Can we know that something doesn't exist?

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hue-man
 
Reply Wed 24 Feb, 2010 02:10 pm
Can we ever be positively (not absolutely) certain that any particular thing doesn't exist?
 
kennethamy
 
Reply Wed 24 Feb, 2010 02:12 pm
@hue-man,
hue-man;131923 wrote:
Can we ever know that any particular thing doesn't exist?


We know that no unicorn exists because we know there are no unicorns.

---------- Post added 02-24-2010 at 03:13 PM ----------

hue-man;131923 wrote:
Can we ever be positively (not absolutely) certain that any particular thing doesn't exist?


What does "positively certain" mean?
 
Krumple
 
Reply Wed 24 Feb, 2010 02:18 pm
@hue-man,
hue-man;131923 wrote:
Can we ever be positively (not absolutely) certain that any particular thing doesn't exist?


No, but check enough times and chances are it won't show up. We actually operate on this premise every single day of our lives. Just look at what we do when we about to cross the street. We don't just assume and step off the curb, we analyze the situation unless we are children who don't understand the concept to begin with. Anyways we selectively deduce the risk and safety of the situation and then make a choice based on the information we have collected. We make a rational decision. However if you place some uncertainty into the problem, like make the cars invisible, you can never actually arrive at a conclusion. Instead you would just have to guess when it is safe or unsafe. You could use some other sense like hearing the invisible cars but what if the cars were impervious to all senses? How could you make a decision? You can't rationally.

In the real world we only operate on this kind of information, but as soon as you start to talk about things that you can't directly experience with the senses then there is no way to verify it rationally. So we can safely say that something unverifiable probably doesn't exist. Just like you don't see flying pink elephants.
 
hue-man
 
Reply Wed 24 Feb, 2010 02:22 pm
@kennethamy,
kennethamy;131924 wrote:
We know that no unicorn exists because we know there are no unicorns.
I should have been more specific. Can we know that an invisible unicorn doesn't exist?

kennethamy;131924 wrote:
What does "positively certain" mean?


I changed it from know to positively certain after posting. By positively certain I mean can we verify that something doesn't exist by means of empirical study or logical decidability. Can we know that unicorns don't exist on a another planet in a galaxy far far away?

---------- Post added 02-24-2010 at 03:24 PM ----------

Krumple;131928 wrote:
No, but check enough times and chances are it won't show up. We actually operate on this premise every single day of our lives. Just look at what we do when we about to cross the street. We don't just assume and step off the curb, we analyze the situation unless we are children who don't understand the concept to begin with. Anyways we selectively deduce the risk and safety of the situation and then make a choice based on the information we have collected. We make a rational decision. However if you place some uncertainty into the problem, like make the cars invisible, you can never actually arrive at a conclusion. Instead you would just have to guess when it is safe or unsafe. You could use some other sense like hearing the invisible cars but what if the cars were impervious to all senses? How could you make a decision? You can't rationally.

In the real world we only operate on this kind of information, but as soon as you start to talk about things that you can't directly experience with the senses then there is no way to verify it rationally. So we can safely say that something unverifiable probably doesn't exist. Just like you don't see flying pink elephants.


Indeed, but this means that it becomes a matter of belief and not a matter of knowledge, correct?
 
Krumple
 
Reply Wed 24 Feb, 2010 02:37 pm
@hue-man,
hue-man;131930 wrote:
Indeed, but this means that it becomes a matter of belief and not a matter of knowledge, correct?


For the most part yes, but something peculiar happens with us humans. When we hear a lie enough times, we tend to believe it as if it were verifiable. We take it to be a fact even if it has never been rationally investigated to be true. Then it get's called knowledge even when it's not. So belief and knowledge are tricky and sometimes bad words.
 
Pyrrho
 
Reply Wed 24 Feb, 2010 09:01 pm
@hue-man,
hue-man;131923 wrote:
Can we ever be positively (not absolutely) certain that any particular thing doesn't exist?



Yes. We can know that there are no round squares.


hue-man;131930 wrote:
I should have been more specific. Can we know that an invisible unicorn doesn't exist?



Yes. We know this for a variety of reasons. First of all, things that are invisible are still detectable. We can detect air that is invisible to us. Second, an invisible unicorn would be problematic from the standpoint of the possible materials that it could be, and from the fact that eyes require non-invisible parts in order to function.

Now, if you go further, and start to ask about something that is not detectable in any way, then I will respond with saying that you are really and literally talking about nothing.


hue-man;131930 wrote:
I changed it from know to positively certain after posting. By positively certain I mean can we verify that something doesn't exist by means of empirical study or logical decidability. Can we know that unicorns don't exist on a another planet in a galaxy far far away?.
...



If by "unicorn", you mean a horselike animal with a single horn, then we do not know if any such things exist on a remote planet. But we do know that they do not exist here. By "we", of course, I do not mean absolutely every person, as some people are stupid, crazy, ignorant, and/or other things that may prevent them from knowing such things. There are people with silly beliefs who ought to know better, but they do not. But as far as what life, if any, exists on remote planets, we are not in a position to say much about it, unless the proposed thing is impossible.
 
jgweed
 
Reply Thu 25 Feb, 2010 07:22 am
@hue-man,
Aristotle wrote that you cannot have a science (knowledge) of non-being.
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 07:37 am
@jgweed,
 
kennethamy
 
Reply Thu 25 Feb, 2010 07:42 am
@hue-man,
hue-man;131930 wrote:
I should have been more specific. Can we know that an invisible unicorn doesn't exist?



I changed it from know to positively certain after posting. By positively certain I mean can we verify that something doesn't exist by means of empirical study or logical decidability. Can we know that unicorns don't exist on a another planet in a galaxy far far away?

---------- Post added 02-24-2010 at 03:24 PM ----------



Indeed, but this means that it becomes a matter of belief and not a matter of knowledge, correct?



If we know there are no unicorns, then we know that there are no invisible unicorns.

If we know there are no unicorns, then we know there are no unicorns in some different galaxy.

All knowledge is also belief. We cannot know something unless we also believe it. But knowledge is not only a matter of belief, it is a matter of true belief, and it is a matter of justified belief. Why wouldn't you think that we have true justified belief that there are no unicorns?

Let me add that although I know there are no unicorns, it might turn out that I only believed I know there are no unicorns, but I was wrong. Of course, that goes without saying, since I am a fallible human being.
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 07:48 am
@kennethamy,
 
kennethamy
 
Reply Thu 25 Feb, 2010 07:56 am
@Fil Albuquerque,
Fil. Albuquerque;132270 wrote:
The idea of unicorn itself posits the opposite...there are Unicorns !
.


What can that mean?
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 07:59 am
@kennethamy,
kennethamy;132273 wrote:
What can that mean?


That we are refering to something rather then nothing !...Smile
 
kennethamy
 
Reply Thu 25 Feb, 2010 08:02 am
@Fil Albuquerque,
Fil. Albuquerque;132274 wrote:
That we are refering to something rather then nothing !...Smile


So, when I talk about The Spaghetti Monster roaming the skies above?
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 08:09 am
@kennethamy,
kennethamy;132277 wrote:
So, when I talk about The Spaghetti Monster roaming the skies above?
 
kennethamy
 
Reply Thu 25 Feb, 2010 08:37 am
@Fil Albuquerque,
Fil. Albuquerque;132281 wrote:


In other words, you are not being serious. Note to Jgweed, it is pretending to be serious, but not being serious, that annoys me most in posts.
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 08:41 am
@kennethamy,
kennethamy;132289 wrote:
In other words, you are not being serious. Note to Jgweed, it is pretending to be serious, but not being serious, that annoys me most in posts.
 
kennethamy
 
Reply Thu 25 Feb, 2010 08:46 am
@Fil Albuquerque,
Fil. Albuquerque;132291 wrote:


You think that the Spaghetti Monster disguises himself? How clever of him. He may be the next F16 we see!
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 10:02 am
@kennethamy,
kennethamy;132294 wrote:
You think that the Spaghetti Monster disguises himself? How clever of him. He may be the next F16 we see!


...hummm !...:rolleyes: ...consider the Spaghetti Monster a lesser form of "Artificial Intelligence"... while you may be a higher, more organized, information packaged... :a-ok: (Nevertheless X is always something rather then nothing...)
 
kennethamy
 
Reply Thu 25 Feb, 2010 10:14 am
@Fil Albuquerque,
Fil. Albuquerque;132315 wrote:
...hummm !...:rolleyes: ...consider the Spaghetti Monster a lesser form of "Artificial Intelligence"... while you may be a higher, more organized, information packaged... :a-ok: (Nevertheless X is always something rather then nothing...)


Uh, what does the symbol "X" mean? I agree that if there is an X then X exists. That is, if something exists, then something exists. But, does that something exist? Just because there is a word, it does not follow that there is anything named by that word. In other words, the argument:

1. The word "X" exists,
Therefore, 2.X exists.

Is an invalid argument.

(It is important to distinguish between "X" and X).
 
Fil Albuquerque
 
Reply Thu 25 Feb, 2010 10:27 am
@kennethamy,
kennethamy;132322 wrote:
Uh, what does the symbol "X" mean? I agree that if there is an X then X exists. That is, if something exists, then something exists. But, does that something exist? Just because there is a word, it does not follow that there is anything named by that word. In other words, the argument:

1. The word "X" exists,
Therefore, 2.X exists.

Is an invalid argument.

(It is important to distinguish between "X" and X).


---------- Post added 02-25-2010 at 11:29 AM ----------

...now X and Y may not have the same level of complexity, I give you that...(they are not transcendent only transcendental)

---------- Post added 02-25-2010 at 11:32 AM ----------



---------- Post added 02-25-2010 at 11:40 AM ----------



---------- Post added 02-25-2010 at 11:55 AM ----------

...the problem might be in the nature of what we usually call error...does error refers to nothing ? or to something unsufficiently clarified ?
...in my view error is X not nothing...same is to say that true error is a fallacy...Universe is Perfect ! How could not be ?
...Being is defined, therefore finished and Perfect...you as a Logician should know better...(and we were speaking inside Being how could we not ?)

---------- Post added 02-25-2010 at 12:00 PM ----------

 
 

 
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