Does "All I know are ..." = "I don't know any ..."?

[Curious George]

In your opinion, would it be good to reject misleading statements?

In my opinion it is good to recognize misleading statements. To discern a person’s intent can be more difficult. Were they attempting a joke? Attempting dishonesty? Trying to defend a position and grasping at anything to do so? Attempting to say something without actually saying anything?

People are complicated. And while it is good to recognize misleading statements, it is best not to let statements on the internet live rent free in your head for too long.

 

[dybmh]

I would suggest the statement all I know x that I know and none of x that I know are completely irrelevant statements when you know zero x. It is like telling your only child that they are your favorite child. While it can be humorous because it is a meaningless statement that seems meaningful, the second part of the statement renders the first irrelevant.

If this was done as a joke, it would make sense. If this was done to make a point it seems disingenuous.

In formal logic, an irrelevant statement is a non-sequitur?

In my opinion it is good to recognize misleading statements. To discern a person’s intent can be more difficult. Were they attempting a joke? Attempting dishonesty? Trying to defend a position and grasping at anything to do so? Attempting to say something without actually saying anything?

People are complicated. And while it is good to recognize misleading statements, it is best not to let statements on the internet live rent free in your head for too long.

Please don't worry. This is fun for me. I stated what the I think the person's intention was earlier in the thread. That's not important right now.

It sounds like you're saying it would be good to reject misleading statements. Do I understand correctly? Don't let misleading statements live rent free = it is good to reject those misleading statements? Evict those unruly uncooperative tenants.

 

[dybmh]

If this was done as a joke, it would make sense.

Were they attempting a joke?

All the Jews I know are Atheists AND I don't know any Jews IS ridiculous, isn't it? That's the reason it could be a joke?

 

[lewisnotmiller]

Hopefully this is a simple question. Please answer the poll.

Yes or No? Does "All I know are ..." = "I don't know any ..."

Examples:

"All I know are dogs" = "I don't know any dogs" ??
"All I know are cats" = "I don't know any cats" ??
"All I know are green-martians" = "I don't know any green-martians" ??

Thank you,

I'm not reading through that whole thread, but that's not exactly what was said, at least initially. Quoting you below...

You said "All the Jews [ plural ] I know are ..." which is much different than "the only Jew I know is ..."

No, it's not. It's potentially misleading, but in a technical sense it's true. The addition of the letter 's' to form the the word 'Jews' indicates they are talking about an entire collection, not that there is a plurality. Of course a collection commonly has a plurality, but both are valid justifications for use of 'Jews' rather than 'Jew'.

And what you've put in your OP in this thread is different again.

 

[lewisnotmiller]

Humans are notoriously bad at logic. And it doesn't help that those who are not make fun of those who are. (I'm guilty, also.)
This special case can lead to side effects in programming and has been used to obfuscate code.
When you have an AND construct both statements must evaluate to true. Most C compilers therefore optimize code so that the second statement is never tested when the first is false. The side effect comes in when one of the statements is a function call. In theory AND statements are commutative, i.e. the sequence doesn't play a role but the optimization undermines that.
The author of the bad joke he played on @dybmh used this also. If he had constructed his statement like I separated them (I don't know any Jews AND all the Jews I know are atheists.) it would have been clear from the start that the second AND clause was irrelevant as the first already computed to 0.

The fact that this made sense to me indicates I've spent too much of my life in the software industry and hack programming...lol

 

[mikkel_the_dane]

Thinking logically is useful for dissecting claims. Thus is useful

Now for actually texts on logic, you have to learn formal logic.
For debates learn to spot the fallacies and the big one, free floating moral evaluations/ought to claims.

 

[Heyo]

The AND switches to an OR when the NOT is distributed.



"I know a Jew OR not all Jews KNOWN are atheists"

It's always true.



If someone knows exactly one Jew of any sort, then "I know a Jew" is true. The inclusive OR renders the entire statement true.

If someone knows no Jews, then "not all Jews KNOWN are atheists" is true. The inclusive OR renders the entire statement true.

It's always true. and BTW I think when the NOT is distributed the "ALL" becomes "ANY". But it doesn't really matter.

Man, did I mess this up. It's been a while.

You are right, AND is switched to OR and "all" to "some" (or any).

But that still doesn't make it a tautology. There is still the possible case that no Jews are atheists and I don't know a Jew.
But that's even more confusing than the original now.

 

[dybmh]

I'm not reading through that whole thread, but that's not exactly what was said, at least initially. Quoting you below...



No, it's not. It's potentially misleading, but in a technical sense it's true. The addition of the letter 's' to form the the word 'Jews' indicates they are talking about an entire collection, not that there is a plurality. Of course a collection commonly has a plurality, but both are valid justifications for use of 'Jews' rather than 'Jew'.

And what you've put in your OP in this thread is different again.

OK. Noted.

How about just a simple yes/no question. Feel free to elaborate if you wish. But I'm curious.

Is it ridiculous to say "All the Jews I know are atheists AND I don't know any Jews"?

 

[dybmh]

Man, did I mess this up. It's been a while.

You are right, AND is switched to OR and "all" to "some" (or any).

But that still doesn't make it a tautology. There is still the possible case that no Jews are atheists and I don't know a Jew.
But that's even more confusing than the original now.

No problem, i appreciate working it out. And yes, "no Jews are atheists and I don't know a Jew" specifically the way you phrased this as a negative assertion works for me. I'm not sure if it would evaluate as true in boolean logic. But, what I'm thinking is, there are multiple possible methods of trying to determine if "All the Jews I know are atheists AND I don't know any Jews" is true.

Boolean logic >>> false everytime
Law of the excluded middle ( looking for the non-existent Jews that aren't athiest and finding none ) >>> produces both true and false
Principle of explosion >>> does not match reality
Looking for contradictions >>> false everytime

If there's others I'm very interested in hearing about those methods. But from what I'm seeing, it's either false or inconclusive, but never actually true. Actually meaning that actual Jews that can possibly exist are being described. ( No one can be both atheist and theist simultaneously )

 

[Heyo]

No problem, i appreciate working it out. And yes, "no Jews are atheists and I don't know a Jew" specifically the way you phrased this as a negative assertion works for me. I'm not sure if it would evaluate as true in boolean logic. But, what I'm thinking is, there are multiple possible methods of trying to determine if "All the Jews I know are atheists AND I don't know any Jews" is true.

Boolean logic >>> false everytime
Law of the excluded middle ( looking for the non-existent Jews that aren't athiest and finding none ) >>> produces both true and false
Principle of explosion >>> does not match reality
Looking for contradictions >>> false everytime

If there's others I'm very interested in hearing about those methods. But from what I'm seeing, it's either false or inconclusive, but never actually true. Actually meaning that actual Jews that can possibly exist are being described. ( No one can be both atheist and theist simultaneously )

I think I've got it:

I described the problem of side effects in programming before. This is such a case. The two statements are not independent. "All the Jews I know are atheists" depends on the number of Jews I know. It is always true if that number is 0 and false if the number of Jews I know is not the same as atheistic Jews I know.
If I don't know any Jews, everything I say about the Jews I know is irrelevant but evaluates to true or, more exactly, not false or unknown/undefined if we don't use boolean logic.
We have to go through the set of Jews I know and evaluate the statement I make about them. As we can stop our evaluation once we find one single one to be false, we set the default to true and go through the list, breaking if we get a false. If we don't find a false one, we return the default.
The step to set the default to true is a practical programmers trick, not a logical one. In fact it is arbitrary. Strictly logical the combined statements are undecidable for an empty set and therefore not a statement.

 

[mikkel_the_dane]

I think I've got it:

I described the problem of side effects in programming before. This is such a case. The two statements are not independent. "All the Jews I know are atheists" depends on the number of Jews I know. It is always true if that number is 0 and false if the number of Jews I know is not the same as atheistic Jews I know.
If I don't know any Jews, everything I say about the Jews I know is irrelevant but evaluates to true or, more exactly, not false or unknown/undefined if we don't use boolean logic.
We have to go through the set of Jews I know and evaluate the statement I make about them. As we can stop our evaluation once we find one single one to be false, we set the default to true and go through the list, breaking if we get a false. If we don't find a false one, we return the default.
The step to set the default to true is a practical programmers trick, not a logical one. In fact it is arbitrary. Strictly logical the combined statements are undecidable for an empty set and therefore not a statement.

Thanks for the explanation. I got so far that I could spot that there were at least 2 versions of true, but that was the limit of what I could spot. Your explanation is better.

 

[dybmh]

Strictly logical the combined statements are undecidable for an empty set and therefore not a statement.

^^^WINNER^^^

It's not even a statement!

I'm proposing that it's false because the person spoke ( or typed ) something that appeared to be a statement but was infact not a statement. It's not different than claiming to "know" when in fact they "didn't know". It's not different than making a positive claim about "Jews" or anything that's known not to exist.

It's a contradiction and contradictions are false

The step to set the default to true is a practical programmers trick, not a logical one.

Yup! What's actually happening is extreme optimism. Default to true unless it's false. And that is a presumption of guilt. Guilty till proven innocent. No one agrees with that.

 

[dybmh]

It's not even a statement!

@Heyo,

In this thread and the other thread I've been calling this special case a "true-lie" because I think it captures the essence of the non-statement. It's a paradox. It's the classic liar's paradox:

"This statement is a lie"

People go around and around in circles: if it's true, then it's false. if it's false, then it's true. Nah. I propose it's false. It's a contradiction! It's not even a statement. It claims to be statement, but because it isn't, it's false. Done. It doesn't matter what words it uses, if there's an internal contradiction, that's it. The whole statement should be rejected as false.

In this specific example of the non-existing Jewish atheist, it gets confusing. Counting the non-existing Jewish non-atheists comes up empty. So, an illogical person might stop there and ignore the counter example. Counting the non-existing Jewish atheists also comes up empty. Counting non-existing things NEVER produces a sound conclusion except for one. They don't exist.

This is no different than people who claim to have proven their prophet is correct for a set of reasons, while at the same time claiming that other prophets are incorrect eventhough they are saying the same things. It's ignoring the counter-example.

I think looking for contradictions should be the first step in evaluating whether a statement is true or false. To me, this is kind of like "do no harm" morality. "Do no harm" is the very first rule. It should come before even the golden rule. "Do unto others as you would have them do to you" only works if you and the others share the same values. "Do no harm" always works.

As we have seen using formal logic doesn't always produce true/false conclusions. But rejecting contradictions always works. Can you think of a single contradiction that is true? If not, that it should be the first step when evaluating a statement. Is it even a statement? If not, it's false.

 

[Heyo]

@Heyo,

In this thread and the other thread I've been calling this special case a "true-lie" because I think it captures the essence of the non-statement. It's a paradox. It's the classic liar's paradox:

"This statement is a lie"

People go around and around in circles: if it's true, then it's false. if it's false, then it's true. Nah. I propose it's false.

Nope. That would be the same as setting the default to true. You just set the default to false.
That is a weakness in Aristotelian logic, it can't deal with unknowns. Undecidable statements just aren't statements. That is different from false.

Example:
This statement no verb.

Is it false? No, because it has no verb. But it isn't a well formulated statement (syntax error).
A special case of "not even false".

 

[dybmh]

Nope. That would be the same as setting the default to true. You just set the default to false.
That is a weakness in Aristotelian logic, it can't deal with unknowns. Undecidable statements just aren't statements. That is different from false.

Example:
This statement no verb.

Is it false? No, because it has no verb. But it isn't a well formulated statement (syntax error).
A special case of "not even false".

"This statement" is not a contradiction.

I'm not setting the default to false. I'm not saying it's false unless it's proven true. This is not pessimism. I'm saying it's false if there is an internal contradiction, and that should be evaluated first.

 

[Alien826]

I think everyone agrees that in common parlance the two statements add up to a falsehood. Mathematically though, when using formal logic can they evaluate to "true"? I think they can, but I'm no mathematician. Has @Polymath257 been involved? He usually settles things like this.

 

[dybmh]

I think everyone agrees that in common parlance the two statements add up to a falsehood. Mathematically though, when using formal logic can they evaluate to "true"? I think they can, but I'm no mathematician. Has @Polymath257 been involved? He usually settles things like this.

Yes, it can evaluate to true AND it can evaluate to false. The only way to prevent the false condition is to accept that a person can be both atheist and theist at the same time.

I'm thinking our resident expert is aware of this debate I've been having, but has chosen not to get involved.

 

[Polymath257]

I know. In another thread, someone is claiming that no "thinking person" would object to it.

Here's what they are saying:

​

It is not ridiculous to say "All the Jews I know are Atheists AND I don't know any Jews"​

This is different than the question in the OP.

In the OP, the question is whether the statements are the same. Here, the question is only whether they are consistent. Also, the statements in the OP are different than the ones here.

So, for example,
"All I know are dogs" is very different that "All dogs I know are...".
The first says you don't know anything *other* than dogs. The second says that all the dogs you know have some property.

And yes, the statements
"All dogs I know are brown" and "I don't know any dogs"
are consistent with each other. In fact, the second implies the first logically.

​

And they're trying desperately to show the so-called logic behind it. I have been arguing against it, naturally. The only argument they have brought is:

"It's obvously absolutely true. It's ridiculous to say it's false. Every thinking person agrees with me."​

So, the first, "All dogs I know are brown" can be represented by
Ax. dog(x) and known(x) ---> brown(x)
Here, I am using Ax to say 'for all x'.
The second sentence is
Ax dog(x)-->not known(x)

The second can be rewritten:
Ax not(dog(x) and known(x))

Then, the implication in the first follows from
not p ---> (p ---> q)

which is a logical truth.

 

[dybmh]

This is different than the question in the OP.

I know. The conversation advanced.

In the OP, the question is whether the statements are the same. Here, the question is only whether they are consistent. Also, the statements in the OP are different than the ones here.

The conversation advanced.

So, for example,
"All I know are dogs" is very different that "All dogs I know are...".
The first says you don't know anything *other* than dogs. The second says that all the dogs you know have some property.

Right. So if you don't know any that have that property, that is an obvious contradiction.

And yes, the statements
"All dogs I know are brown" and "I don't know any dogs"
are consistent with each other. In fact, the second implies the first logically.

In English, we read left to right, not right to left.

"All dogs I know are brown" does not imply "I don't know any dogs"

If it is read in English, it is ridiculous. Maybe if a person reads it backwards, it isn't. Let's ignore all those things though. Let's look at the proof.

So, the first, "All dogs I know are brown" can be represented by
Ax. dog(x) and known(x) ---> brown(x)
Here, I am using Ax to say 'for all x'.
The second sentence is
Ax dog(x)-->not known(x)

The second can be rewritten:
Ax not(dog(x) and known(x))

Then, the implication in the first follows from
not p ---> (p ---> q)

which is a logical truth.

First question:

​

not p ---> (p ---> q) ???​

​

What's p and what's q?​

Second question:

Ax not(dog(x) and known(x))​

​

What's known is not a dog?​

​

​

​

 

[bobhikes]

I know. In another thread, someone is claiming that no "thinking person" would object to it.

Here's what they are saying:

​

It is not ridiculous to say "All the Jews I know are Atheists AND I don't know any Jews"​

​

And they're trying desperately to show the so-called logic behind it. I have been arguing against it, naturally. The only argument they have brought is:

"It's obvously absolutely true. It's ridiculous to say it's false. Every thinking person agrees with me."​

Unfortunately your OP poll doesn't match what you are saying in this quote. "All I know are XXX" is not the same as "All the XXX I know are YYY".

If All you know are Dogs, then you can't distinguish between Humans, Pigs and Dog's, all you know is Dogs. You need to be open to teaching. All the rose's I know are flowers is a valid statement and true, that doesn't mean you can have a falsehood All the tree's I know are cars and I don't know any tree's, while a falsehood it can also be misunderstanding and the person needs to be open to teaching. If the person is not open to teaching, good luck.