is" and "are" in regards to how a mental and a physical term might refer to the same thing. The current concept of the word "is" does not make sense when saying that a mental term is a physical event. Bats sure seem like an alien form of life. Here is how their echolocation works: https://www.youtube.com/watch?v=qJOloliWvB8 A key part of Nagel's thought experiment is a rejection of philosophers' attempts to reduce consciousness to material explanations. The reductionist theory that many contemporary philosophers subscribe to believes that one kind of thing can be reduced to another kind of thing. In the mind-body problem, the reductionists believe that the mind and consciousness can be reduced to physical phenomena (like neurological signals). Thomas Nagel (born 1937) is an American philosopher and University Professor of Philosophy and Law Emeritus at NYU. His main areas of philosophical interest are political philosophy, philosophy of the mind, and ethics. Thomas was born in Yugoslavia (now Serbia), and arrived in the US in 1939. Nagel is a Fellow of the American Academy of Arts and Sciences.  Here is a lecture by Thomas Nagel about philosophy: https://www.youtube.com/watch?v=MwYZURDU6dA&t=749s For more about Thomas Nagel and his research: https://en.wikipedia.org/wiki/Thomas_Nagel What is it like to be a bat? First Published in 1974 in The Philosophical Review, Nagel’s argument about consciousness is still relevant today. Nagel writes that an essential part of consciousness is that there is something (a feeling), of what it is like to be a conscious thing, and that any organism has 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 to be itself.” This is one of the most cited philosophy articles ever written, and is a fundamental text in the philosophical literature. Here is a summary for the piece: https://en.wikipedia.org/wiki/What_Is_it_Like_to_Be_a_Bat%3F I see a barrier in trying to think that we could fabricate the experience of a bat without being able to be one, or any other creature. Simulating creature's behavior is straight enough, like mechanically in a virtual environment, but give a independent Self-expression computationally to a simulation of a complex system would not be enough to be a sucessfull simulation? The problem: What is Self-expression? Nagel is describing here that besides the biological limitations of human brains and bodies and our significant biological differences with bats, there is no objective way for us to consider the subjective experience of a bat or any other conscious being for that matter, because consciousness is a subjective phenomena with a single point of view and any objective perspective will come from a different point of view. What is the "usual model" that Nagel is referring to here? The core of Nagel's argument is that because experience is fundamentally subjective, trying to reach an objective view of experience is nonsensical, since a step towards objectivity is a step away from the subjective experience, since the latter inherently implies a point of view. The thing that confuses me here is that Nagel's (seemingly implicit) step that this implies subjective experience cannot exist in a physicalist picture. Nagel seems to say that subjective experience is tied to point of view, and points of view are accessible only to certain types, which are fundamentally subjective (Quoting page 442: "They are subjective, however, in the sense that even this objective ascription of experience is possible only for someone sufficiently similar to the object of ascription to be able to adopt his [sic] point of view---"). However, Nagel appears to take it as given that this means mental states/events cannot be physical states/events (see also page 447). What exactly is the argument for this? I do not see why the existence of subjective experience necessitates a "mental space" separate from the physical universe.