Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
7 online now:
Newest Member: popoi
Post Volume: Total: 915,809 Year: 3,066/9,624 Month: 911/1,588 Week: 94/223 Day: 5/17 Hour: 1/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Absence of evidence IS evidence of absence
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 8 of 89 (64719)
11-06-2003 9:59 AM
Reply to: Message 2 by crashfrog
11-06-2003 8:57 AM


Crash, I think DNA is making a very good point. He has been clear that absence of evidence isn't a proof of anything untill ALL possible searches have been done.
A problem may be that you are trying to be black and white. For example, in the football analogy. No one would conclude there is no football after looking at one blade of grass. But after some number of random searches (short of the whole field) more and more of us will conclude there is no football. The line between "I don't know if the football is there" and "It ain't there" isn't sharpe. We would all drift over it with differing amounts of evidence and many of us would be in a middle zone for awhile.
I was once at a lecture of Freeman Dyson's. For some reason the issue of extraterristrials came up. I asked what his take on the subject was. He said something like 'Unfortunately I have to conclude they are not there'. Why? Where are they? Absense was as much evidence as he had and he was willing to draw a conclusion from that (tentively perhaps).

This message is a reply to:
 Message 2 by crashfrog, posted 11-06-2003 8:57 AM crashfrog has not replied

Replies to this message:
 Message 10 by Dr Jack, posted 11-06-2003 10:11 AM NosyNed has replied
 Message 16 by Rei, posted 11-06-2003 1:23 PM NosyNed has not replied
 Message 84 by Peter, posted 12-02-2003 11:39 AM NosyNed has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 11 of 89 (64727)
11-06-2003 10:34 AM
Reply to: Message 10 by Dr Jack
11-06-2003 10:11 AM


I think both sides of this agree to some degree. We do NOT have enough evidence to conclude anything firmly. They are both just coming down on their favourite side of the arguement. Some people just like to carry the arguement on further than it needs to be.
A single data point is not evidence for anything.
Yes it is! It isn't very much evidence but it is evidence. The chances of the football being there are just a shade smaller now. And if the football had been there that single data point would have been very strong evidence.

This message is a reply to:
 Message 10 by Dr Jack, posted 11-06-2003 10:11 AM Dr Jack has replied

Replies to this message:
 Message 12 by Dr Jack, posted 11-06-2003 10:40 AM NosyNed has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 35 of 89 (64966)
11-07-2003 1:48 PM
Reply to: Message 34 by Rei
11-07-2003 11:45 AM


I'm not sure you're right about this Rei. Maybe when a number of separate points are made it is helpful to chop them into separate posts. There is always a chance that any one of them might be the root of a new branch of discussion and posting a reply to the specific one might make it clearer.
Of course, if they aren't really separate then the chopping up makes it less clear as you say. I guess it is a judgement call.
Everyone will have a slightly different organizational style. I think you need to be a bit less sensitive to the differences. At least DNA supplies complete sentences and paragraphs. There is a limit to how much presentation style idiosynchracies one can take .

This message is a reply to:
 Message 34 by Rei, posted 11-07-2003 11:45 AM Rei has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 50 of 89 (65281)
11-09-2003 12:34 AM
Reply to: Message 49 by DNAunion
11-08-2003 11:05 PM


This is getting silly!
DNA has stated very, very clearly that absence of evidence is "evidence" not "proof". And it clearly is evidence.
All of us, (well maybe not the mathematician ) will decide after enough work that continued absence of evidence IS "proof" of absence. How soon we make that leap will depend on what the totallity of evidence is like.
We have not drained Loch Ness to look for the wee beastie have we? However, a variety of reasoning on ecology and the absence of any good evidence leads most of us to conclude that the laddie isn't home doesn't it? We may well accept that it isn't perfect "proof" but we act as if it is. We will not bet our life savings on him being there. We don't finance yet another search. We take the existing evidence including the fruitless searchs as input (i.e., evidence) that he just isn't home. (which I'm sad about actually).
Enough already! geez

This message is a reply to:
 Message 49 by DNAunion, posted 11-08-2003 11:05 PM DNAunion has not replied

Replies to this message:
 Message 53 by crashfrog, posted 11-09-2003 6:10 AM NosyNed has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 54 of 89 (65305)
11-09-2003 10:32 AM
Reply to: Message 53 by crashfrog
11-09-2003 6:10 AM


I agree with you on the other thread Crash. Misuse of this idea doesn't in the other thread doesn't mean it is wrong though.
However, I also agree with you on the distinction you are making in your previous post. Saying absence of evidence *is* evidence of absence isn't really saying all that much really.
It doesn't say it is very good evidence. That will depend on the details of the specific case.

This message is a reply to:
 Message 53 by crashfrog, posted 11-09-2003 6:10 AM crashfrog has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 56 of 89 (65428)
11-09-2003 5:56 PM
Reply to: Message 55 by Rei
11-09-2003 4:38 PM


Hang on. What you are asking is: "Is it proof?"
We all agree that it is not proof. Therefore a conclusion drawn on absence of evidence could very well be wrong.
Is a negative finding evidence for anything at all? Yea, I think we agree on that. Can you always extrapolate from a small set of negative results? Sure you can. Will you be right some of the time? Yes. Will you be wrong some of the time? Yes.
The question is: "When can we decide to start using absence of evidence for *good* (ie. useful) evidence of absence?" Can I answer in general? No.
As far as the universe case goes, we haven't done much of a search, as you say, and we don't know enough to make other judegements about the likelyhood of what we are looking for. The situation is simply not decideable yet.

This message is a reply to:
 Message 55 by Rei, posted 11-09-2003 4:38 PM Rei has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 61 of 89 (65489)
11-09-2003 10:40 PM
Reply to: Message 60 by crashfrog
11-09-2003 10:33 PM


Oh come on Crash. Of course, we can argue about inconclusive positions. If there is a lot of evidence for both sides an really interesting discussion of it all may be a way to arrive at some sort of conclusion.
It may also be away to find that we simply don't have enough evidence to get both sides to arrive at the same tentative conclusion but maybe will figure out what is needed to pick between them.
If there is very little evidence then there isn't much good having an argument. That is, if the proposition is VERY inconclusive. As DNA points out if it is completely "conclusive" then there is also not much room for argument. (Though that hasn't stopped the YEC'ers has it? )
As for the life as we know it thing I'd say it is in the too little information available to do more than arrive at a "We don't know, let's wait and see" position.
I think you both are approximately are at that position but neither of you seem to be able to keep from making a step (with no evidence) to where you'd like the answer to be.

This message is a reply to:
 Message 60 by crashfrog, posted 11-09-2003 10:33 PM crashfrog has replied

Replies to this message:
 Message 62 by crashfrog, posted 11-09-2003 11:42 PM NosyNed has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 63 of 89 (65513)
11-10-2003 12:55 AM
Reply to: Message 62 by crashfrog
11-09-2003 11:42 PM


Ok, I'll let DNA clarify that for us. He can do that in the other thread and that will (or won't) settle it.

This message is a reply to:
 Message 62 by crashfrog, posted 11-09-2003 11:42 PM crashfrog has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 78 of 89 (66864)
11-16-2003 1:19 PM
Reply to: Message 77 by crashfrog
11-16-2003 12:55 PM


I think we never got to that much detail. Everyone just kept arguing about if AoE could be EofA without getting clear what criteria there might be for AoE being good, bad or so-so evidence. If you want to firm that up a bit now it might be a good idea.

This message is a reply to:
 Message 77 by crashfrog, posted 11-16-2003 12:55 PM crashfrog has replied

Replies to this message:
 Message 79 by crashfrog, posted 11-16-2003 1:24 PM NosyNed has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024