Three stages

[jeremyp]

I am not concluding that it is an impossibility. I am just not accepting the positive claim that it is a possibility. Can you demonstrate the positive claim that the after life is a pissibility?

It's not a positive claim. It's merely the recognition that the evidence doesn't rule out an afterlife. If you conclude that the afterlife cannot be ruled out given the evidence we have, you logically must accept that it is a possibility.

Accepting the possibility is nothing like believing there is an afterlife.

[jeremyp]

It's bad logic.

No it isn't.

The claim that something is a possibilty is by definition a positive one.

No it isn't.

I don't know if the 'after life' is possible.

Nor do you know it is impossible based on current evidence, therefore on the basis of evidence, you must conclude it is possible.

[Nearly Sane]

It's not a positive claim. It's merely the recognition that the evidence doesn't rule out an afterlife. If you conclude that the afterlife cannot be ruled out given the evidence we have, you logically must accept that it is a possibility.

Accepting the possibility is nothing like believing there is an afterlife.

Explain how 'It is possible' is not a postive claim.

[Nearly Sane]

No it isn't.
No it isn't.

Nor do you know it is impossible based on current evidence, therefore on the basis of evidence, you must conclude it is possible.

It is possible is equivalent to stating it is not impidsible. What evidence do you have to show it is not impossible?

[Nearly Sane]

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.

So following you connecting these ideas, it would follow from your logic that were you to say that you were unable to show that something was unfalsifiable, that would mean that it was falsifiable.

[jeremyp]

Explain how 'It is possible' is not a postive claim.

It's not really a claim at all. It's merely saying "we can't rule it out".

[jeremyp]

It is possible is equivalent to stating it is not impidsible. What evidence do you have to show it is not impossible?

I cannot give you any evidence to show that it is impossible. Therefore, by definition, it is possible.

[Nearly Sane]

It's not really a claim at all. It's merely saying "we can't rule it out".

So something may indeed not be possible, but saying it is possible is not a positive claim about it?

You are also happy to say that the statement 'I do not know if it is possible or not' is equivalent to 'It is possible' here.

[Nearly Sane]

I cannot give you any evidence to show that it is impossible. Therefore, by definition, it is possible.

  even if in fact it is impossible.

'I cannot give you any evidence to show that it is unfalsifiable. Therefore, by definition, it is falsifiable'

[jeremyp]

So something may indeed not be possible, but saying it is possible is not a positive claim about it?

You are also happy to say that the statement 'I do not know if it is possible or not' is equivalent to 'It is possible' here.

Yes I am.

Obviously, I think it unlikely that there is an afterlife and if you want me to place a bet, it would be against an afterlife, but I cannot bring evidence to the table to say it is impossible, therefore I have to concede it is possible - by definition.

[Nearly Sane]

Yes I am.

Obviously, I think it unlikely that there is an afterlife and if you want me to place a bet, it would be against an afterlife, but I cannot bring evidence to the table to say it is impossible, therefore I have to concede it is possible - by definition.

So we reverse the approach, and I ask you for evidence that it is possible, and you can provide none, by this approach it means it is impossible?

[Nearly Sane]

Yes I am.

Obviously, I think it unlikely that there is an afterlife and if you want me to place a bet, it would be against an afterlife, but I cannot bring evidence to the table to say it is impossible, therefore I have to concede it is possible - by definition.

So if you ask the question 'Is this possible?', a person saying 'I don't know' and a person saying 'Yes' are making exactly equivalent statements?

[bluehillside Retd.]

NS,

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

But that the “with my current state of knowledge” is the critical a priori point here. I have no basis to assume that my current state of knowledge gives me anywhere near enough information to rule out anything – square circles and "y*&^%(^TO*G" included. The former is impossible only inasmuch as my grasp of logic tells me it is, and the latter may turn out to have meaning even though I have no way of discerning what it is.

Absent omniscience, on what ground then could argue that either of them (or anything else) isn’t possible?     

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

But if I cannot say that anything is impossible, aren’t I also saying necessarily that anything is therefore possible (even if that “thing” is incoherent to me)?

[Nearly Sane]

NS,

But that the “with my current state of knowledge” is the a priori point here. I have no basis to assume that my current state of knowledge gives me anywhere near enough information to rule out anything – square circles and "y*&^%(^TO*G" included. The former is impossible only inasmuch as my grasp of logic tells me it is, and the latter may turn out to have meaning even though I have no way of discerning what it is.

Absent omniscience, on what ground then could argue that either of them (or anything else) isn’t possible?     

But if I cannot say that anything is impossible, aren’t I also saying necessarily that anything is therefore possible (even if that “thing” is incoherent to me)?

Saying 'I don't know if something is possible' is not ruling anything out.

Saying something is possible is ruling out that it is impossible.

[bluehillside Retd.]

NS,

Saying 'I don't know if something is possible' is not ruling anything out.

Yes.

Saying something is possible is ruling out that it is impossible.

In epistemological terms, yes. I can’t rule out that anything is impossible even when the proposed "thing" is undefined or incoherent to me.     

[Nearly Sane]

NS,

Yes.

In epistemological terms, yes. I can’t rule out that anything is impossible even when the proposed "thing" is undefined or incoherent to me.     

I'm confused by your last paragraph. Prof D is saying that because we can't say 'after life' is impossible, therefore it is possible. And yet you've agreed with me saying
'Saying something is possible is ruling out that it is impossible'. So that would mean you think Prof D has a logical paradox in his position.

[Maeght]

I previously said that I'd accept that an after life is possible, but I don't actually know if it is possible or not really. How you phrase that to everyone's satisfaction I don't really know either. Maybe saying I accept it might be possible?

[ProfessorDavey]

I previously said that I'd accept that an after life is possible, but I don't actually know if it is possible or not really. How you phrase that to everyone's satisfaction I don't really know either. Maybe saying I accept it might be possible?

I think something is either possible (probability >0) or impossible (probability =0). So unless a claim is confirmed to be impossible, i.e. falsified, then it should be considered possible.

Now we also have to factor in the level of knowledge - so we make a judgment on the current available evidence. So a claim may be considered possible currently, but if knowledge increases to the extent that the claim is clearly falsified we would conclude that on the basis of the new evidence that the claim isn't possible.

But I think the notion of 'I don't know if it is possible' seems to be muddying the waters - if you don't know that it is impossible then surely it must be considered possible based on the knowledge available at the time.

[BeRational]

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!

Agreed. But rain has been demonstrated, and so has the Pacific Ocean. So this is a possibility.

I think where I disagree, is when you accept something as possible simply because you do not know that it is impossible, and I don't think that is the correct approach.

What if someone posited several claims some of which would make previous claims impossible. If you accept them all as possible, then you know for sure that you must be accepting a claim that is countered by another.

[BeRational]

It's not really a claim at all. It's merely saying "we can't rule it out".

True, but you also cannot rule it in either.

Saying something is possible or impossible is a claim that has a burden.

Simply saying we don't know does not.

[ProfessorDavey]

True, but you also cannot rule it in either.

But saying a claim is possible is neither ruling it in nor ruling it out - unless it is 'certain', then it is the equivalent of saying that we don't know whether the claim is true or not.

Saying something is possible or impossible is a claim that has a burden.

Not really - saying something is impossible is a positive claim that the original claim is false. Saying it is possible isn't the same - effectively all it means is that we cannot conclude that it is impossible - it is no more a positive claim than saying you don't believe in something.

Simply saying we don't know does not.

But it is effectively the same thing - the question isn't 'do I know if it is possible' - the claim is either true or not true - if it is not true then it is impossible, if the claim is true that doesn't make it possible (which retains an element of doubt) - nope it makes it certain.

If we don't know whether a claim is true or not then we cannot conclude that the probability of the claim being true is either 0 (impossible/falsified) or 1 (certain/demonstrated). In which case probability is >0 but <1, and that surely must be described as possible (but neither impossible/false nor certain/true).

[Gordon]

But to say something is "not impossible" surely leaves open the option of it being "possible".

If the "not impossible" is a proposal that is grounded on what is currently in place: say that the storage potential of batteries for electric cars could be increased by 20% over the next 5 years due to technical advances, then that proposal is "not impossible" since it is informed speculation based on what is extant, even if it turned out to be wrong.

However if "not impossible" is the response to a claim like 'an after life' that has no grounding in logic, reason or credible evidence then surely the correct response is say that without any grounding in logic, reason or credible evidence then the claim is currently no more than meaningless white noise, and that no assessment of it's 'possibility' can therefore be made. In essence, the 'impossible/possible' categorisation can't even be considered since it can't apply as things stand.

[BeRational]

But to say something is "not impossible" surely leaves open the option of it being "possible".

If the "not impossible" is a proposal that is grounded on what is currently in place: say that the storage potential of batteries for electric cars could be increased by 20% over the next 5 years due to technical advances, then that proposal is "not impossible" since it is informed speculation based on what is extant, even if it turned out to be wrong.

However if "not impossible" is the response to a claim like 'an after life' that has no grounding in logic, reason or credible evidence then surely the correct response is say that without any grounding in logic, reason or credile evidbence then the claim is currently no more than meaningless white noise, and that no assessment of it's 'possibility' can therefore be made. In essence, the 'impossible/possible' categorisation can't even be considered since it can't apply as things stand.

You put it much better than me, and yes I completely agree.

[jeremyp]

So we reverse the approach, and I ask you for evidence that it is possible, and you can provide none, by this approach it means it is impossible?

No, because that would be an argument from personal incredulity.

[Nearly Sane]

No, because that would be an argument from personal incredulity.

So the reverse of that is simply personal credulity, and equally worthless.