The planet Pitch is covered in deep warm oceans. It is inhabited with intelligent starfish called Pitchians who wander about the dark depths of their home ocean, feeding on their world’s version of clams and oysters. Pitchians have no sense of sight and no sense of touch, just smell/taste and hearing with a form of echolocation. The Pitchian’s senses do not work at all like ours. If we could get into a Pitchian mind, we would hear nothing but sounds of different pitches and tones and volumes. There would be no sense of space like humans have. Larger objects produce louder echos, softer objects produce fuzzier echos, moving objects produce echoes with a shift and/or a doppler effect, but to the Pitchian, this is just a difference in quality of sound, it does not give a spatial intuition. It’s sort of like when a human hears two notes played on the same guitar at the same time. We do not sense two different sounds, but one sound with a special quality depending how the two notes harmonize.
Distance is similar. Close echos produce quicker echoes, which to the Pitchian is just a different quality of sound. The Pitchian does not perceive this as closeness/farness (because he has no sense of space), but he does sense that objects with a quicker echo (that is closer) are more directly important than objects with a slower echo. That is how he finds things on the ocean floor.
Furthermore, since the Pitchian has no sense of space, he has no sense of moving, and he also has no tactile sense at all. Rather, when he chooses to move, it seems to him nothing more than deliberately changing the sound qualities and the tastes that he is experiencing (of course he can only make changes in his senses consistent with his physical limitations, just like we can only move consistent with our physical limitations). A human watching the Pitchian would see the Pitchian moving, but to the Pitchian, he is only changing the quality of the sound associated with that clam. He changes the quality of the sound in the direction that we humans would call getting closer, but to the Pitchian, he is just controlling the sound to get the taste.
A Pitchian could potentially, with this array of senses and capabilities, come up with a physics. If we could communicate with the Pitchian, we could translate his notions of quality of sound into spatial concepts: bigger/smaller, closer/further, slower/faster, etc., but that is not at all what the terms mean to the Pitchian.
The human would translate the Pitchian physics into completely different concepts but both sets of concepts can be true at the same time. How? Well, let’s say we have a translation H(p) which translates a Pitchian concept p into a human concept H(p). If a Pitchian concept of a natural law says that p1, p2, …, pn leads to p, then this could be translated into a human-concept proposition that says H(p1), H(p2), …, H(pn) leads to H(p). If the translated proposition is true, then we can say that the Pitchian law and the human propositions are both true. If this translation is possible in both directions, and true statements map to true statements in both directions, we can say that the Pitchian woldview and our worldview are isomorphic, that is, they have the same abstract structure.
But notice that I referred to Pitchian law corresponding to a human proposition rather than to a human law. The reason is that even if our physics are isomorphic, what the Pitchians consider laws might not seem like laws to humans, but rather mere consequences of laws, because even within those isomorphic spaces what seems significant to Pitchians, what seems like the pivotal factor, is likely to be a lot different from what seems significant to humans.
Now what about metaphysics? The Pitchian Aristotle will try to explain their view of the world in terms of their concepts. He would say that there is some essence to certain categories of sounds that causes them to produce certain shift/Doppler qualities under certain conditions. When we translate this concept, we get H(sound) = object, H(shift/Doppler quality) = motion. What seems essential to the Pitchian Aristotle seems accidental to the human Aristotle.
By contrast, the Pitchian Kant will say that the Pitchian awareness of the world is mind-dependent. He will say that although there is something that is mind-independent, the Pitchian way of conceptualizing and intuiting the world is not the same thing as the way the world really is. He will call shift/Doppler sound quality a precondition of thought rather than a fundamental part of the underlying, mind-independent world.
The Pitchian Kant will be closer to the truth than the Pitchian Aristotle because when they enounter humans, the Pitchian Kantians will have no problem understanding that humans have a completely alien but isomorphic way of viewing the world, but the Pitchian Aristotelians will be forced to conclude that humans have a crippling inability to grasp the true nature of the world.
Also importantly, a lot of Pitchians will claim that by rejecting the noumenal reality of sound qualities, the Pitchian Kantians are rejecting the possibility of science, but they will be wrong. When they say that sound qualities are mind-dependent, they do not mean that those qualities are not real or that they are subject to the will like in a voluntary fantasy, because the qualities are imposed on the Pitchian by the underlying reality. All the Kantian is saying is that science cannot access the underlying reality because we can only think about the world in mind-dependent ways, and that while we can know the truth about the world, there are many isomorphic truths that would be completely alien to us.
Why does this matter besides being a more objective view of nature? Because it helps to explain how we can know things about the world–namely that since the world is mind-dependent, we can know thing about how our own mind observes things. This is an attempt to understand how science is possible.