True AND false?

[sven]

If you cannot know for certain that something is true nor false, should you accept both as possibilites? Meaning, should you believe it to be both true and false if it's impossible to know whether something is or isn't? :)

[justinglives]

Yes.

[sven]

Yes.

Why?

[ArsenicCatNip]

What exactly would be impossible to ever know?
inb4 this turns into a stupid God debate. How exciting

[huginnmuninn]

Schrodinger's cat... that's why

[Gigablue]

I don't think so. You should say that both are possible, but not known. You should also apply Occam's razor to find the more likely possibility, but remain open to new evidence. There is no reason to say it is both true and false.

Schrodinger's cat... that's why

Schrödinger's cat applies to cry small particles, and says that prior to observation, it exists in both of its possible states. It can't apply to a statement.

[Mortal Coil]

You should accept that you do not know, and say that it is neither true nor false.

[huginnmuninn]

Schrödinger's cat applies to cry small particles, and says that prior to observation, it exists in both of its possible states. It can't apply to a statement.

I should really start writing more in my posts...

You can accept that a situation or a problem is both true and false until you find evidence that either proves or disproves a scenario. My use of Schrödinger's cat meant that in the same way that you can accept that the cat is both alive and dead, you can accept that something is both true and false.

[Magical]

I should really start writing more in my posts...

You can accept that a situation or a problem is both true and false until you find evidence that either proves or disproves a scenario. My use of Schrödinger's cat meant that in the same way that you can accept that the cat is both alive and dead, you can accept that something is both true and false.

But the cat is NOT both alive and dead in the same way a statement can be true and false (it can't). Something checks, and it becomes either dead or alive. It doesn't work like that for the statement.
Anyway, the Schrödinger's cat thought experiment was an attempt to point out the flaws of the Copenhagen interpretation of quantum mechanics.
http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat
You can not accept that something is true and false. You can accept that it is unknown, but not true and false.

[TigerBoy]

If you cannot know for certain that something is true nor false, should you accept both as possibilites? Meaning, should you believe it to be both true and false if it's impossible to know whether something is or isn't? :)

Whether or not you know which one it is, the thing could well be something that has to be either 'true OR false', but depending on what you are referring to and the statement you are making it may not be useful to try to describe it in terms of 'truth' in the first place. So your knowledge about the context is important - if you don't know much about it obviously you are less likely to make sensible statements.

Its perfectly possible to make a statement that accepts both possibilities of 'true' and 'false', and is a routine thing for formal logic to express it. The overall statement is that "its either this, or its that".

In terms of the idea of possibilities, some logic systems are multi-valued and allow for "true", "false" and "unknown", and others allow you to assign a probability value of how likely to be true something is, allowing to quantify how likely something is. "its 20% likely its this".

If you have two things where only one can be true, your two probabilities have to add up to 100% likely in any statement, eg "Its 20% likely its A and 80% likely its B"

That doesn't mean you 'believe' both are true at the same time, you just believe that the answer has to be one of those things.

Having said that there are various logic systems that attempt to model how plausible a belief or a conclusion is (based around the "evidential reasoning" approach, or certain auto-epistemic logics), so in that sense you could have two or more potential beliefs even while there may be a degree of conflict between the details of each, all while you don't have enough facts to 'know' which it is. As facts come along and reduce the possibilities you can then apply a mechanism called 'belief revision' to reform your beliefs or discount them.
(This latter point being where the discussion in 'are you a believer' has become a bit crazy :) )

That's basically where I've got to on the basis of certain recent discussions, anyway ;-) Hope it helps.

[dontfiguremeout]

Hmmm I would say then don't choose any at the moment. If you don't know exactly, then you really don't know at all. Not choosing if it's true or false, then gives me the freedom of not being right or wrong at all! Plus I would wait to bud into thinking true or false when I get enough info that it's clearly one or the other, not a mixture of both. This is just my opinion though.

[thesurferdude]

What's going on here?

If you don't know if something is true or false first you should try to find out.

Should you ever accept something simotaniously as true and false? No, Never.

If you cant know for certain often thats okay. you can still have ideas and hints.

[TigerBoy]

Should you ever accept something simotaniously as true and false? No, Never.

Then how about the following statement:

"This statement is not true".

Then again you have subjectivity. Ask someone if a girl is beautiful - one person may say 'yes' the other 'no'. If I am blind, I could consider that both people are right. (Subjective logic is a formal logic system that deals with uncertainty and belief ownership and multiple conflicting beliefs).

As I said earlier, if knowledge is limited it may not even be meaningful to try to form a statement in terms of something being 'true or false', and if you try you may end up with an unsatisfactory statement that permits both possibilities or neither.

[Lost in the Echo]

Yes, being open minded towards others opinions is ok, but it's fine to have your own opinion. We're all different, so having your opinion is fine, just have respect for somebody else's opinion.

[thesurferdude]

Then how about the following statement:

"This statement is not true".

Then again you have subjectivity. Ask someone if a girl is beautiful - one person may say 'yes' the other 'no'. If I am blind, I could consider that both people are right. (Subjective logic is a formal logic system that deals with uncertainty and belief ownership and multiple conflicting beliefs).

As I said earlier, if knowledge is limited it may not even be meaningful to try to form a statement in terms of something being 'true or false', and if you try you may end up with an unsatisfactory statement that permits both possibilities or neither.

Thank's for the criticism you really made me think. How would you feel if I maintained my statement when absolute's apply. And I'm wrong on counts of subjectivity.

[TigerBoy]

Thank's for the criticism you really made me think. How would you feel if I maintained my statement when absolute's apply. And I'm wrong on counts of subjectivity.

Ouch sorry wasn't meant to be criticism just food for thought really.

To answer your question, my view is that although there are cases where it isn't that simple or clear, there are also plenty of cases where you are absolutely correct that it would be daft to hold things as 'true AND false' and that is indeed the normal case in traditional propositional logic.

[thesurferdude]

Ouch sorry wasn't meant to be criticism just food for thought really.

To answer your question, my view is that although there are cases where it isn't that simple or clear, there are also plenty of cases where you are absolutely correct that it would be daft to hold things as 'true AND false' and that is indeed the normal case in traditional propositional logic.

I wasn't offended. You critiqued my statement. Thats a good thing.

So to clarify if its not clear; we just say we don't know. We don't claim its wright wrong or both. And if we know then its simple we just know.

For example if I ask you if you brushed your teeth today your answer is either yes or no never both. But if you don't remember then its unknown.

[TigerBoy]

I wasn't offended. You critiqued my statement. Thats a good thing.

So to clarify if its not clear; we just say we don't know. We don't claim its wright wrong or both. And if we know then its simple we just know.

In practice its often more sensible to say that but you don't have to stop there. You can apply scientific method to a real world problem if you are in a position to test a hypothesis and advance your knowledge that way.
In traditional propositional logic its required that you don't claim things are both true AND false, but as in the case of subjectivity it may be useful to consider both possibilities as 'true' so other schemes exist to handle such things.


For example if I ask you if you brushed your teeth today your answer is either yes or no never both. But if you don't remember then its unknown.
Yep, or instead of 'unknown' you might want to assign a probability value based on your knowledge of how regularly I brush my teeth if that is useful.
But knowledge about the subject you are making statements about is vital to be able to use 'true or false' answers to draw conclusions. If you don't know enough about my morning routine the question may not be meaningful - if I had some special mouthwash that didn't require brushing, then my answer "false" may lead you to think I'm a bit skanky. If you knew about the existance of this special mouthwash, you may decide what you really needed to ask was "have you cleaned your teeth".

[thesurferdude]

In practice its often more sensible to say that but you don't have to stop there. You can apply scientific method to a real world problem if you are in a position to test a hypothesis and advance your knowledge that way.
In traditional propositional logic its required that you don't claim things are both true AND false, but as in the case of subjectivity it may be useful to consider both possibilities as 'true' so other schemes exist to handle such things.


Yep, or instead of 'unknown' you might want to assign a probability value based on your knowledge of how regularly I brush my teeth if that is useful.
But knowledge about the subject you are making statements about is vital to be able to use 'true or false' answers to draw conclusions. If you don't know enough about my morning routine the question may not be meaningful - if I had some special mouthwash that didn't require brushing, then my answer "false" may lead you to think I'm a bit skanky. If you knew about the existance of this special mouthwash, you may decide what you really needed to ask was "have you cleaned your teeth".

I agree.