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.

Yes, there is always the realm of the unknown. But we always know something about the world that limits the range of the unknown. Nobody had ever visited the deep sea floor prior to the latter half of the 20th century, but that doesn’t mean that people would have been justified in 1900 in claiming the existence of an Atlantis-type civilization dwelling on the floor of the Atlantic Ocean. Why? Because there was no evidence in favor of the claim! Yes, the absence of evidence is not evidence of absence, but the absence of evidence is surely not evidence of presence!

Chris Crawford - 15 February 2009 01:25 PM

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.

Yes, there is always the realm of the unknown. But we always know something about the world that limits the range of the unknown. Nobody had ever visited the deep sea floor prior to the latter half of the 20th century, but that doesn’t mean that people would have been justified in 1900 in claiming the existence of an Atlantis-type civilization dwelling on the floor of the Atlantic Ocean. Why? Because there was no evidence in favor of the claim! Yes, the absence of evidence is not evidence of absence, but the absence of evidence is surely not evidence of presence!

I agree with that.

Chris Crawford - 15 February 2009 01:20 PM

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.

I fail to see the reason why testimony cannot be used to determine objective truth. You are right in that objective evidence is a better guide. You are right that testimony is often unreliable. But making the argument that

Testimony is often wrong
Therefore we cannot rely on testimony to determine objective truth

is not a good argument.

I can agree to put testimony as the least reliable tool to measure objective truth - but this is different from using it as a tool at all.

I can agree to put testimony as the least reliable tool to measure objective truth - but this is different from using it as a tool at all.

I agree with that. But now the problem is to come up with instances in which human testimony has evidentiary value. The obvious example is human testimony in a criminal trial. But I’m hard put to think of any scientific applications of human testimony.

wandering - 15 February 2009 01:15 PM

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.

If there is some form of life-after-death, and it is very different from our naïve conception of “ghosts”, then what is it like? What model are you proposing?

One can always make the claim that there is some sort of stuff we-know-not-what, that behaves in some manner with which we are entirely unfamiliar, and that we have no evidence for. But such claims are methodologically worthless. If, as you put it, “we do not know how to even start testing the ideas”, and indeed all we know about these ideas is that they are “probably very different from our naïve conception”, it certainly sounds like these ideas may be vacuous.

There is no point in worrying about vacuous ideas.

If you have a particular model of what constitutes life-after-death, then put it on the table and we can discuss the likelihood for it. Until then, it’s a waste of time to consider it, since there’s nothing yet to consider.

I don’t see how the role of testimony has anything to do with this case.

dougsmith - 15 February 2009 02:35 PM

If there is some form of life-after-death, and it is very different from our naïve conception of “ghosts”, then what is it like? What model are you proposing?

One can always make the claim that there is some sort of stuff we-know-not-what, that behaves in some manner with which we are entirely unfamiliar, and that we have no evidence for. But such claims are methodologically worthless. If, as you put it, “we do not know how to even start testing the ideas”, and indeed all we know about these ideas is that they are “probably very different from our naïve conception”, it certainly sounds like these ideas may be vacuous.

There is no point in worrying about vacuous ideas.

If you have a particular model of what constitutes life-after-death, then put it on the table and we can discuss the likelihood for it. Until then, it’s a waste of time to consider it, since there’s nothing yet to consider.

I don’t see how the role of testimony has anything to do with this case.

If a person testifies he saw ghosts - is he a less reliable witness because he is biased in believing in them?

I think yes, and people here seem to disagree. The “ghosts” example is only an instrument to discuss the bias issue, it wasn’t important in itself. (And I do not have a specific model of life-after death. )

We know two things about gods, ghosts and the like:

(1) There is no reliable evidence to support their existence, and

(2) People are inclined to believe in them anyway.

In other words, we know something about ourselves, how we think and what we are inclined to think about. The best response is to be cautioned about taking any of the various claims seriously, and at the same time to take very seriously the rather obvious weaknesses in humanity’s thought processes. Instead, we tend to spend considerable time dissecting the “merits” of a debate we don’t even know how to frame.

wandering - 16 February 2009 01:30 AM

If a person testifies he saw ghosts - is he a less reliable witness because he is biased in believing in them?

Well, this is kind of an odd case, since his very testimony assumes he believes in ghosts. That is, you don’t add any information to the testimony by telling me that he believes in ghosts. If he didn’t believe in ghosts, he wouldn’t have described his experience with those words.

(And I still don’t see what the word “biased” is doing here. Again, it appears to me to be a way of describing a belief that you don’t agree with).

There are various things we should say about this case:

(1) What, precisely, did this person witness? A white light? Something moving? A thick fog? A noise? Let’s get a more precise description, since “ghost” covers so many possibilities. It’s a vague and loaded descriptor.

(2) If the person witnessed something, it has to be something that can interact with physical matter—e.g., it has to reflect light, or cause vibrations in the air, or move objects. That is, it must be at least partly physical. So we can start looking there. (Assuming, of course, that this wasn’t some species of hallucination; something we cannot completely rule out, even with very reliable witnesses).

Insofar as you’re discussing reliable testimony, it certainly seems to me that the reliability of any given witness has to be gauged without reference to the specific case in question. That is, if you want to know whether this person is reliable, you have to look at everything else that he’s witnessed, and not this case in particular. That will give you a global indicator of his reliability, which you can then put to this particular case.

But even if he’s an extremely reliable witness generally, that will simply establish that he saw something (e.g., a fuzzy light), not that he saw a ghost. That he saw “a ghost” is to say more than he would have evidence for. In order to establish that he saw a ghost we would need to know that the existence of ghosts was a live possibility—we would need to have evidence for life after death, for the spooky interaction of souls and material objects, etc. Were we to gather all that evidence and marshall it into a theory that supported the existence of ghosts, then depending on the case, we might say that this witness was reliable in this case. But without that background evidence (which anyhow, as I’ve said, we completely lack), we can say that although this witness may well be extremely reliable, he has misdescribed his experience in this case.

I’m giving up on this discussion. Wandering, I don’t think that you have absorbed the basic point that I and others have been hammering away at: that truth is determined objectively, not subjectively. We have made this point in many different ways, from many different angles, and you just keep ignoring it and arguing about the relative validity of subjective evidence based on the state of mind of the witness. Yes, of course, the state of mind of the witness affects the reliability of the testimony. But state of mind is an immensely complicated concept.

Let me give you an example. I have long suspected that shower meteors underwent a disintegration process from their parent comet that involved larger particles breaking into smaller particles in a serial process. This implies that observed meteors should be temporally nonrandom. I have been pursuing this concept for 40 years now (although 40 years ago my conceptualization was considerably more primitive). I have carried out a number of observations and analyses to find compelling evidence in support of my hypothesis. So I am clearly biased in favor of the hypothesis. Yet I’m also no fool and I have never treated it as more than a hypothesis, because until I can come up with that compelling evidence, I know that I cannot convince anybody else of it.

So, suppose that the analysis of Leonid storm meteors that I am currently working on produces what I consider to be compelling evidence in support of my hypothesis. Suppose that I then publish these results. Would you dismiss my results because I am biased in favor of the hypothesis? Are you confident enough in your estimate of my state of mind that you can reject my results based on my state of mind rather than the evidence itself?