What is a "dream" or a "hallucination"?  (Those sound suspiciously like things that would only have meaning if we make judgements based on sense data...)  Isn't saying that our judgements in those cases are wrong an assumption?  How do you know that they are "wrong"?

You're making an assertion, that definition and logic are apart from sense data judgement.  But I'm asking you how do you know that they are apart?  And also, why do you assume that such judgements are different in character from the decisions you make based on logic or definition?

Actually, what do you mean by "sense data judgement"?

It's possible that you can.  I suggest you try again.

While composing your reply, hover your cursor around the line of the text box.  At some places on or around the line, it will turn into a four-directional arrow, kind of like a compass rose.  When you see that, click on the text box (you'll know you've done that when you see little open boxes appear along the line of the box) and then copy it (Ctrl-C).  Then, you'll be able to paste (Ctrl-V) the text box into the body of your response whenever you need it.

Or at least, that's how it works for me.

Do you see the part that Sqrl said that you really disagree with?  IMO, this is it:

(logic being a result of our experience with our sensory input)

In my opinion, logic, language, the whole kit-and-caboodle (whatever the hell that means) is "a result of our experience with our sensory input."  Which is why I find your skepticism to be self-contradictory.

And also, that's why I think it really does matter where you think your logic and language come from.  If not from sensory input, then what?

'"What is a "dream" or a "hallucination"?  (Those sound suspiciously like things that would only have meaning if we make judgements based on sense data...)  Isn't saying that our judgements in those cases are wrong an assumption?  How do you know that they are "wrong"?"'

I'm not saying the dreams are right or wrong, just that they contradict our other judgements (when we wake up, we think "Oh, that wasn't real", so we question our own judgements occasionally.  I since we do question them, that means we can question them).

"You're making an assertion, that definition and logic are apart from sense data judgement.  But I'm asking you how do you know that they are apart?  And also, why do you assume that such judgements are different in character from the decisions you make based on logic or definition?

Actually, what do you mean by "sense data judgement"?

Because, by definition, they are apart.  Reality you can question (because it's not self-defeating), whereas logic and definition you cannot (because that would be self defeating (how do you question meaning without using it?)).  I do not assume they are different in charactr, because meaning is immutable, whereas our thoughts concerning reality are certainly not (even apart from my own objections; you, I will guess, have changed your mind about something in reality at least once, right?).  And, by sense data judgement, I mean that deciding certain object exists based upon certain sense data, a decision that arbitrary (and perhaps I should clarify here: I do not mean deciding that the sense data exclusively represents the object you've assumed exists, because it can represent anything).

OK, why did that just start working?  I tried what you suggested before this, and it failed.  Weird.

I disagree; language does not have to be a result of sensory data (a "god" could have put it there, again), and logic must work (otherwise, we'd both be right in this argument ;)  ).   And it doesn't matter if it came from anything; they're systems that have to work and be true.

A.  A belief set most certainly can specify one interpretation of sense data.  I don't think you understand what I'm saying. 

B.  I thought we had already discussed that practicality is not a measurement of absolute truth.

Another way to make a quotebox:

I think that perhaps you've misunderstood the jist of what I've been trying to ask.  You seem to claim that there are two types of data--sense data, and Other (which is some undefined way you believe you acquire language, logic, etc., and that you think is irrelevant to our discussion). 

The judgements based on sense data, you hold to be arbitrary, and inherently "uncertain"; but judgements based on Other, you think can be certain.

Well, how do you know which data is sense data, and which data is Other?  How do you know if one of your judgements is based off of sense data, or if it's based off of Other?  How do you know that sense data is coming from some place that's different from wherever Other is coming from (since you don't know where Other is coming from)?

I think it becomes an arbitrary distinction, unless we posit certain "sensory organs" or certain mechanisms by which we get certain data (like that the sky is blue) but not other data (logic, definition).  But why would we posit sensory organs/mechanisms?  According to your beliefs, I'd find such a supposition arbitrary.

In other words, if we were just "a brain floating in a vat recieving electrical stimuli," then it would seem to me that we should treat all of our judgements equally.  Or don't you think that a brain in a vat could be led to believe that x is equal to not-x? (Hell, I knew some kids in college who thought as much...)

***

And with that, I think I've expressed myself just about as well as I can manage on these topics.  Unless I see something else that calls out and manages to drag me back in, I'll let myself rest for a bit. :)

If I wind up leaving it at this, thank you again for the thought-provoking discussion.

ETA: Oh hell, just a little bit more, for kicks:

I propose a small thought experiment.  Imagine a person born completely insensate--no sight, smell, hearing, etc.  Would such a person know what a "bachelor" was (iirc, an unmarried man, right)?  Would such a person be able to perform simple arithmetic?  Would he know that x = x?

If it seems like he would not know any of those things, then again: where does definition, logic, etc., come from, if not from judgements based on sense data?

A. Unless your advocating that you merely presuppose something about sense data (this is cheese) then you're saying what I think you are: This group of sense data can only indicate cheese to me. And it doesn't. That would be somewhat similar to believing a bachelor is a married man - In that you just can't. And saying it over and over doesn't make it possible.

In the event you are merely presupposing that you know there is cheese about this meaningless group of sense data... we're no longer talking about empiricism... we're talking about the method of presuppositionalism. That's the problem.

 B. I don't think you're understanding that whenever you describe 'practicality' to me it's subliminally implying some sort of knowledge. I really don't take to this dinstinction between 'absolute truth' and just 'sort kinda truth but really isn't'. If your having a 'perception' and you expect 'it' to interact with you in a certain way... that would be something you think you know. It's inescapable. If you don't expect a perception to interact with you a certain way or whatever input/output system you set up, the meaning of practicality, whatever you're making of it, seems illusory to me. 

p4wn3d

A.  "I believe that cheese looks and smells and feels like so.  I further believe that what looks and smells and feels like so is cheese."  These are beliefs.  You appear now to be denying the existence of absolute BELIEF, which is completely different from doubting absolute KNOWLEDGE.  Worse, you just said that having such a belief is a self-contradicting definition, which is not only wrong but nonsensical.  Besides, how do you know how I define the word "bachelor"? 

Belief sets exist that can be contradicted by sense data
"butbutbut you can just believe something else"
Belief sets exist that can be contradicted by sense data
"butbutbut that sense data could actually mean anything if you interpret it differently"
Belief sets exist that can be contradicted by sense data
"butbutbut any specific interpretation is just an assumption"
Belief sets exist that can be contradicted by sense data

To put it more politely, I'm not ADVOCATING that, I'm just saying that it's POSSIBLE to do so, which satisfies my goal of disproving your "ANY" statement. 

B.  But this isn't ABSOLUTE knowledge, it's knowledge within the sense data (input) of its own internal consistency with your output.  Do you deny that when you output what you perceive as "pressing Y on the keyboard" a Y appears on the screen?  Do you not expect that if you should output "pull the trigger of a loaded gun that is pointed at your body" you are going to receive input "PAIN"?  Life may be an illusion, but it is a VERY complete one, which is getting dangerously near to my point.

A. As I understand you're trying to making a point to contradict my "any" statement and I'm apparently not making it clear enough that there's a fundamental problem which would make this clearly an impossible scenario to arrive at.

You pose a person with belief(s) X, then says he also has the belief that sensedataY must indicate Z. (Or however you would correctly transcribe that in this form.) 1. Since we're discussing a method of truth... I wonder how you got belief X in the first place. It just ignores the whole issue of legitimately arriving at a belief which is fundamental to this. 2. Saying that a person can believe that sensedataY must indicate Z is already impossible according to what I'm saying. It goes against an inevitable admission of the intellect (and no, I didn't mean to imply that the belief was contradictory, rather it's wrong by rational analysis). SensedataY is not an indicator of only Z and no other no matter how much you want to assert that someone just believes it is. SensedataY indicates about a million different beliefs. Thus you can't set up this scenario. The point you're trying to make can't happen according to the fundamental problem I'm positing with using sense data to arrive at any belief. I can't ignore that and pretend someone can legitimately believe sensedataY must indicates cheese. That's the issue, so tell me how I'm wrong in saying that since it would make your point impossible to truly occur.

If you held the meaning of bachelor that I do... then the point would come through. I know you can define a word any way you want. I was merely trying to exemplify the kind of problem I'm trying to communicate: similar to contradicting the meaning of your own word. It's in the realm of rationality.

A. and B.

Next, the distinction between belief and 'absolute knowledge' is semantics and, I'd add, what allows the subjectivist generation to revel in contradiction - have their cake and eat it. Unfortunately, explaining this only gives it undo attention. When I person says they believe something... it means they believe it's the right belief... and that inevitably means they think the other opposing beliefs are not the right beliefs. They believe they know something... they believe they know the things it's not. Go figure, that's not much different of how philosophers have described so-called 'absolute truth'. Knowing that you know something without other possibilities being true. Whether people legitimately arrive at that place... it's just what is meant when they say it.

This example might not be as effective as my explanation: "I believe Z and also that A - Y are demonstratively false. ...Oh, but I'm not saying I know that." (???)

The only thing I can gather with the use of "belief vs. knowledge" is that, through this, people are either 1. exposing the fact that they're really not so sure they believe something in the first place or 2. that by making this distinction for themselves they don't feel obligated to make an account or case for it (mainly because they know they can't or don't want to lol) 3. there's ambiguity since we use the word 'belief' to describe someone elses 'knowledge' which we think isn't actually knowledge at all.

Touching on point B through this - however you decide to name the "consciousness" of interactions with various sense data, it's just going to mean some sort of knowledge. When I know to hit "Y" on the keyboard to make it show up on the screen... that's right, I don't believe I came to know that through sense data. Again, there are other methods of truth proposed.

Pardon me if I'm coming across abrasively.  I'm only going for emphasis :)