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Author Topic:   The Antecedent Probability Principle, the Proportional Principle & Carl Sagan
Tangle
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Posts: 9489
From: UK
Joined: 10-07-2011
Member Rating: 4.9


Message 1 of 72 (657826)
03-30-2012 2:41 PM


Or why we can never believe in miracles.
If you tell me that there is a statue in a church of the Virgin Mary it is rational of me to accept your assertion because my life experience tells me that this is quite possible - statues often hang out in churches. If you have no history of lying to me randomly about everyday events and there is no other reason to suspect that you could be mistaken there is no logical reason to doubt you.
This is the Antecedent Probability Principle. I accept what you tell me because it lies within what I know to be probable.
If, however, you also say "and it's hovering 6 feet off the floor" I then have cause to doubt. I know from experience that statues don't hover and that there is a greater likely hood of your assertion being false - for whatever reason. If I am to behave rationally I must assume you are mistaken.
In order for me to believe you I then need far more evidence than normal. What is happening here is that I proportion my belief in what you have told me in relation to the net evidence for it. The more rationally unlikely the event, the more unlikely it is to be true and the more evidence is therefore needed for it. This is the philosopher’s version of Carl Sagan’s argument that extraordinary claims need extraordinary evidence.
If someone chooses to accept weak evidence for extraordinary events above their known experience of the physical world they are therefore thinking irrationally.
However, it may be that the hovering statue is still hovering, in which case you can go and test it so that the standard of evidence matches the scale of its improbability. If after doing some simple tests yourself it would then be rational to believe that some miraculous intervention is occurring.
But note, while it may well be rational to think that way, it may still be an error as it may be that your understanding of the phenomena is just incomplete.
To give an old example, a solar eclipse would seem miraculous if you hadn't lived in a culture that has the science to understand it.
Also, the fact that you have done some tests that convinces YOU, it does not mean that when you tell someone else that it is rational for THEM to believe you. They may take note of what you say, take your tests into consideration but still reject it because they rightly need more objective analysis if they cannot witness the event themselves.
And so on.
The logical conclusion of this argument is that miracles cannot exist. This is because the more extraordinary the event, the less credible it must be, and as a miracle defies a natural law - which is impossible - they therefore cannot exist.
I'm sure this begs the question. Maybe someone who has properly studied this can take the argument further?

Life, don't talk to me about life - Marvin the Paranoid Android

Replies to this message:
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AdminModulous
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Message 2 of 72 (657828)
03-31-2012 5:05 AM


Thread Copied from Proposed New Topics Forum

  
Dr Jack
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(2)
Message 3 of 72 (657829)
03-31-2012 6:04 AM
Reply to: Message 1 by Tangle
03-30-2012 2:41 PM


Actually, you should be concluding that it cannot be rational to believe in miracles, not that they can't exist. Hume makes a similar argument.
In my view, the flaw is preponderance of evidence, as your gather data there comes a point were clinging to your existing beliefs in the face of the evidence becomes irrational. It's just hard to reach that point.

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NoNukes
Inactive Member


Message 4 of 72 (657842)
03-31-2012 9:01 AM
Reply to: Message 1 by Tangle
03-30-2012 2:41 PM


The logical conclusion of this argument is that miracles cannot exist. This is because the more extraordinary the event, the less credible it must be, and as a miracle defies a natural law - which is impossible - they therefore cannot exist.
I don't think you've quite made your point. I'm sure that there are things that are true for which we currently have no evidence.
At best you've demonstrated that it is unlikely that we will ever have proof that a miracle has occurred.
And I'm not convinced that it is irrational to accept things without proof or strong evidence? What evidence/proof did Einstein have when he was working on general relativity? My understanding is that the missing science that Einstein perceived was more a product of aesthetics than of any disagreement with experiment. Was it rational for Albert to spend a decade working on general relativity under those circumstances?

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison

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nwr
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Posts: 6408
From: Geneva, Illinois
Joined: 08-08-2005
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(2)
Message 5 of 72 (657850)
03-31-2012 11:10 AM
Reply to: Message 1 by Tangle
03-30-2012 2:41 PM


Tangle writes:
The logical conclusion of this argument is that miracles cannot exist.
No. The rational conclusion is that one should be highly skeptical of claims of miracles.

Jesus was a liberal hippie

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Jon
Inactive Member


Message 6 of 72 (657851)
03-31-2012 11:18 AM
Reply to: Message 1 by Tangle
03-30-2012 2:41 PM


Irrational by Definition
The logical conclusion of this argument is that miracles cannot exist. This is because the more extraordinary the event, the less credible it must be, and as a miracle defies a natural law - which is impossible - they therefore cannot exist.
That something is incredible doesn't make it impossible. And you cannot declare defiance of natural laws an impossibility, as this makes them unfalsifiable and therefore useless as scientific principles.
I think something else that needs to be made more clear here, though, is that a miracle, by its very nature, is always going to be the least likely occurrence. Highly probable things (like falling down instead of up) are never considered miracles because they are perfectly predicted and explainable as part of the working of our natural world based on what we know of it. Miracles, on the other hand, must be highly unlikely in order to be miracles, or else they are little more than unlikely coincidence.
Consider a world in which everyone has the power to turn water into wine. What great wonder is it, then, when one man at a party performs this trick to keep the booze flowing? But in a world where the last thing we would expect to get from a clean jug filled with water is anything other than water, getting wine out of it can indeed be considered a miraculous event.
To be a miracle, something has to be highly improbable; it has to be the least probable of all possible explanations. Thus, it is always irrational to conclude that a miracle happened because there is always a significantly better explanationthat the person telling you is lying, your eyes are playing tricks on you, etc.
Concluding 'miracle' is always the least rational position, so no rational person should ever conclude 'miracle'. This doesn't mean miracles don't happen; it merely means we cannot honestly ever conclude that they do.
Jon

Love your enemies!

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Tangle
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Posts: 9489
From: UK
Joined: 10-07-2011
Member Rating: 4.9


Message 7 of 72 (657862)
03-31-2012 1:05 PM


Mr Jack, NoNukes, nwr, John
We seem to be agreed that it can never be rational to accept a miracle because we can never get to the necessary level of evidence.
Even so, miracles could still exist, it's just never rational to believe in them.
Ok. But that sounds like 'we can't logically rule it out, but given the arguments so far, plus what we think we know of the world, we think it so bloody unlikely that we might as well say, "stuff it, for all practical purposes they can't exist"'
Taking it to the next step and ruling miracles out completely, requires the moves
1. a miracle defies natural laws
2. Natural laws are all there are
3. Miracles can't exist
Being pragmatic, I'll happily accept 2 at face value, until proven wrong.
But hang on, as it's never rational to believe in miracles, I can never be proven wrong.......
Edited by Tangle, : Typo

Life, don't talk to me about life - Marvin the Paranoid Android

Replies to this message:
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 Message 10 by Rahvin, posted 03-31-2012 3:11 PM Tangle has replied
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NoNukes
Inactive Member


Message 8 of 72 (657868)
03-31-2012 1:58 PM
Reply to: Message 7 by Tangle
03-31-2012 1:05 PM


We seem to be agreed that it can never be rational to accept a miracle because we can never get to the necessary level of evidence.
I don't agree with your summation of my position. I agree that it would be rational to reject miracles for lack of sufficient, extraordinary evidence, but I don't agree that accepting that miracles exist despite the lack of such evidence is irrational.
Even so, miracles could still exist, it's just never rational to believe in them.
Perhaps that's true, but you haven't provided a line of reasoning that requires that conclusion.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison

This message is a reply to:
 Message 7 by Tangle, posted 03-31-2012 1:05 PM Tangle has replied

Replies to this message:
 Message 11 by Tangle, posted 03-31-2012 3:20 PM NoNukes has replied

  
Jon
Inactive Member


Message 9 of 72 (657869)
03-31-2012 2:10 PM
Reply to: Message 7 by Tangle
03-31-2012 1:05 PM


I think you're trying to apply scientific principles to something that is very much not scientific.
And I see no reason why we should think this is a reasonable practice.

Love your enemies!

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Rahvin
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Posts: 4032
Joined: 07-01-2005
Member Rating: 9.2


Message 10 of 72 (657870)
03-31-2012 3:11 PM
Reply to: Message 7 by Tangle
03-31-2012 1:05 PM


The flaw in this line of reasoning is extremely simple, and should be obvious:
1. a miracle defies natural laws
2. Natural laws are all there are
3. Miracles can't exist
If our understanding of the natural laws were perfect, this argument would make sense.
Unfortunately, humanity is not collectively omniscient. Our understanding of nature's laws is incomplete.
Many scientific breakthroughs bear the appearance of being "miraculous," because they strongly differ from the way we perceived nature prior to the discovery. Imagine how many "miracles" would be observed by a person transported from 200 years ago to the present day!
An apparently miraculous phenomenon (presuming it's repeatable so that it can be studied, and not simply an aggregate story based on multiple witnesses who are attempting to interpret a confusing observation with only their memories) would be a hint to a new scientific breakthrough, a key to a deeper understanding of the real laws of nature, of which we are always at least to some degree ignorant.
Imagine if, tomorrow, someone discovered a substance that apparently defied gravity when subjected to an electric current. This would appear miraculous...but the real miracle is that we would, for the first time, have a real observational hint toward a deeper understanding of physics (assuming the phenomenon genuinely represents a contrary observation to our basic understanding of gravity, and not merely a misidentified phenomenon relying on a mechanism not at all resembling anti-gravity).
It certainly seems to be true that there are no exceptions to nature's laws, that the basic behavior of the Universe is entirely self-consistent everywhere and at all times. But because our comprehension of those laws and behaviors is incomplete, the apparently miraculous can still occur - confusing phenomenon that contradict currently understood laws are simply the key to understanding what the real laws are.
We should not believe that exceptions to nature's laws exist. But we shouldn't refuse to believe that a phenomenon has occurred only because it appears to contradict our current understanding of those laws, because such phenomenon simply indicate that it is our understanding that is lacking, not the consistency of the Universe itself.

The human understanding when it has once adopted an opinion (either as being the received opinion or as being agreeable to itself) draws all things else to support and agree with it.
- Francis Bacon
"There are two novels that can change a bookish fourteen-year old's life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs." - John Rogers

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Tangle
Member
Posts: 9489
From: UK
Joined: 10-07-2011
Member Rating: 4.9


Message 11 of 72 (657871)
03-31-2012 3:20 PM
Reply to: Message 8 by NoNukes
03-31-2012 1:58 PM


NoNukes writes:
I don't agree with your summation of my position. I agree that it would be rational to reject miracles for lack of sufficient, extraordinary evidence, but I don't agree that accepting that miracles exist despite the lack of such evidence is irrational.
It's irrational to accept a something without evidence is it not? It may be human to do so and it may be ok to do so, but strictly speaking, it would be irrational.

Life, don't talk to me about life - Marvin the Paranoid Android

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Jon
Inactive Member


Message 12 of 72 (657872)
03-31-2012 3:37 PM
Reply to: Message 10 by Rahvin
03-31-2012 3:11 PM


Our understanding of nature's laws is incomplete.
Provided nature even has laws.
Many scientific breakthroughs bear the appearance of being "miraculous," because they strongly differ from the way we perceived nature prior to the discovery. Imagine how many "miracles" would be observed by a person transported from 200 years ago to the present day!
...
But we shouldn't refuse to believe that a phenomenon has occurred only because it appears to contradict our current understanding of those laws, because such phenomenon simply indicate that it is our understanding that is lacking, not the consistency of the Universe itself.
So then what is the difference between 'miracles' and 'unexplained phenomena'?
Imagine if, tomorrow, someone discovered a substance that apparently defied gravity when subjected to an electric current. This would appear miraculous...but the real miracle is that we would, for the first time, have a real observational hint toward a deeper understanding of physics (assuming the phenomenon genuinely represents a contrary observation to our basic understanding of gravity, and not merely a misidentified phenomenon relying on a mechanism not at all resembling anti-gravity).
Scientific discoveries are a pretty regular occurrence. Sometimes the discoveries revolutionize what we know about the world; other times they confirm. In all cases, however, the chain of events is pretty explainable, often being well documented, and always involving pretty mundane techniques (seeing, measuring, calculating, etc.).
To claim that the act of scientific discovery is a miracle is to put yourself in the shoes of that person 'transported from 200 years ago to the present day' who just ignorantly runs around labeling everything that amazes him as 'miraculous'. In this case, however, what is getting the label of 'miracle' isn't even all that amazing: the natural curiosity of the human brain happening upon a discovery that forces it to re-understand the world.
And if this is your metric of the miraculous, what's to stop anything at all from being a miracle?
Jon

Love your enemies!

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Tangle
Member
Posts: 9489
From: UK
Joined: 10-07-2011
Member Rating: 4.9


(1)
Message 13 of 72 (657873)
03-31-2012 3:48 PM
Reply to: Message 10 by Rahvin
03-31-2012 3:11 PM


Rahvin writes:
The flaw in this line of reasoning is extremely simple, and should be obvious........
If our understanding of the natural laws were perfect, this argument would make sense.
Unfortunately, humanity is not collectively omniscient. Our understanding of nature's laws is incomplete.
that would be why I said this I suppose:
But note, while it may well be rational to think that way, it may still be an error as it may be that your understanding of the phenomena is just incomplete.
To give an old example, a solar eclipse would seem miraculous if you hadn't lived in a culture that has the science to understand it.
Followed by this:
Being pragmatic, I'll happily accept 2 at face value, until proven wrong.
But hang on, as it's never rational to believe in miracles, I can never be proven wrong.......
Our understanding of nature's laws ARE incomplete and will always be so. It follows then then we can never say that anything is miraculous because of that same fact. If a limb ever does grow back spontaneously, we can never say that it was a miracle because we can never be sure that there's not a natural process that could do it.
But we both know it's not going to happen.

Life, don't talk to me about life - Marvin the Paranoid Android

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NoNukes
Inactive Member


Message 14 of 72 (657874)
03-31-2012 4:29 PM
Reply to: Message 11 by Tangle
03-31-2012 3:20 PM


It's irrational to accept a something without evidence is it not?
No, not necessarily. Did you make your mom prove that an iron was hot before you elected to follow her advice about not touching it? Should you have done so? Was trusting your mom irrational?
It may be human to do so and it may be ok to do so, but strictly speaking, it would be irrational.
If the above is true, then perhaps the value of rationality is overstated.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison

This message is a reply to:
 Message 11 by Tangle, posted 03-31-2012 3:20 PM Tangle has replied

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nwr
Member
Posts: 6408
From: Geneva, Illinois
Joined: 08-08-2005
Member Rating: 5.1


Message 15 of 72 (657875)
03-31-2012 4:46 PM
Reply to: Message 7 by Tangle
03-31-2012 1:05 PM


Tangle writes:
We seem to be agreed that it can never be rational to accept a miracle because we can never get to the necessary level of evidence.
I'd be cautious about saying "never". Science advances, in part, by finding newer and better ways of getting evidence.

Jesus was a liberal hippie

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