Philosophy, first and foremost, is a pursuit of knowledge. But knowledge is just as much an attempt at grounding what a thing is not as much as it is knowing what it is. What is a rock? As a metaphysical skeptic my answer is “one can never definitively know” but it seems far more discussion is made by discussing what it isn’t. How is a blue rock different from a red rock? How is a rock different from a man? How is a man different from a god? Despite how vast the phenomenal differences in shape, size, texture and activity are they are only differences in phenomenal description. That is, there is no difference in metaphysics nor in normative claims that we know of. Obviously a Cartesian Dualist or a Utilitarian would disagree, but the entire point of metaphysical and ethical skepticism is we can’t know whether these philosophies are true or not.
Here we came across all three fundamental bifurcations, two were mentioned explicitly. Namely the difference between phenomenal knowledge (the world of appearances) and the reality of metaphysics (the noumenon) and the difference between descriptive and normative claims. Despite all the differences one can list of a rock and a man fundamentally all knowledge is limited in being only a descriptive account of sense perceptions – as all knowledge in the fields of science are. We know nothing of “reality” independent of our perception of it, therefore, to presume what we commonly perceive is mind-independent simply because it appears regularly is faulty. Berkeley, Schopenhauer, and other Idealists however commit the same error backwards, in positing that because I need to have eyes of a can for visual knowledge of the can to exist I have to see it for it to exist. Its true knowledge is mind-dependent, but knowledge-of-a-thing and the-thing-itself are two radically different things.
Just as we never directly perceive something that we know definitively is reality, despite how convincing it is to us, so we never have definitive knowledge of ethics despite the passions of human moral sentiment telling us ardently that such-and-such is either common sense or insanity. Human anthropology studies culture, and biology, psychology and other fields study pleasure and pain, attraction and aversion, but nothing in these fields is there one shred of data telling us that what is believed to be right is or what is pleasant is ethical. All we gain are descriptive accounts of human sentiment or biology, not what ought to be.
Moral Relativism from this makes the erroneous claim that no ethical claim is definitively true and Moral Nihilism claims that all ethical claims are definitely false. Like Utilitarianism, Divine Command Theory, Virtue Ethics and Kantianism, these systems make claims that cannot be grounded in reason and assume what cannot be made certain. Simply failing to prove my culture’s ethics’ correct does not prove them wrong – it simply means I have not proven them right. Ethical Skepticism, however, only claims that we cannot know what is right or wrong because Utilitarianism has been neither proven or disproven. Nor has Moral Nihilism or Kantianism.
All that can be described is knowledge of the moral passions, which is why when we study humanity, we can gain a sense of what it means to be moral but not what it means to know what to do and why. As the distinction between ‘ought’ and ‘is’ is made in Hume, the distinction between phenomena and numenon is made in Kant, so this distinction is made in Schopenhauer’s “The Basis of Morality.” Morality, being grounded in compassion, lies in the realm of phenomena and is a feeling, like love or anger, and is devoid of certain metaphysical or ethical substance.
We have not explicitly mentioned our third bifurcation however. It was implicitly raised when we asked “what is the difference between a rock and a man?” Some might think of the descriptive difference of appearance we mentioned, but most I believe would immediately think of the mental and phenomenological differences of the two. As far as we know, nearly all living human beings have a “mental life” and we have no evidence that any rocks do. This of course does not confirm that they don’t just that we have no empirical grounds to believe they do. But what are the empirical grounds for consciousness? How do I even know anything outside of myself is conscious? Being able to discern what is a “thing” and what is an “agent” with its own agency? Is it entirely a façade and bluster of confident false-knowledge to say that something has a “mental life” just because it appears to and certainly doesn’t if it doesn’t act as we think of a conscious thing? It appears so.
It must be so, for fiction has taught us that there are things which act as if they are “mentally alive” and yet are not, and there are things that which appears not conscious could be contain a subjectivity just as alert and vivid as you or I. Namely the stories of West World and Toy Story, both strangely enough having cow boys in them. In West World, there are automotons that are programmed to act as if they had a subjectivity of desires, hopes, pleasure, pain and so on and yet they don’t. If I replaced the automaton with a machine which did have a consciousness, all other things being exactly the same it would be impossible to tell the difference. You cannot tell me that they have subjective states because they wipe their minds daily to spare them the pain of their memories, for I can retort, “because they are designed to simulate human consciousness their memories are wiped to save them from simulating the pain or confusion of their past which would prevent them from being entertaining.” There is nothing in the world you can point to that there cannot be a convincing simulation of, including consciousness, which we never directly experience, save our own.
You cannot even tell me, “the unconscious automaton could not learn,” because just as a computer which is not conscious can learn the chess strategy of its opponent, and change its behavior accordingly, so a sophisticated computer seated in the skull of a robot cowboy can learn and act accordingly to knowledge being presented to it. Just as a masterful appearance of sorrow or anger as expressed by humans is only thus. It either does or does not relate to a subjective state – we can never know. This is seen in the sadist character in West World killing a man’s wife, and as the man weeps he says “you’re the most real when you’re suffering.” It could be that these machines have differing states of awareness and subjectivity similar to our own, or it could be that this machine has no consciousness and the facial expression of a person in pain simply creates the feeling of “realness” or “mental awakeness” for people, similar to Agent Smith arguing that humanity continually awoke from an always happy simulation. Both say more about human nature then about the nature of consciousness or reality.
Someone could argue that once we have knowledge of what appears to create pain and pleasure in subjective agents we can judge if a being is conscious by if they possess the same brains. This is valid if we assume what we cannot, which is that there is a direct correlation between dopamine in the brain and a subjective state of happiness, rather than actions or physiological states we associate with happiness through learned correlation. This is not knowledge however, it and it something assumed only because it has worked. Much like much of our thinking is heuristics which are not logically valid but statistically successful.
What can we know about the nature of consciousness? Only what it is not. Namely a physical thing. Even if the Materialists are correct and it is entirely generated by physical phenomena, and said phenomena is reality, there is still a necessary distinction between the brain and the mind. Subjectivity may exist in degrees which objective existence cannot. A thing can be large or small but regardless of a thing’s size they both exist in the same way. But the consciousness of a man and a chimpanzee could be said to be qualitatively different. This is something examined in Peter Godfrey Smith’s book: Other Minds.
I mentioned Hume, Kant and Schopenhauer in two fundamental distinctions and one distinction between human conceptions. We could easily mention Descartes in distinguishing between the Body and the Mind but we have to ask if we are doing the same thing as he. Descartes wanted to say they are necessarily two different metaphysical substances and attempted to (poorly) explain how these two distinct things affect the other. Instead, we are saying that they are merely two distinctly different concepts and to describe one is not to describe the other. Just as all the other distinctions made here were not distinctions in substance or reality but “what a concept expresses.” What is the thing-in-itself and what is things-as-they-appear? One of the inevitable results of skepticism is that they could in fact be the same thing, but they will never be the same conceptually. This world could, in theory, be exactly as it should be. Therefore, to describe it descriptively would be to describe normative existence. But this does nothing to the claim that to describe what a thing “is” and what it “ought” to be are two radically different conceptions of theoretically the same thing. Spinoza could be correct and everything is one substance, and even panpsychism be correct and everything has some subjective attributes to it. The fact remains that to describe its objective and subjective characteristics are definitively difference, regardless of what causes the other or how they manifest physically or metaphysically.
To summarize, the three fundamental bifurcations of existence are between the phenomenal and the noumenal, the descriptive and the normative and between objectivity and subjectivity. Skepticism claims we cannot have certain knowledge of whether in reality any of these three share something with their counter-part. What is known however simply from properly understanding the nature of the concepts is each is distinct from the other in their conception. Just as shapes and colors are two distinct things despite the fact we see red triangles.
Because we never directly experience the thing-in-itself, normative truth or subjectivity outside of our own minds a Skeptic would say we know nothing of these three outside of what we can gather from the concepts themselves. However, we do experience a world, so we can gain knowledge of any political convention, as it happens every election cycle. We see people who say they support X, Y, or non-X. What we don’t know is the metaphysical status of this convention, or whether it inhabits mind-independent reality. We cannot know whether what these people say they are in favor of or oppose is ethically right or wrong, all we can see is if their statements are logically consistent. We also cannot know whether these people actually believe what they say, because we cannot know of their intentions (which means we cannot know if their statements are moral apart from not knowing if they are ethical) and we cannot know if they actually have minds to possess the quality of intentionality, all we can know is that we read a report claiming they say they believe in X, Y or oppose X. The legitimacy of reports is another matter entirely and should be judged based on the integrity and legitimacy of the author and organization. This highlights the difference between Skepticism and distrust.
The three previous forms of Skepticism I have explained above describe philosophies which say that we illogically conclude that what we perceive is what it isn’t. We see something and falsely believe it is evidence of reality, ethics or a mind when we never perceive any of these things. But to see a history book and say “I don’t know if Australia exists because I haven’t seen it.” is not an equivalent claim because it is not Metaphysical Skepticism but Empirical Skepticism that wrongly holds that all empirical knowledge must be certain for it to be knowledge at all. I don’t after all, have perfect recall of my memories, so if this “Empirical Skepticism” was to disprove the possibility of knowledge the way the other three are to, then I literally could not know through experience anything outside of what I am experiencing this very moment.
It is true I do not know with certainty if Australia exists, both metaphysically and physically, but despite my inability to gain any access to its metaphysical status I can see which is more likely in terms of its being in this world as I understand it and live in it. Is there a conspiracy and people have claimed to be born in, grow up in, leave and come to Australia to fool me and potentially millions? Or is there a continent and country that exists just as much as Wisconsin or Canada does? Here we have to remember that Hume posits we should believe what seems more likely, but not that this is an absolute truth. For if the findings of our scientists our correct, one day the Sun will expand, though every day of our lives we were right to say, “it won’t happen today.” The world we live in is a world of correlations and associations; through these things we make judgements of probability. This, once again, is different then the main claim of Skepticism, which is that claims of knowledge have been made based on appearances which have no direct relation or ability to prove what we naively assume.