No, it doesn't follow. Compare: If an evil demon were thoroughly deceiving me right now about my surroundings, then my current perceptual experience would -- unbeknownst to me -- be unreliable. But the truth of that conditional doesn't imply that my current perceptual experience is -- unbeknownst to me -- unreliable. Likewise, if zombies are possible, and if they claim that they have conscious experience, then it follows that claiming to have conscious experience doesn't imply having conscious experience. But we knew that already.

I'm not sure I would use quite the verb "perceive" to describe our cognitive grasp of natural laws, but I don't see any reason why we can't discover at least some natural laws, including those that have shaped our ability to perceive (or discover). That is, I don't see any reason why a natural law's having shaped our ability to perceive should make that natural law especially hard for us to discover. It's not as if we should think of natural laws as having purposely shaped our ability to perceive in order to keep themselves hidden from us.

Thanks for your interesting question. I don't think there's anything fallacious about it. But I do think that, at bottom, it's an empirical question -- one that we can't expect to answer just by thinking hard about it. What you say in answer to it seems plausible to me: If all that I ever receive at my auditory organs is a totally undifferentiated sound, no matter what I do, then it's hard to see what function my auditory organs are performing for me or why I would even be aware that I had them. But I think that a confident answer to your question depends on properly gathered empirical data. You might look into the psychology literature to see if anyone has investigated this topic.

I agree. I don't know what Berkeley says about whether any nonhuman animals possess minds, but on his view, I take it, nonhuman animals would need to possess minds in order to perceive anything. Indeed, according to Berkeley, not only does the tree make no sound unless a mind perceives the sound, but the tree doesn't even exist without a mind to perceive it. (Even if no finite mind perceives the tree, Berkeley attributes the tree's existence to the tree's being perceived by God's mind.) Notice, too, that if we construe "a sound" dispositionally, i.e., as simply a disturbance that would be heard if there were a normally equipped listener to hear it, then sounds can occur even with no listeners (human or nonhuman) on the scene.

Two replies: 1. I'd caution against equating natural with non-human , let alone with non-living . Many living beings are in their natural state despite being alive, and many (if not all) human beings are in their natural state despite being human. A hermit crab in its borrowed shell is in its natural state, and so is a human being fully clothed inside his/her house. We human beings naturally clothe and shelter ourselves. 2. Your question seems a bit like the old chestnut 'If a tree falls in the forest, and nothing is around to hear it, does it make a sound?' If a given object reflects light in the visible spectrum, but nothing is around to detect that reflected light, is the object visible? Both questions turn on how we define terms, in particular 'sound' and 'visible'. If sound is simply vibrations that would be detected by a sound-sensor were one present, then surely the falling tree makes a sound. Likewise, if 'visible' means ' would be seen by a normal human observer looking...

I don't think that such an argument would rationally compel external-world skeptics (who say that no one can know that there's an external world) to abandon their view. External-world skeptics think that no one can know that solipsism is false, where solipsism is the claim that nothing external to oneself and one's mind exists. The solipsist won't grant that geometry consists of truths that are independent of his own mind, because he thinks nothing is. The solipsist could admit that his perceptions have a geometric character to them without having to attribute that character to something external. So I don't think solipsism can be disproven in the way you suggest. All of this assumes that solipsism is otherwise intelligible. But one might argue that solipsism is unintelligible because it relies on the incoherent idea of a 'private language', an idea explored in detail in this SEP article .