Can we know that something doesn't exist?

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kennethamy
 
Reply Fri 26 Feb, 2010 09:08 am
@Zetherin,
Zetherin;132822 wrote:
I believe that's what he meant. He was hinting towards logical posivitism.



This I don't understand. You're basically saying here that facts are not true, since facts are what make up synthetic propositions. And so, you don't think anything we say about the world can be true.

I'm sure you can see the glaring issues of holding this sort of position, right?


But doesn't he agree that the sentence that ETs exist is true or false? How could he not?

I don't think that he said anything about facts, though. And isn't "true fact" a pleonasm? A redundancy? Must not all facts be true? Can there be a false fact?
 
Zetherin
 
Reply Fri 26 Feb, 2010 09:14 am
@hue-man,
kennethamy wrote:
But doesn't he agree that the sentence that ETs exist is true or false? How could he not?


I would hope so.

Quote:

I don't think that he said anything about facts, though. And isn't "true fact" a pleonasm? A redundancy? Must not all facts be true? Can there be a false fact?


Right. It seems he believes we do not have the capacity to discover facts about the world, as he believes no synthetic propositions can be true.
 
kennethamy
 
Reply Fri 26 Feb, 2010 09:20 am
@Zetherin,
Zetherin;132824 wrote:




Right. It seems he believes we do not have the capacity to discover facts about the world, as he believes no synthetic propositions can be true.


Well that is not clear. He may just think we cannot know that any synthetic proposition is true. But I really don't know what his view is.
 
hue-man
 
Reply Fri 26 Feb, 2010 09:41 am
@kennethamy,
kennethamy;132819 wrote:
It seems to me that now you are left with explaining what it means to say that a proposition serves no function as a proposition. For example, it seems to me that one function as a proposition is to serve as either a premise or conclusion of an argument. But, you cannot mean that about the proposition that ETs exist. In what way does not that proposition not serve any function as a proposition? The positivists meant by calling a sentence meaningless that the sentence had no truth value, not that it could not be proven true, since a sentence may have truth value and not be provably true. Like the sentence, "ETs exist".


The proposition that ET's exist serves no function as a proposition if it cannot be proven to be true or false. A proposition is a statement that holds truth value (meaning that it can be verified to be true or false). If someone says that something is true, and yet they cannot verify it, then that person is making a proposition that has no truth value. A proposition with no truth value isn't really a proposition at all.

kennethamy;132819 wrote:
In what way does sound reasoning not imply that what we reason about soundly is not known to be true? Don't I know that Socrates is mortal if it follows from the premises I know to be true, and a valid argument? Or don't I know that Socrates is mortal because we have ample evidence that no man lives forever?


Sound reasoning, or logic, doesn't imply that what we reason about is true if the premise is a synthetic proposition. You know that Socrates was mortal because Socrates is dead. The proposition that humans are mortal has been verified by empirical study.

---------- Post added 02-26-2010 at 10:44 AM ----------

Zetherin;132822 wrote:
This I don't understand. You're basically saying here that facts are not true, since facts are what make up synthetic propositions. And so, you don't think anything we say about the world can be true.

I'm sure you can see the glaring issues of holding this sort of position, right?


How am I saying that facts are not true? I'm saying that logic doesn't equal knowledge for a synthetic proposition. Facts are only known to be facts if they have been verified.

---------- Post added 02-26-2010 at 10:47 AM ----------

kennethamy;132823 wrote:
But doesn't he agree that the sentence that ETs exist is true or false? How could he not?

I don't think that he said anything about facts, though. And isn't "true fact" a pleonasm? A redundancy? Must not all facts be true? Can there be a false fact?


You misunderstand what I'm saying. I agree that the sentence "ETs exist" is either true or false. What I'm saying is that we have no way of verifying that the sentence "ETs exist" is true or false, and therefore the statement cannot serve as a meaningful proposition. Maybe one day it will, but not yet. My argument is semantic.
 
Zetherin
 
Reply Fri 26 Feb, 2010 09:50 am
@hue-man,
hue-man wrote:

How am I saying that facts are not true? I'm saying that logic doesn't equal knowledge for a synthetic proposition. Facts are only known to be facts if they have been verified.


Because facts make up synthetic propositions. And you have stated, "and so reason doesn't equate to knowledge or truth in my eyes when dealing with a synthetic proposition.", which I thought meant that you thought synthetic propositions cannot be true. Did I misunderstand you?

Quote:
Sound reasoning, or logic, doesn't imply that what we reason about is true if the premise is a synthetic proposition. You know that Socrates was mortal because Socrates is dead. The proposition that humans are mortal has been verified by empirical study.


Sure, but that doesn't matter. A synthetic proposition can still be true, even if we don't know it's true.

 
kennethamy
 
Reply Fri 26 Feb, 2010 09:51 am
@hue-man,
hue-man;132840 wrote:
The proposition that ET's exist serves no function as a proposition if it cannot be proven to be true or false. A proposition is a statement that holds truth value (meaning that it can be verified to be true or false). If someone says that something is true, and yet they cannot verify it, then that person is making a proposition that has no truth value. A proposition with no truth value isn't really a proposition at all.



Sound reasoning, or logic, doesn't imply that what we reason about is true if the premise is a synthetic proposition. You know that Socrates was mortal because Socrates is dead. The proposition that humans are mortal has been verified by empirical study.


Why would you think that unless we can verify a proposition, that it has no truth value. We cannot verify whether the number of stars in the universe is odd or even. Do you think that the statement that the number of stars in the universe is even is neither true nor false? What is the argument for saying that unless you can know what the truth value of a proposition is, it has no truth value, which is what you seem to be saying. At one time we did not know whether a ninth planet existed. Does that mean that the proposition "A ninth planet exists" had no truth value, or that it was meaningless? And that it acquired meaning, and a truth value only when we discovered Pluto?

Any statement that implies what is false is itself, false. A true statement cannot imply a false statement. Logic rule #1
 
hue-man
 
Reply Fri 26 Feb, 2010 09:55 am
@Zetherin,
Zetherin;132848 wrote:
Because facts make up synthetic propositions. And you have stated, "and so reason doesn't equate to knowledge or truth in my eyes when dealing with a synthetic proposition.", which I thought meant that you thought synthetic propositions cannot be true. Did I misunderstand you?


Yes. You misunderstood me.

Zetherin;132848 wrote:
A synthetic proposition can still be true, even if we don't know it's true.
I didn't state the contrary.
 
Zetherin
 
Reply Fri 26 Feb, 2010 09:58 am
@hue-man,
hue-man;132855 wrote:
Yes. You misunderstood me.

I didn't state the contrary.


Alright, let me see if this is your correct position:

If a synthetic proposition has not been verified to be true or false, it is a meaningless proposition. The proposition acquires meaning after verification.

Is this right?
 
Night Ripper
 
Reply Fri 26 Feb, 2010 10:03 am
@Pyrrho,
Pyrrho;132163 wrote:
Yes. We can know that there are no round squares.


Actually, different geometries can allow for that but I get what your point was supposed to be. You're trying to identify something as containing a contradiction. A better example would be to say that there are no married bachelors.

However, most people haven't thought about exactly what this means. It doesn't actually tell us anything about what exists or does not exist. It tells us that the phrase "married bachelor" doesn't refer to anything. It would have to first refer to something before we could determine that the referent exists (by observing it) or probably doesn't exist (by never observing it).

Logical contradictions tell us about conceivability. If we can't conceive of what we're talking about then there's nothing to conceive the existence or non-existence of.
 
kennethamy
 
Reply Fri 26 Feb, 2010 10:08 am
@Night Ripper,
Night Ripper;132859 wrote:


However, most people haven't thought about exactly what this means. It doesn't actually tell us anything about what exists or does not exist. It tells us that the phrase "married bachelor" doesn't refer to anything.


What is the difference between saying that there are no married bachelors, and that, the term, "married bachelor" does not refer to anything? The first is in what Rudolf Carnap called, "the material mode of speech", and the second in what he called, "the formal mode of speech". They both come to the same thing.

A term would have to refer to something before we could tell that it refers. But not before we could tell whether it refers.
 
Night Ripper
 
Reply Fri 26 Feb, 2010 10:20 am
@kennethamy,
kennethamy;132862 wrote:
What is the difference between saying that there are no married bachelors, and that, the term, "married bachelor" does not refer to anything? The first is in what Rudolf Carnap called, "the material mode of speech", and the second in what he called, "the formal mode of speech". They both come to the same thing.

A term would have to refer to something before we could tell that it refers. But not before we could tell whether it refers.


Well, I might mean something different by refer than you do so let me clarify. While there are no unicorns, the term unicorn does refer to a concept, something of which we can conceive. In this case, there is a difference between saying unicorns don't exist and saying that the word "unicorn" doesn't refer to anything.
 
kennethamy
 
Reply Fri 26 Feb, 2010 10:46 am
@Night Ripper,
Night Ripper;132866 wrote:
Well, I might mean something different by refer than you do so let me clarify. While there are no unicorns, the term unicorn does refer to a concept, something of which we can conceive. In this case, there is a difference between saying unicorns don't exist and saying that the word "unicorn" doesn't refer to anything.


If the term, "unicorn" refers to a concept, then what do you think that the term, "the concept of unicorn" refers to? Also a concept? The term, "unicorn" fails to refer, but it it did refer, it would refer to an equine like animal, with one horn on its forehead, and which had magical powers. There is no such beast, so the term, 'unicorn' fails to refer. It is really not cricket to argue that since the word "X" fails to refer because there are no "Xs", that, nevertheless, it refers anyway because it refers to the concept of X. In the used car business, that kind of move is called, "bait and switch". And on the street corner, "Two Card Monte'".
 
Night Ripper
 
Reply Fri 26 Feb, 2010 11:49 am
@kennethamy,
The word "unicorn" refers to a concept but that concept is not instantiated. The phrase "married bachelor" doesn't refer to a concept. Therefore, there is no concept to be instantiated. That's the difference.
 
kennethamy
 
Reply Fri 26 Feb, 2010 12:09 pm
@Night Ripper,
Night Ripper;132894 wrote:
The word "unicorn" refers to a concept but that concept is not instantiated. The phrase "married bachelor" doesn't refer to a concept. Therefore, there is no concept to be instantiated. That's the difference.


But why to you say that "unicorn" refers to a concept? Because there are no unicorns? Why is that a reason? Is the assumption this: that all words must refer, and if they do not refer to what they are supposed to refer to, then they have to refer to something else? But why choose the concept of unicorn to refer to? Why not, a painting of a unicorn? Or a sculpture of a unicorn, for the word "unicorn" to refer to. Or, instead, why not question your assumption that all words have to refer, and in particular, that the word, "unicorn" has to refer? The word, "if" does not refer to anything, does it? Or do you think there are ifs it refers to? Or, the concept of if, perhaps?
 
Night Ripper
 
Reply Fri 26 Feb, 2010 12:21 pm
@kennethamy,
kennethamy;132897 wrote:
But why to you say that "unicorn" refers to a concept? Because there are no unicorns?


No.

kennethamy;132897 wrote:
Is the assumption this: that all words must refer, and if they do not refer to what they are supposed to refer to, then they have to refer to something else?


No, all words must refer to a concept if they are to mean anything.

kennethamy;132897 wrote:
The word, "if" does not refer to anything, does it? Or do you think there are ifs it refers to? Or, the concept of if, perhaps?


Yes, the word "if" refers to the concept of "if". Understanding how to use the word "if" in a sentence is understanding the concept of "if".

All words that have meaning refer to concepts. The words "married" and "bachelor", individually, have meaning because they each refer to concepts. However, taken together they exclude each other so as to refer to nothing at all.
 
kennethamy
 
Reply Fri 26 Feb, 2010 12:39 pm
@Night Ripper,
Night Ripper;132902 wrote:
No.



No, all words must refer to a concept if they are to mean anything.



Yes, the word "if" refers to the concept of if. Understanding how to use the word "if" in a sentence is understanding the concept of "if".

All words that have meaning refer to concepts. The words "married" and "bachelor", individually, have meaning because they each refer to concepts. However, taken together they exclude each other so as to refer to nothing at all.


You mean that the term "elephant" refers to the concept of elephant and not to elephants? Well, I asked you about the word, "if". What is the concept of "if"? And what is your evidence for the theory of meaning that words refer to concepts? Let's suppose, as is true, that I don't have any concept of tensor calculus. I don't know what it is. However, suppose I say that tensor calculus is a branch of mathematics. Are you saying that sentence does not mean anything when uttered by me? Isn't it true? And, if it is true, doesn't it mean something? Suppose I tell a person who does not know much English that there are giraffes in a certain place along with other animals. He asks, "what are you referring to?" and I reply by pointing to a giraffe. Should I have pointed to my head instead? That is where the concept of giraffe is, after all. And, to repeat an old question, if "elephant" refers to the concept of elephant (as you say) then what does "the concept of elephant" refer to? Also, the concept of elephant?
 
Night Ripper
 
Reply Fri 26 Feb, 2010 01:05 pm
@kennethamy,
kennethamy;132906 wrote:
You mean that the term "elephant" refers to the concept of elephant and not to elephants?


In this context "elephants" is just another way of saying "the concept of elephant". So, the question is nonsensical.

kennethamy;132906 wrote:
Well, I asked you about the word, "if". What is the concept of "if"?


If you don't understand the concept of "if", I'm pretty much wasting my time typing this.

kennethamy;132906 wrote:
And what is your evidence for the theory of meaning that words refer to concepts?


It seems obvious. If you can name a word that means something but doesn't refer to a concept then tell me what it is.

kennethamy;132906 wrote:
Let's suppose, as is true, that I don't have any concept of tensor calculus. I don't know what it is. However, suppose I say that tensor calculus is a branch of mathematics.


But you do have a concept of "tensor calculus". You just said it, "a branch of mathematics".

kennethamy;132906 wrote:
Suppose I tell a person who does not know much English that there are giraffes in a certain place along with other animals. He asks, "what are you referring to?" and I reply by pointing to a giraffe. Should I have pointed to my head instead? That is where the concept of giraffe is, after all.


The word "giraffe" refers to the concept of "giraffe" but he's not asking that. He's really asking what the concept of "giraffe" is, which is instantiated by an actual giraffe. That's why pointing at your head would be foolish.

Also, (Wittgenstein covers this), just showing a single picture of a giraffe might not be enough to get the same concept as you. Is the picture the giraffe? Is it the trees in the picture? Is it the thing drinking water? Learning a concept is heuristic.


kennethamy;132906 wrote:
And, to repeat an old question, if "elephant" refers to the concept of elephant (as you say) then what does "the concept of elephant" refer to? Also, the concept of elephant?


No, it refers to the concept of the concept of "elephant". There's concepts, the concepts of concepts, and so on...
 
north
 
Reply Fri 26 Feb, 2010 04:55 pm
@Night Ripper,
Can we know that something doesn't exist?

yes

because all forms have limits

as does the Universe
 
Fil Albuquerque
 
Reply Fri 26 Feb, 2010 05:14 pm
@kennethamy,
kennethamy;132871 wrote:
If the term, "unicorn" refers to a concept, then what do you think that the term, "the concept of unicorn" refers to? Also a concept? The term, "unicorn" fails to refer, but it it did refer, it would refer to an equine like animal, with one horn on its forehead, and which had magical powers. There is no such beast, so the term, 'unicorn' fails to refer. It is really not cricket to argue that since the word "X" fails to refer because there are no "Xs", that, nevertheless, it refers anyway because it refers to the concept of X. In the used car business, that kind of move is called, "bait and switch". And on the street corner, "Two Card Monte'".


Here is were exactly you get it all wrong...you cannot refer but to perceptions and concepts not stimuli...and yes the all thing is a construction upon construction...
 
hue-man
 
Reply Fri 26 Feb, 2010 05:17 pm
@Zetherin,
Zetherin;132858 wrote:
Alright, let me see if this is your correct position:

If a synthetic proposition has not been verified to be true or false, it is a meaningless proposition. The proposition acquires meaning after verification.

Is this right?


My position is that a proposition acquires meaning or substance if it is at least able to verified to begin with.

---------- Post added 02-26-2010 at 07:13 PM ----------

kennethamy;132849 wrote:
Why would you think that unless we can verify a proposition, that it has no truth value. We cannot verify whether the number of stars in the universe is odd or even. Do you think that the statement that the number of stars in the universe is even is neither true nor false? What is the argument for saying that unless you can know what the truth value of a proposition is, it has no truth value, which is what you seem to be saying. At one time we did not know whether a ninth planet existed. Does that mean that the proposition "A ninth planet exists" had no truth value, or that it was meaningless? And that it acquired meaning, and a truth value only when we discovered Pluto?

Any statement that implies what is false is itself, false. A true statement cannot imply a false statement. Logic rule #1


You're misunderstanding me. I'm saying that a sentence can only serve as a substantial (or meaningful) proposition if it is able to be verified. I'm not saying that it only becomes meaningful after it has been verified.

For example: If someone were to say that "there is a tenth planet", and yet they could not prove that such a statement were true, then their proposition serves no meaningful function as a proposition because it cannot be proven to be true. Of course such a statement would have to either be true or false in reality, but my argument is not metaphysical. My argument is epistemic and semantic.
 
 

 
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