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Posted: 13 February 2009 07:16 PM   [ Ignore ]   [ # 31 ]
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Wandering, in the face of a plethora of excellent arguments showing the fallacy and irrationality of your premises, you seem incapable of separating the facts of an argument from the personality and beliefs of the person.  That is a major flaw in your thinking.  An argument must stand or fall based on the data and logic presented, not on the attitudes or beliefs of the person presenting them. 

I frequently argue with two very politically conservative friends.  They are both intelligent and knowledgeable.  Similarly, I have politically liberal friends.  I don’t mistrust any of them, however, when they offer a premis with which I’m not familiar, I’ll check it out to verify it.  It isn’t that I don’t trust them, but that I need to be satisfied that, if I use that data, I can justify it.  If a liberal were to offer strong evidence to support a conservative position, or the reverse, I would still check out the data to be sure it was correct.  So bias has nothing to do with trust.

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Posted: 15 February 2009 10:51 AM   [ Ignore ]   [ # 32 ]
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I will try and give an example to which you agree.

Suppose a person tells me she saw a dead relative, and he was talking to her.

Should I believe her?

If I know that she loved him very much, this means she is biased in favor of not being skeptical, and therefore a more biased, less objective witeness.

Do you agree?

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Posted: 15 February 2009 11:15 AM   [ Ignore ]   [ # 33 ]
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The basis for making the decision, wandering, is the fact that dead people don’t talk. Therefore, the statement must be false. The identify of the speaker, their relationship with the dead person, or their relationship with you don’t matter. Nor does their gender, religious affiliation, political party, level of education, income level, race, or anything else! Your first line of reasoning is always “Just the facts, ma’am.”

Sure, there are complicated situations where you might want to take into account the reliability of the witness. But you seem to have missed sight of the basics. Until you can hoist aboard the basic principles of reasoning, there’s not much point in talking about these more complicated situations.

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Posted: 15 February 2009 11:32 AM   [ Ignore ]   [ # 34 ]
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Chris Crawford - 15 February 2009 11:15 AM

The basis for making the decision, wandering, is the fact that dead people don’t talk. Therefore, the statement must be false. The identify of the speaker, their relationship with the dead person, or their relationship with you don’t matter. Nor does their gender, religious affiliation, political party, level of education, income level, race, or anything else! Your first line of reasoning is always “Just the facts, ma’am.”

Sure, there are complicated situations where you might want to take into account the reliability of the witness. But you seem to have missed sight of the basics. Until you can hoist aboard the basic principles of reasoning, there’s not much point in talking about these more complicated situations.

How can you substantiate your claim that dead people don’t talk? (I guess you meant to say : the claim that “ghosts do not exist”).


For all I know, ghosts _can_ exist, though I don’t have reason to believe that they do. So, I am going back :

If a person tells me he saw a ghost, and I know he had a great psychological need in seeing one, then his testimony is less reliable.  Agreed?

[ Edited: 15 February 2009 11:36 AM by wandering ]
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Posted: 15 February 2009 11:50 AM   [ Ignore ]   [ # 35 ]
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How can you substantiate your claim that dead people don’t talk?

Because I have mountains of evidence in support of that my claim. Billions of people have lived and died, and I have never conversed with a single one. I have never seen any clear evidence that dead people can talk. In the face of this mountain of evidence, the claim of an individual to the contrary is insignificant. It doesn’t matter who the claimant is: my best friend, my wife, my parents, my siblings, the Pope, the President, a Supreme Court Justice or even that paragon of integrity, an actor in a television commercial. No individual witness can provide evidence sufficient to overrule the mountain of evidence I already possess.

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Posted: 15 February 2009 11:59 AM   [ Ignore ]   [ # 36 ]
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Chris Crawford - 15 February 2009 11:50 AM

How can you substantiate your claim that dead people don’t talk?

Because I have mountains of evidence in support of that my claim. Billions of people have lived and died, and I have never conversed with a single one. I have never seen any clear evidence that dead people can talk. In the face of this mountain of evidence, the claim of an individual to the contrary is insignificant. It doesn’t matter who the claimant is: my best friend, my wife, my parents, my siblings, the Pope, the President, a Supreme Court Justice or even that paragon of integrity, an actor in a television commercial. No individual witness can provide evidence sufficient to overrule the mountain of evidence I already possess.


You are claiming “absence of evidence is evidence of absence”.

The structure of the argument is the folliwing.

If X exists, then we should have evidence in the form of P.
We do not have evidence in the form of P
Thus X doesn’t exist.


But the first premise isn’t true when it comes to ghosts. If ghosts exist then we should have evidence for them? Why? How do you know that? Knowing nothing about the essence of ghosts, you cannot claim that if they existed, the evidence should be available.

So in this case the argument doesn’t hold. You cannot have a positive good case for the lack of ghosts, you can just say that a good case has not been presented.


But this is slightly off-topic Do you agree with what I said about bias :

wandering - 15 February 2009 11:32 AM

If a person tells me he saw a ghost, and I know he had a great psychological need in seeing one, then his testimony is less reliable.  Agreed?

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Posted: 15 February 2009 12:20 PM   [ Ignore ]   [ # 37 ]
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You are claiming “absence of evidence is evidence of absence”.

I most certainly am not. I have a plethora of negative evidence, not an absence of positive evidence. There’s a huge difference between the two. Here’s the real structure of the argument:

If X exists, then we should have evidence in the form of P.
We have carried out billions of tests and each test has yielded negative results.
Thus X doesn’t exist.

Of course, a good scientist always accepts the possibility that one test will yield positive results, and that this would change things. But with so much evidence in place, the choice between the two hypotheses (“X exists” versus “X does not exist”) should be an easy choice to make.

Knowing nothing about the essence of ghosts, you cannot claim that if they existed, the evidence should be available.

If you want to claim that ghosts have no properties, then, yes, it’s easy to prove that the existence of ghosts cannot be refuted. That’s because, lacking any properties, ghosts are nonentities, and nothingness certainly exists. The problem comes as soon as you assign a property to ghosts, such as the ability to talk. That property means that we should be able to talk to ghosts. But I have never conversed with a ghost, nor has anybody ever come up with clear evidence of having spoken to a ghost, despite many claims to that effect. I have never seen a positron, but other people have come up with clear evidence that positrons exist. If nobody had ever tried to talk with a ghost, then you’d have a case, but there have been many attempts, and they have all yielded negative results. That’s not absence of evidence, that’s very solid evidence of absence.

You again ask me to answer your question:

f a person tells me he saw a ghost, and I know he had a great psychological need in seeing one, then his testimony is less reliable.  Agreed?

No, his testimony cannot be less reliable, because the reliability of any such claim by any individual is already zero, and you can’t have reliability less than zero.

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Posted: 15 February 2009 12:24 PM   [ Ignore ]   [ # 38 ]
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Chris Crawford - 15 February 2009 12:20 PM

If X exists, then we should have evidence in the form of P.
We have carried out billions of tests and each test has yielded negative results.
Thus X doesn’t exist.

So what type of evidence should we have, if ghosts exist?

We know that ghosts have proprties if they exist (everything that exists must have some properties…), but we do not know what they are. So we cannot make tests to test the “ghost hypothesis”. Ghosts are “some type of existance after death”. But we do not know any specifics about “existance after death”.

[ Edited: 15 February 2009 12:28 PM by wandering ]
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Posted: 15 February 2009 12:30 PM   [ Ignore ]   [ # 39 ]
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We know that ghosts have proprties if they exist (everything that exists must have some properties…), but we do not know what they are. So we cannot make tests to test the “ghost hypothesis”.

Hold on! You were describing ghosts talking. So that’s your property. And I have never spoken with a ghost, and I don’t know anybody who has ever spoken with a ghost, and there have been many attempts to talk with ghosts, and none of them have ever yielded objectively convincing results. Again, if nobody had ever attempted to speak with ghosts, you might have a case, but there have been lots of attempts, and they have all failed to produce objectively convincing results.

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Posted: 15 February 2009 12:45 PM   [ Ignore ]   [ # 40 ]
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Chris Crawford - 15 February 2009 12:30 PM

We know that ghosts have proprties if they exist (everything that exists must have some properties…), but we do not know what they are. So we cannot make tests to test the “ghost hypothesis”.

Hold on! You were describing ghosts talking. So that’s your property. And I have never spoken with a ghost, and I don’t know anybody who has ever spoken with a ghost, and there have been many attempts to talk with ghosts, and none of them have ever yielded objectively convincing results. Again, if nobody had ever attempted to speak with ghosts, you might have a case, but there have been lots of attempts, and they have all failed to produce objectively convincing results.

Anyway, thats not important.

The issue, for me is that if someone says that he has talked to a ghost, if he is biased strongly towards believing in them for psychological reasons, makes his testimony less reliable.

People here seem to disagree. You disagree because you say that his reliability is zero anyway.

So think of an example that is less controversial for you -  you tell me which paranormal issue you find at least somewhat probable. With such an issue, do you agree that if someone has a psychological need in favor of believing the claim to be true, he isn’t a reliable witness?

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Posted: 15 February 2009 12:54 PM   [ Ignore ]   [ # 41 ]
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wandering - 15 February 2009 12:24 PM

So what type of evidence should we have, if ghosts exist?

Well, we should have some sort of evidence that ghosts exist. Those who believe that ghosts exist should produce the theory behind their existence (e.g., what sort of evidence they expect to see) and actual evidence that supports their claims. It’s not up to the skeptic to do so.

And BTW, I am going to take the other horn of that implicit dilemma before: absence of evidence is evidence of absence, assuming we’ve looked around a bit. If someone wants to tell me there’s a pink elephant in my basement, and I look around the basement and find an absence of evidence of elephants of any color, that is all the evidence we could ever hope to get that there is no pink elephant down there. To say otherwise is just to be obtuse.

This is the same structure as Russell’s teapot argument: we have no evidence of a teapot in orbit around Mars. But we have no theoretical reason to accept it, either, so the existence of this teapot is something that can be safely discounted until further evidence comes in.

The standard claim re. “absence of evidence isn’t evidence of absence” is a claim about the structure of a deductively logical argument: it is logically consistent (there is no contradiction involved) that we not have evidence for X but nonetheless X be true. But this sort of point is consistent with the methodological point I was making before. Logically, it is possible that things for which we have no evidence might be so. But methodologically, we have no reason to accept them until the evidence comes in.

It is also the case that there is absolutely no method of action for ghosts. The only causal forces we know of are physical forces. We see things because of the reflection of photons of light off of surfaces. We hear things because physical objects cause vibrations in the air. Things move because of Newton’s laws of action and reaction. Ex hypothesi, none of these are true of ghosts. They don’t have any physical attributes; they have no physical surface; they have no physical part that can create vibrations in the air; they can do no physical work.

They are also supposed to have an antecedent life as a person. But once again, all the evidence we have is that the person is identical with the functional workings of the brain. When part of the brain dies, part of the person dies. When the entire brain dies, so does the person. We have absolutely no evidence of persons surviving the death of their brain. So given what we know about physical objects and persons, the existence of ghosts is impossible.

I can’t tell if you are being serious about these arguments, or not. If not, I can’t tell what you are really getting at.

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Posted: 15 February 2009 12:58 PM   [ Ignore ]   [ # 42 ]
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wandering - 15 February 2009 12:45 PM

The issue, for me is that if someone says that he has talked to a ghost, if he is biased strongly towards believing in them for psychological reasons, makes his testimony less reliable.

People here seem to disagree. You disagree because you say that his reliability is zero anyway.

So think of an example that is less controversial for you -  you tell me which paranormal issue you find at least somewhat probable. With such an issue, do you agree that if someone has a psychological need in favor of believing the claim to be true, he isn’t a reliable witness?

What Chris said before. For all I know, he may be a very reliable witness generally; the mere fact that he says he’s talked with a ghost doesn’t necessarily make him globally unreliable. (Everyone has their quirks!)

It’s rather that the hypothesis of the existence of ghosts is so improbable that a single anecdotal account is worthless. You are double-counting the epistemic value of this encounter if you both discount the evidence for ghosts itself and the reliability of the witness for having asserted the existence of ghosts.

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Posted: 15 February 2009 01:10 PM   [ Ignore ]   [ # 43 ]
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The existance of ghosts is not my point at all.

Do you agree that a testimony of a person that saw her dead relative is less reliable if - he was very anxious after he died, and wanted to see him very much?
Do you agree that such a testimony (however unreliable it is to you), is less reliable than the testimony of a less “biased” person?

[ Edited: 15 February 2009 01:15 PM by wandering ]
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Posted: 15 February 2009 01:15 PM   [ Ignore ]   [ # 44 ]
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dougsmith - 15 February 2009 12:54 PM
wandering - 15 February 2009 12:24 PM

So what type of evidence should we have, if ghosts exist?

Well, we should have some sort of evidence that ghosts exist. Those who believe that ghosts exist should produce the theory behind their existence (e.g., what sort of evidence they expect to see) and actual evidence that supports their claims. It’s not up to the skeptic to do so.

And BTW, I am going to take the other horn of that implicit dilemma before: absence of evidence is evidence of absence, assuming we’ve looked around a bit. If someone wants to tell me there’s a pink elephant in my basement, and I look around the basement and find an absence of evidence of elephants of any color, that is all the evidence we could ever hope to get that there is no pink elephant down there. To say otherwise is just to be obtuse.

This is the same structure as Russell’s teapot argument: we have no evidence of a teapot in orbit around Mars. But we have no theoretical reason to accept it, either, so the existence of this teapot is something that can be safely discounted until further evidence comes in.

Ghosts are a cultural myth about life-after-death. Even if some form of life-after-death exists, it is probably very different from our naive conceptions of “ghosts”.

I agree that absence of evidence is generally evidence of absence.

However, when we are discussing life-after-death, we do not know what type of evidence to look for. The folklore myths about the “ghosts” are no guide at all.  This is why I think “absence of evidence” does not apply here.  It might be that there is some form of disembodied and disbrained life, but we do not know how to even start testing the ideas, and folklore-tales are not a good start.

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Posted: 15 February 2009 01:20 PM   [ Ignore ]   [ # 45 ]
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So think of an example that is less controversial for you -  you tell me which paranormal issue you find at least somewhat probable. With such an issue, do you agree that if someone has a psychological need in favor of believing the claim to be true, he isn’t a reliable witness?

I think that the problem here is more fundamental than you realize. You’re attempting to establish truth on the basis of human subjective testimony. Science doesn’t place any trust in human subjective testimony, unless it is measuring human subjective factors. To determine objective truth, science always puts its money on objective measurements. There are a few rare cases in which human subjective testimony is the only data we have, and in those cases we make whatever use we can of that evidence, but we don’t hang a case on that testimony. For example, there was recently a big meteorite fall in Canada. Lots of people reported it. If that were all we had, we would have shrugged our shoulders and said, gee, isn’t that nice; a big meteor fell. But a lot of the people reported the direction in which they saw it fall, and a scientist collated the reports of dozens of people. Had he relied on only one or two observers, that evidence would have been completely useless. But by combining all that data, he was able to get a rough estimate of where the meteorite should have fallen. He then traversed the area, which fortunately was blanketed in snow of just the right depth. Too deep and the meteorites would not have left a visible crater; too shallow and the craters left by the meteors would have been indistinguishable from normal open spots. But the snow was just the right depth so that the meteorite impacts left nice big brown craters in the otherwise pure white snowfields. He was thereby able to locate the area of impact and collect a good many specimens.

The human testimony was useful as a starting point for a bootstrapping process that ultimately led to useful scientific results. But that testimony all by itself was useless; its only value arose from the fact that it could be used to obtain objectively solid evidence (the meteorites).

You seem to think that human testimony has some value in determining objective truth. It doesn’t. Yes, you can learn about human subjective traits from human testimony. But you can’t learn much at all about objective truth from human testimony. Therefore, you’re starting off going down the wrong road trying to figure out what kind of human testimony is more reliable or less reliable for establishing truth. It’s not at all reliable in the first place. If you want to know how long your car is, you could ask twenty people to estimate its length, or you could pull out a measuring tape and just measure it directly. Arguing about whether Jack’s estimate is better than Jill’s estimate is a waste of time.

There is one interesting variation on this involving witness testimony in a criminal trial, but that raises many other issues, the most important of which is that we all know the witness testimony to be intrinsically unreliable.

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