What is it like to be a bat?

>"An organism has conscious mental states if and only if there is something that it is like to be that organism – something that it is like for the organism."

IMHO the phrasing here is essential to the argument and this phrasing contains a fundamental error. In valid usage we only say that two things are like one another when they are also separate things. The usage here (which is cleverly hidden in some tortured language) implies that there is a "thing" that is "like" "being the organism", yet is distinct from "being the organism". This is false - there is only "being the organism", there is no second "thing that is like being the organism" not even for the organism itself.

I believe you're falling into a purely linguistic trap. In other languages we wouldn't even use the word "like" in this kind of constructions, that's an English thing because other wordings sound awkward, but I don't think it entails comparison.

In translations to Spanish, the article is titled "¿Qué se siente ser un murciélago?", literal word by word translation "What is felt being a bat?"

In French, "Quel effet cela fait-il d'être une chauve-souris?", literal word by word translation "What effect it makes to be a bat?"

In Chinese, "成为一只蝙蝠可能是什么样子", i.e., "To become a bat could be what feeling/sensation?"

None of these translations has a comparative word. And at least in Spanish (I won't speak about the other two because I'm not so proficient in them), using a comparative expression similar to "being like" in English ("¿A qué se parece ser un murciélago?") would sound awkward and not really convey the point. Which is why the translators didn't do so.

Of course I know that the original article is in English, but I think the author basically meant "What is felt being a bat?" and just used the "like" construction because it's what you say in English for that to sound good and clear. Your highlighted text could be rendered as "An organism has conscious mental states if and only if there is something that is felt being that organism – something that is felt by the organism." and it would be more precise, just doesn't sound elegant in English.

Wholeheartedly agree. I want to credit the GP one way, which is that the category they're identifying is real, namely of frivolous or circular comparisons. This just isn't one of those. It's a turn of phrase that's emphatic about the felt quality of qualitative experience. And in I think it's quite a good one, because in English it has just the right amount of cross-sections of connotation that it brings out this being felt quality that everyone reading it seems to understand. The idea has been around but this expression of it has gained the most traction in English.

As for whether I agree with Nagle, I find him consistently just wrong enough to be irritating in ways that I want to work out my thoughts in response to, which by some standards can be counted as a compliment. As much as I understand the turn of phrase and its ability to get people to grasp the idea, and I at least respect it for that reason, I kind of sort of always have the impression that this is what everyone meant the entire time and wouldn't have thought a whole essay emphasizing the point was necessary.