Earlier quoted context omitted.
just to add on with a slant toward the types of things HN is interested in, the point of "what is it like to be a bat" is essentially, you can't know what it's like to be a bat unless you are a bat (and I don't mean the paper should be read for that conclusion, you develop far more insight thinking your way through it) The old "how do I even know my red is your red" is a little piece of this puzzle. Perhaps someday t…
how do I even know my red is your red I get why kids ask this. I don't get why adults ask this. If you have normal color vision and don't have a tumor in your visual cortex your red is as close to my red as the red subpixels are on two units of the same television. Sure, you can't look at them and positively measure their identicalness, but they're being generated with the same hardware.
But to continue your analogy, after so many years of experiencing the world differently—different pasts, upbringings, worldviews—are they being interpreted by the same software? And that's the question that the paper really poses: are qualia real, and if so, is it ever possible to conclude that two individuals experience qualia in the same way?