My Skepticism

With the (important) proviso that "knowledge", "trustworthy", and "are true" need to be qualified with something like "approximately, kinda-sorta, most of the time", I think these premises should be assumed as working hypotheses on the grounds that if they are badly wrong then we're completely screwed anyway, we have no hope of engaging in any sort of rational thought, and all bets are off.

Having adopted those working hypotheses, we look at the available evidence and it seems like it fits them pretty well (note: this isn't a trivial consequence of having taken those things as working hypotheses; e.g., if we'd assumed that our perception, reasoning and memory are perfectly accurate then we'd have arrived quickly at a contradiction). Those propositions now play two roles in our thinking: as underlying working assumptions that are mostly assumed implicitly, and as conclusions based on thinking about things as clearly as we know how.

There's some circularity here, but how could there not be? One can always keep asking "why?", like a small child, and sooner or later one must either refuse to answer or repeat oneself.

Somewhat-relevant old LW post: The lens that sees its flaws. My memory was of it being more relevant than it appears on rereading; I wonder whether there's another post from the "Sequences" that I was thinking of instead.

With such skepticism, how are you even able to write anything, or understand the replies? Or do anything at all?

I think you misspelled "skepticism" in the title.

Also, your argument (including what you have said in the comments) is something like this:

Every argument is based on premises. There may be additional arguments for the premises, but those are arguments will themselves have premises. Therefore either 1) you have an infinite regress of premises; or 2) you have premises that you do not have arguments for; or 3) your arguments are circular.

Assuming (as you seem to) that we do not have an infinite regress of premises, that means either that some premises do not have arguments for them, or that the arguments are circular. Either way, you say, that means we have unjustified beliefs which are not known to be true.

This may be true, given a particular arbitrary definition of knowledge that there is no reason for anyone to accept. But if knowledge is defined in such a way as to be a contradiction, who would want it anyway? It would be like wanting a round square.

Memories can be collapsed under percepts.

In answer to your broader question - yup: you've hit upon epistemic nihilism, and there is no real way around it. Reason is Dead, and we have killed it. Despair.

...Or, just shrug and decide that you are probably right but you can't prove it. There's plenty of academic philosophy addressing this (See: Problem of Criterion) and Lesswrong covers it fairly extensively as well.

http://lesswrong.com/lw/t9/no_license_to_be_human/ and related posts.

http://lesswrong.com/lw/iza/no_universally_compelling_arguments_in_math_or/

Rather than going on a reading binge I recommend to just continue mulling it over until it clicks into place, because, similar to the whole "dissolve free will" thing, it feels clear in hindsight yet it is not easy to explain or understand explanations others provide.

I'll give it a shot anyway: The essential point is that ultimately you are a brain and you gonna do things the way your brain is designed to do them. Assuming you've satisfactorily resolved the whole moral nihilism thing (even though there is no divine justification for morality, we can still talk about what is moral and what isn't because morality is inside us), resolving epistemic nihilism follows an analogous chain of thought: There is not and cannot be any justification for human methods of inference[morality], but it still is our method of inference[morality] and we're gonna use it regardless.

gjm has mentioned most of what I think is relevant to the discussion. However, see also the discussion on Boltzmann brains.

Obviously, if you say you are absolutely certain that everything we think is either false or unknown, including your own certainty of this, no one will ever be able to "prove" anything to you, since you just said you would not admit any premise that might be used in such a proof.

But in the first place, such a certainty is not useful for living, and you do not use it, but rather assume that many things are true, and in the second place, this is not really relevant to Less Wrong, since someone with this certainty already supposes that he knows that he can never be less wrong, and therefore will not try.

Assume they're approximately true because if you don't you won't be able to function. If you notice flaws, by all means fix them, but you're not going to be able to prove modus ponens without using modus ponens.

I would agree if you can't trust your reasoning then you are in a bad spot. Even Descartes 'Cogito ergo sum' doesn't get you anywhere if you think the 'therefore' is using reasoning. Even that small assumption won't get you too far but I would start with him.

Standard methods of inferring knowledge about the world are based off premises that I don’t know the justifications for.

How do you come to that conclusion?

What the Tortoise Said to Achilles.

Any introduction or reader on contemporary epistemology that you'd find on amazon would address these three points.

You can think of what the points mean in the technical sense and try not to read anything more into them.

1) You sense something, your brain state is conditional on atleast some part of the universe. Do not make assumtions on whether it's a "fair" or "true" representation. At the most extreme you could have a single bit of information and for example no insight on how that bit is generated (ie by default and from epistemoligcal first grounds our behaviour is opaque).

2) We move from one computation state to another based on non-vanishingly on what state we were previously on. Ie our thoughts go in trains, it does matter what we thought before on what we will think next. Do not make any assumtion s that these trains have any "fair" or "true" representation about anything. We simply work in a not the way. We don't know how sane we are but we know that there is a method to our functioning, it is not adequately modeled as dice throws.

3) Our current computational state is the result of our past computations. Again no guarantees of "representing" or being "faitfull" to the past states are given.

Now your reservation about 1) does a photoreceptor need any other basis to fire rather than triggering? Is it possible for it to fire in "error"? For what we see is preciously how it fires. Then compared to a tactile sensor does a photoreceptor or it behave more "right" than other? From the inside we might not be able to distinguish which is which. So from the inside it seems taht mystery sense X fires sometimes and mystery sense Y fires sometimes. What would it even mean for these senses to be "misleading" or "false"?

The gripes about 2 can be framed as if you are able to grasp a situation one way then you can work on that. If you have no grasp of anything that would be equivalent like being like a dice. There need not be an all encompassing competency. Even if you have a basic abiity to imagine alternatives and then pick one you can work forward. What woudl be bad would be the inability to try a solution or being unable to be mentally stimulated by ones experience. Even if you begin with a flavour of madness you can come to know that flavour of madness and take into account it continuing forward. Ie you could have that when you think you see green you actually see red. If you then install a color reversal you can be more compatible/succesull with your surroundings/qualia-jungle. There is no "innate color ability" but being able to contextualise your thoughts with other experiences gives them a certain class of practicality (such as such-and-such perception being involved with a noun with letters R, E and D) .

About 3 your memories aqre not given by some outswide actor. They were crafted by you so you know their format and the circumstances where you would create them. If you call a hitpoint a smeerph, it doesn't still make memories about smeerphs "false". It has to be given also that memories are also one possibly confusing and distracting part of qualia-jungle. Maybe you are experiencing your feelings of anxiety when you are remembering an object as big. But how can it be said that such a memory would be wrong when there is no strict demand to interpret memories to only be about physical size? Ie given proper relation to what mental mechnisms generate them memories can only be correct because mental notekeeping strategies are freely chooseable.

Sure, everything you made sense within your frame of reference, but there are no privileged frames of reference. Indeed, proving that there are privileged frames of reference requires a privileged frame of reference and is thus an impossible philosophical act. I can't prove anything I just said, which proves my point, depending on whether you think it did or not.

Also, I've asked my philosophy professor pretty much the same question and he referred me to Hegel. I'm probably terribly misinterpreting what he said but here it is: the awareness of the impossibility of knowledge gives us some kind of meta-knowledge which somehow gets nicely dealt with, and apparently allows for at least some knowledge.

Related discussion on SSC.

“One has knowledge of one’s own percepts.” Percepts are often given epistemic privileges, meaning that they need no justification to be known, but I see no justification for giving them epistemic privileges. It seems like the dark side of epistemology to me.

Why? I realize that Yudkowsky isn't the most coherent writer in the universe, but how the heck did you get from here to there?

A simple qualia-based argument against skepticism (i.e. percepts are simply there and can't be argued with) is problematic- even if you conceded direct knowledge of percepts, you couldn't really know that you had such knowledge. They do not deal with rationality and there aren't any premises you could create from them. It seems less of a foundational tree of justification than a collection of meaningless smells, sounds and colors.

This doesn't mean that there are no qualia-based arguments that are worth looking at; in fact I think it is the most fruitful path to epistemic justification. I'm just trying to explain (what I think is) your objection more properly.