#### Posers and Puzzles

ark13
Posers and Puzzles 09 Apr '05 01:03
1. ark13
Enola Straight
09 Apr '05 01:03
This will give you something to think about.

Suppose someone makes the claim that "All crows are black." If just three or four black crows are seen, that claim is weakly confirmed. But if millions are seen, it strongly confirms it. Now this can easily transfered into the logically equivalant form, "All non-black objects are not crows." But does that mean that seeing a yellow caterpillar, or a purple cow helps prove that "All crows are black?"

I believe so. What do you think?
2. 09 Apr '05 02:56
Originally posted by ark13
This will give you something to think about.

Suppose someone makes the claim that "All crows are black." If just three or four black crows are seen, that claim is weakly confirmed. But if millions are seen, it strongly confirms it. Now this can easily transfered into the logically equivalant form, "All non-black objects are not crows." But does that ...[text shortened]... , or a purple cow helps prove that "All crows are black?"

I believe so. What do you think?
I agree that it also helps build the proof that "all crows are black". I base this on this logic: to prove all crows are black, we need to either show that 1. all crows are black (obviously) or 2. all non-black objects are not crows.

There are probably a whole lot more non-black objects than there are crows (so #2 is probably not the best way to go), but the number is finite. So seeing one does help build (at least a little bit) the case that all non-black objects are not crows. In that sense, it does help the proof.

although you could probably also argue that there are so many non-black objects that no one could possible see and classify them all, so that seeing one non-black object doesn't help you get to the full proof. Still, seeing the non-black non-crow object doesn't disprove the claim that all crows are black, and so in that sense it may strengthen the claim that all crows are black.

It's a good question...never really thought about it that way...i'm sure the arguments could go deeper and deeper down a bottomless pit...
3. Bowmann
Non-Subscriber
09 Apr '05 15:17
Originally posted by ark13
This will give you something to think about.

Suppose someone makes the claim that "All crows are black." If just three or four black crows are seen, that claim is weakly confirmed. But if millions are seen, it strongly confirms it. Now this can easily transfered into the logically equivalant form, "All non-black objects are not crows." But does that ...[text shortened]... , or a purple cow helps prove that "All crows are black?"

I believe so. What do you think?
It would provide further evidence, but help to "prove" nothing.
4. ark13
Enola Straight
10 Apr '05 17:48
Originally posted by Bowmann
It would provide further evidence, but help to "prove" nothing.
That's what I meant. Seeing a non-black object that isn't a crow could provide further evidence for the law.
5. theangrystudent
I am MIGHTY!
10 Apr '05 18:00
Originally posted by ark13
That's what I meant. Seeing a non-black object that isn't a crow could provide further evidence for the law.
You cannot prove laws by example(s).
6. ark13
Enola Straight
11 Apr '05 00:00
Yes, I know. That's why I said provide further evidence for...

But of course, finding that every example is true would prove it. So finding one example is on the way to proving it.
7. Palynka
Upward Spiral
11 Apr '05 00:16
Actually, the paradox is that this line of reasoning leads you to conclude that nothing is "provable" through evidence alone.

It is impossible to confirm that all non-black objects are not crows, therefore it is impossible to prove that all crows are black.

ðŸ™„
8. ark13
Enola Straight
11 Apr '05 00:39
Originally posted by Palynka
Actually, the paradox is that this line of reasoning leads you to conclude that nothing is "provable" through evidence alone.

It is impossible to confirm that all non-black objects are not crows, therefore it is impossible to prove that all crows are black.

ðŸ™„
Yes, realistically, it's impossible to prove that all non-black objects aren't crows, but that's not the point. If the law to be proved was instead "All crows in my room are black." Then that could be translated to, "All non-black objects in my room aren't crows." And that could be proven realively easily. It's not the fact that it's impossible to find all non-black objects that's of interest. It's whether or not the finding of one increases the chance of the law being true.
9. Palynka
Upward Spiral
11 Apr '05 13:25
Originally posted by ark13
Yes, realistically, it's impossible to prove that all non-black objects aren't crows, but that's not the point. If the law to be proved was instead "All crows in my room are black." Then that could be translated to, "All non-black objects in my room aren't crows." And that could be proven realively easily. It's not the fact that it's impossible to ...[text shortened]... f interest. It's whether or not the finding of one increases the chance of the law being true.
But then you are changing the situation. In your new case, there's no need for samples as the whole universe (your room) is being considered.

In your original case, the relevant elements in the universe (the crows) are a very very small group in a near infinite number of elements. If in fact we consider them infinite, then mathematically it would not prove anything. They are indeed finite but there is such a residual effect that it is almost zero.

It's a bit like 1-0,999999(9)...=0. Mathematically this is true, yet, IMO, it falls under the same paradox.
10. Bowmann
Non-Subscriber
11 Apr '05 14:03
Originally posted by ark13
Yes, realistically, it's impossible to prove that all non-black objects aren't crows, but that's not the point. If the law to be proved was instead "All crows in my room are black." Then that could be translated to, "All non-black objects in my room aren't crows." And that could be proven realively easily. It's not the fact that it's impossible to ...[text shortened]... f interest. It's whether or not the finding of one increases the chance of the law being true.
But you keep changing your argument.
11. Alcra
Lazy Sod
11 Apr '05 14:42
It IS possible, but not probable, that it can be proven that all crows are black (or not), since the number of crows is finite. Finding all of them though is improbable.

The corollary (correct word?) is not probable or possible, since the number of non-crow objects is NOT finite, as argued earlier. In the entire universe, their are an infinite number of objects. However, if we restrict our space to Earth alone, then yes, the second argument helps "prove" the first.

A layman to statistical thinking,
alcra
12. Palynka
Upward Spiral
11 Apr '05 14:55
Originally posted by Alcra
It IS possible, but not probable, that it can be proven that all crows are black (or not), since the number of crows is finite. Finding all of them though is improbable.

The corollary (correct word?) is not probable or possible, since the number of non-crow objects is NOT finite, as argued earlier. In the entire universe, their are an infinite number of obj ...[text shortened]... es, the second argument helps "prove" the first.

A layman to statistical thinking,
alcra
Finding all crows would prove that all non-black objects are not crows, because you accounted for ALL the crows.
13. Bowmann
Non-Subscriber
11 Apr '05 22:55
Originally posted by Alcra
In the entire universe, their are an infinite number of objects.
Who told you that?
14. Palynka
Upward Spiral
11 Apr '05 23:23
Much I marvelled this ungainly fowl to hear discourse so plainly,
Though its answer little meaning, little relevancy bore;
For we cannot help agreeing that no living human being
Ever yet was blessed with seeing bird above his chamber door,
Bird or beast upon the sculptured bust above his chamber door,
With such name as "Nevermore."

15. ark13
Enola Straight
12 Apr '05 00:42
Originally posted by Bowmann
But you keep changing your argument.
I'm not changing my argument. In fact, I wasn't aware I had an argument. This whole time I've been trying to clarify this problem and simply play the devil's avdocate. When I gave the example with my room, it was an oversimplification. But if we consider the universe to have a finite amount of objects, it is truly the same as the initial problem. I only asked, would finding a non-black, non-crow object slightly (however small) increases the likelyhood that the law, "All crows are black," is true. And if the universe, as my room, has a finite amount of "stuff" then I believe this to be true. And it seems that most people agree with this.