Three stages

[ProfessorDavey]

You're very confused. There is a significant difference between claiming something is a possibility, and that it exists as your second para seems to substitute as the claim.

I'm not confused at all - all along I've been clear about the difference between considering a claim to exist or be true and whether a claim is possible - however implausible.

To state that something is a possibility means you must demonstrate that the possibility is not 0.

But you are into Popper territory - the only way we take something out of possibility is to demonstrate that the probability is either 0 (impossible) or 1 (certain) - unless either of those two positive claims have been demonstrated then we retain the negative claim that it is possible - i.e. probability is >0 but <1.

So for my dice example - while we lack knowledge (what is on one side is unknown) then we cannot say rolling a 7 is impossible, so it remains a possibility (the hidden side could be a 7). If we gain additional knowledge - i.e the hidden side is revealed to a 6, then the notion that rolling a 7 is possible falls away as it has been demonstrated to be impossible (probability 0).

[BeRational]

Not really - something is either possible or impossible - there are no other categories. Impossible means probability = 0. Possible simply means not impossible, i.e. probability >0. So unless we have demonstrated something to be impossible we must conclude (in the absence of confirmatory evidence) that it is possible because we cannot reasonable conclude that the probability is definitely 0.

I accept this it is either possible or not possible, as they are logical opposites. But as to what the answer actually is, I do not know. I cannot accept either.

My example would be, my lawn has either an odd number of blades of grass or an even number. I accept it HAS to be one or the other, but I do not accept the claim that the number is odd, nor do I accept that is is even. I would have to count them, then I would know.

[Nearly Sane]

I'm not confused at all - all along I've been clear about the difference between considering a claim to exist or be true and whether a claim is possible - however implausible.
But you are into Popper territory - the only way we take something out of possibility is to demonstrate that the probability is either 0 (impossible) or 1 (certain) - unless either of those two positive claims have been demonstrated then we retain the negative claim that it is possible - i.e. probability is >0 but <1.

So for my dice example - while we lack knowledge (what is on one side is unknown) then we cannot say rolling a 7 is impossible, so it remains a possibility. If we gain additional knowledge - i.e the hidden side is revealed to a 6, then the notion that rolling a 7 is possible falls away as it has been demonstrated to be impossible (probability 0).

Except that in the case of the die you know the 7 is possible. It can be demonstrated because of your knowledge of dice. What equivalent knowledge do you have of 'after life'?

[ProfessorDavey]

I accept this it is either possible or not possible, as they are logical opposites. But as to what the answer actually is, I do not know. I cannot accept either.

My example would be, my lawn has either an odd number of blades of grass or an even number. I accept it HAS to be one or the other, but I do not accept the claim that the number is odd, nor do I accept that is is even. I would have to count them, then I would know.

Absolutely correct - but until (or unless) we have definitely demonstrated the number of grass blades to be either odd or even both remain a possibility. If we count 10,000,000 then we can conclude that odd is impossible and therefore the possibility falls away.

But in your example we'd start on the basis of probability of around 0.5, until we have a definitive answer. With the claims we are discussing we might be considering that the probability is absolutely tiny, but we cannot conclude that it is definitely 0.

[Nearly Sane]

I accept this it is either possible or not possible, as they are logical opposites. But as to what the answer actually is, I do not know. I cannot accept either.

My example would be, my lawn has either an odd number of blades of grass or an even number. I accept it HAS to be one or the other, but I do not accept the claim that the number is odd, nor do I accept that is is even. I would have to count them, then I would know.

Not sure that works here as you accept because of the nature of the claim and your knowledge of numbers both the possibilities that there are even or odd numbers of blades of grass.

I would suggest that in the case of 'after life' we have no such equivalent knowledge, and that's what allows the position that it makes no sense to claim it is a possibility

[BeRational]

Absolutely correct - but until (or unless) we have definitely demonstrated the number of grass blades to be either odd or even both remain a possibility. If we count 10,000,000 then we can conclude that odd is impossible and therefore the possibility falls away.

But in your example we'd start on the basis of probability of around 0.5, until we have a definitive answer. With the claims we are discussing we might be considering that the probability is absolutely tiny, but we cannot conclude that it is definitely 0.

I slightly disagree as in my example the possibility of the number being odd or even HAS been demonstrated, because we know how numbers work, and we know what a lawn is.

If I said my lawn also contained SDFds64534!!". Would you think it possible that it did?

I would not accept this claim until it was defined, and demonstrated that it could be on my lawn.

Simply speaking I do not say everything is possible. How can I, I do not know what is possible or impossible. Whoever makes the claim that something is possible or not, has the burden.

[ProfessorDavey]

Except that in the case of the die you know the 7 is possible.

No you don't if all the visible sides aren't 7 but there is a hidden side that could be a 7 or might not be a 7. Only once we know that the other side isn't a 7 can we conclude that rolling a 7 is impossible and possibility falls away.

It can be demonstrated because of your knowledge of dice. What equivalent knowledge do you have of 'after life'?

But the issue is our lack of knowledge - and that is the same for an after life. It may be 'unknowable' in which case we can never conclude absolutely that the probability is 0 (i.e. impossible) and therefore that it would always remain possible, however implausible and however much we do not accept it as a claim.

It would be a bit like asking about rolling a 7, but never being allowed to know what the hidden side actually shows.

[Nearly Sane]

No you don't if all the visible sides aren't 7 but there is a hidden side that could be a 7 or might not be a 7. Only once we know that the other side isn't a 7 can we conclude that rolling a 7 is impossible and possibility falls away.
But the issue is our lack of knowledge - and that is the same for an after life. It may be 'unknowable' in which case we can never conclude absolutely that the probability is 0 (i.e. impossible) and therefore that it would always remain possible, however implausible and however much we do not accept it as a claim.

It would be a bit like asking about rolling a 7, but never being allowed to know what the hidden side actually shows.

But you have knowledge of numbers and dice that means you can conclude it is a possibility. You've merely provided another version of BR's blades of grass, which you quite rightly argued doesn't work'.

[Nearly Sane]

I slightly disagree as in my example the possibility of the number being odd or even HAS been demonstrated, because we know how numbers work, and we know what a lawn is.

If I said my lawn also contained SDFds64534!!". Would you think it possible that it did?

I would not accept this claim until it was defined, and demonstrated that it could be on my lawn.

Simply speaking I do not say everything is possible. How can I, I do not know what is possible or impossible. Whoever makes the claim that something is possible or not, has the burden.

I think that's a better approach. It's not clear to me that 'after life', or indeed god, have logically coherent definitions.

I cannot say that SDFds64534!!, whatever you mean by that, is impossible but that does not mean that I think, as Prof D's approach is, that it is possible. I am an SDFds64534!! noncognitivist.

[BeRational]

Not sure that works here as you accept because of the nature of the claim and your knowledge of numbers both the possibilities that there are even or odd numbers of blades of grass.

I would suggest that in the case of 'after life' we have no such equivalent knowledge, and that's what allows the position that it makes no sense to claim it is a possibility

Completely agree. We do not know if it is possible so we cannot accept it.

For example, it might be that it IS possible for life to continue after death, just that it never does in reality.

[ProfessorDavey]

Completely agree. We do not know if it is possible so we cannot accept it.

I don't disagree, but firstly for something to be possible all that means is that is isn't impossible and for it to be demonstrably to be impossible we'd need to have been able to definitely falsified the claim. So to my mind anything that hasn't been definitely demonstrated (i.e. the claim has been proven to be true) nor definitely falsified (i.e. the claim had been proved to be impossible) then it sits in the 'possible' category, however implausible. All possible mean is 'not demonstrated' and 'not falsified'.

But secondly, and more importantly, just because a claim is possible (i.e. not definitely demonstrated, nor falsified) doesn't mean we should accept it. This is where the distinction between believe and knowledge lies. I'm an atheist as I do not believe the claims that god exists. But I am agnostic on knowledge - as the existence of god has neither been definitely demonstrated, nor definitively falsified god's existence remains possible, however implausible.

For example, it might be that it IS possible for life to continue after death, just that it never does in reality.

The surely that would remain as a possibility - and this is where we have major challenges with supernatural claims that aren't able to either demonstrated nor falsified. So although a supernatural claim may always remain a possibility (as if has not and perhaps cannot be either demonstrated nor falsified) in terms of the real world the notion that it remains a possibility becomes completely pointless as it has no bearing on reality. Russell's teapot and all that.

[Nearly Sane]

I don't disagree, but firstly for something to be possible all that means is that is isn't impossible ...

Not being able to show something is impossible is not equivalent to it not being  impossible - as you have used it here.

Edited to make sense.

[ProfessorDavey]

If I said my lawn also contained SDFds64534!!". Would you think it possible that it did?

I would not accept this claim until it was defined, and demonstrated that it could be on my lawn.

Nor would I accept the claim, but that doesn't mean it isn't possible. And until a claim is either definitely demonstrated or definitively falsified it remains a possibility.

Indeed the lack of definition doesn't help, because it counters the ability to demonstrate or falsify and renders the claim still possible (albeit potentially a rather pointless claim).

So while SDFds64534 remains completely undefined we remain firmly in the territory of possible - however it it is finally defined as a well known weed variety, water, or my pet dog, then we might firmly accept the claim.

Alternatively (and this is where the supernatural claims come in) it could be defined like Russell's teapot or Sagan's garage dragon - an supernatural entirely that isn't susceptible to detection by any objective and material processes. In that case, well it would still remain possible, but we'd reject the actual claim on the basis of lack of evidence and also that we could never tell the difference between a lawn with SDFds64534 and one without.

[Nearly Sane]

Nor would I accept the claim, but that doesn't mean it isn't possible. And until a claim is either definitely demonstrated or definitively falsified it remains a possibility.

Indeed the lack of definition doesn't help, because it counters the ability to demonstrate or falsify and renders the claim still possible (albeit potentially a rather pointless claim).

So while SDFds64534 remains completely undefined we remain firmly in the territory of possible - however it it is finally defined as a well known weed variety, water, or my pet dog, then we might firmly accept the claim.

Alternatively (and this is where the supernatural claims come in) it could be defined like Russell's teapot or Sagan's garage dragon - an supernatural entirely that isn't susceptible to detection by any objective and material processes. In that case, well it would still remain possible, but we'd reject the actual claim on the basis of lack of evidence and also that we could never tell the difference between a lawn with SDFds64534 and one without.

If you cannot define something coherently, talking about possibility or impossibility is in the not even wrong territory.

[ProfessorDavey]

If you cannot define something coherently, talking about possibility or impossibility is in the not even wrong territory.

It may be entirely pointless, but that is a different matter to whether the claim is possible or not. But in pure logic terms if a claim isn't clearly defined then it is far harder to ether demonstrate or falsify and therefore will continue to remain in the territory of possible.

That's why science is based on tightly defined claims (we call them hypotheses) that are amenable to testing to be demonstrate or falsified. That said, even in the world of objective science, what we are really doing is working in the territory of ranges of probabilities. Typically we accept a 'positive' result if the likelihood of the realist happening by chance is less than 5% (some studies may have more stringent criteria), but we are never really able to say that the probability is 0, i.e. it is impossible that it could happen by chance.

[Nearly Sane]

It may be entirely pointless, but that is a different matter to whether the claim is possible or not. But in pure logic terms if a claim isn't clearly defined then it is far harder to ether demonstrate or falsify and therefore will continue to remain in the territory of possible.

That's why science is based on tightly defined claims (we call them hypotheses) that are amenable to testing to be demonstrate or falsified. That said, even in the world of objective science, what we are really doing is working in the territory of ranges of probabilities. Typically we accept a 'positive' result if the likelihood of the realist happening by chance is less than 5% (some studies may have more stringent criteria), but we are never really able to say that the probability is 0, i.e. it is impossible that it could happen by chance.

So is it possible that green ideas sleep furiously?

[ProfessorDavey]

So is it possible that green ideas sleep furiously?

Yes if the claim is completely undefined (e.g. that green ideas is in fact a person who has a disturbed sleep disorder that makes him or her thrash around at night that his or her partner describes as 'sleeping furiously'), albeit it is a completely pointless claim without proper definition and so is irrelevant for consideration or action - see Sagan's dragon.

[bluehillside Retd.]

NS,

I think that's a better approach. It's not clear to me that 'after life', or indeed god, have logically coherent definitions.

I cannot say that SDFds64534!!, whatever you mean by that, is impossible but that does not mean that I think, as Prof D's approach is, that it is possible. I am an SDFds64534!! noncognitivist.

Isn’t the point here the “possible/impossible” are expressions of states of knowledge, but not necessarily descriptions of reality too? Thus any-thing is possible even though I have no idea what that “thing” might be, even if the framing of the proposition isn’t coherent to me either.

If for all I know I’m just a character in a super-advanced version of The Sims then maybe my algorithm is just programmed to tell me that square circles are impossible, and maybe too “ih9&)^&” has a meaning even though I have no idea what it might be and so, conceptually at least, could also be possible.   

[bluehillside Retd.]

NS,

So is it possible that green ideas sleep furiously?

Yes, at least conceptually, because for all I know that sentence has meaning beyond my ability to discern what it is.

[Nearly Sane]

Yes if the claim is completely undefined (e.g. that green ideas is in fact a person who has a disturbed sleep disorder that makes him or her thrash around at night that his or her partner describes as 'sleeping furiously'), albeit it is a completely pointless claim without proper definition and so is irrelevant for consideration or action - see Sagan's dragon.

Sagan's dragon is a point about unfalsifiability, not about logical incoherence. Good to know ypu have no understanding of Sagan, as well as Chomsky.

[Nearly Sane]

NS,

Yes, at least conceptually, because for all I know that sentence has meaning beyond my ability to discern what it is.

But can you with your current state of kniwledge say that it is possible?

ETA - your formulation seems to me to be a version of you being unable to say that it is impossible.

[ProfessorDavey]

Sagan's dragon is a point about unfalsifiability, not about logical incoherence.

The points are completely linked - if something is unfalsifiable (and presumable also not amenable to be definitely demonstrated, as per Sagan's example) it forever will sit in the category of possible, but that we would neither accept the claim nor make any adjustment to our life on the basis of the claim.

[BeRational]

The points are completely linked - if something is unfalsifiable (and presumable also not amenable to be definitely demonstrated, as per Sagan's example) it forever will sit in the category of possible, but that we would neither accept the claim nor make any adjustment to our life on the basis of the claim.

I disagree that it falls into the possible camp. It falls into the unkown camp.

What if you accept something as possible (because you have insufficient information) when in reality it is impossible.

There is no need to accept something as possible, until it can be demonstrated that it is indeed possible.

[ProfessorDavey]

But can you with your current state of kniwledge say that it is possible?

ETA - your formulation seems to me to be a version of you being unable to say that it is impossible.

BHS seems to be spot on, if I am reading his post correctly.

Something remains possible until or unless it has been demonstrate definitely (then it becomes certain) or falsified (demonstrated to be impossible, i.e. probability of the claim being correct is 0). If we lack knowledge we will find it that much harder to either demonstrate definitely or definitely falsify the claim. So lack of knowledge makes it far more likely that a claim is possible, rather than impossible (or certain, which is really a subset of possible where probability is 1).

[ProfessorDavey]

I disagree that it falls into the possible camp. It falls into the unkown camp.

But it isn't either or - plenty of things are unknown but also possible. If I asked you whether it is raining in the middle of the Pacific Ocean right now, you may not know (you lack knowledge) but you'd accept it to be perfectly possible (i.e. not impossible). On the other hand if I asked the same question about a point somewhere between our galaxy and another galaxy ... well, that might produce a different response!