"Absence of evidence isn't the evidence of absesence."

derchin · 6th May 2012, 08:36 PM

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

AdMan · 6th May 2012, 08:38 PM

What's your point of view?

slingblade · 6th May 2012, 08:48 PM

Yes, let's please do hear what you make of it, first.

Kid Eager · 6th May 2012, 08:52 PM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

the need for a better spellchecker

Brian-M · 6th May 2012, 08:53 PM

Originally Posted by derchin

What do you make of it?

Absence of evidence isn't evidence of absence... except where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found.

For example, if there have been persistent rumors of a yeti living in a local forest for decades, the fact that nobody's managed to provide evidence of a yeti living there isn't evidence that there isn't one there.

But if you have hundreds of people systematically search the forest for evidence of a yeti and you find no evidence of a yeti in the forest, then this counts as evidence of absence of a yeti because you'd normally find some evidence of any large life forms living in the forest by that method.

(Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.)

shadron · 6th May 2012, 09:01 PM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

Johnny says: "This? Why, I can make a hat, or a brooch, or a pterodactyl..."

slingblade · 6th May 2012, 11:03 PM

Originally Posted by shadron

Johnny says: "This? Why, I can make a hat, or a brooch, or a pterodactyl..."

Looks like I picked the wrong week to quit sniffing glue....

devnull · 6th May 2012, 11:25 PM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

It is, on the face of it, true.

Unfortunately people take the next step, which is "and therefore, you should judge it a possibility".

Beelzebuddy · 6th May 2012, 11:57 PM

Quote:

Absence of evidence isn't evidence of absence.

But it does waggle its eyebrows suggestively in that direction.

Dunstan · 6th May 2012, 11:58 PM

What I make of it is: the null hypothesis wins.

And, for the record, the null hypothesis is not "whatever the majority of people in my culture believe."

Marquis de Carabas · 7th May 2012, 12:05 AM

I've always been mildly disturbed by the assertion. I'll buy "absence of evidence is not proof of absence", but it really is evidence. It just always seemed obvious to me that the saying was wrong. You get home, you call your wife's name and get no answer, you check all the rooms and don't see her. You have an absence of evidence that she is home, which is pretty good evidence that she is not home, no? True, she could be in the attic, or perhaps dodging just ahead of you from room to room, or hell, maybe you're secretly Reed Richards, but it's likely she just isn't there, based entirely on the absence of evidence that she is.

Of course, I realize that's just sort of armchair reasoning, so it was with some delight a few years ago that it turned out I'm not the only one who feels this way, and others have expressed it far more rigorously than I have above. Turns out, I'm just a Bayesian.

http://lesswrong.com/lw/ih/absence_o...ce_of_absence/
http://blog.sigfpe.com/2005/08/absen...idence-of.html

Last of the Fraggles · 7th May 2012, 01:06 AM

Absence of evidence quite clearly is evidence of absence.

For example, if a murder was committed and you were accused of it then the fact that not a trace of you could be found at the scene would be provided as evidence that you weren't there and didn't do it.

It may not be conclusive evidence, but it is evidence. The strength of which is largely dictated by what we would expect to find.

Where it all gets silly is when the theist try to justify the absence of evidence.

'Of course he didn't leave any hair at the scene...he is able to shed all his hair at will and did so prior to entering the apartment.'

'Of course there are no footprints...he can levitate'

'Of course there is no DNA, he doesn't have any. In any case, he didn't need to enter the apartment. He could have killed him with the power of his mind'

'And how does that work?'

'Um..magic'

'Really?'

'You can't prove me wrong!!!!!!!!!!!!'

P.J. Denyer · 7th May 2012, 03:40 AM

Originally Posted by Brian-M

Absence of evidence isn't evidence of absence... except where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found.

For example, if there have been persistent rumors of a yeti living in a local forest for decades, the fact that nobody's managed to provide evidence of a yeti living there isn't evidence that there isn't one there.

But if you have hundreds of people systematically search the forest for evidence of a yeti and you find no evidence of a yeti in the forest, then this counts as evidence of absence of a yeti because you'd normally find some evidence of any large life forms living in the forest by that method.

(Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.)

This, absence of evidence may not be proof of absence, but it certainly can be evidence.

paiute · 7th May 2012, 04:25 AM

Originally Posted by slingblade

Looks like I picked the wrong week to quit sniffing glue....

Hey... knock a self a pro, Slick! That gray matter backlot perform us DOWN, I take TCB-in', man!

Darat · 7th May 2012, 04:28 AM

Originally Posted by Brian-M

...snip...

(Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.)

And if you can say that fives times fast then it is evidence of an absence of alcohol in your bloodstream!

Dancing David · 7th May 2012, 04:35 AM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

The burden of proof lies on the positive claim.

HansMustermann · 7th May 2012, 04:46 AM

I'd even quite happily leave it at "Absence of evidence isn't the evidence of absesence," but with the caveat that absence of evidence is also no reason to assume that something exists. Yes, there is always some tiny chance that we just didn't look in the one hidden cave where the world's only yeti lives, or we didn't stumble upon the exact spot where the dimensional portal to Santa's workshop is, but in the meantime there is also no rational reason to believe in them without any evidence that requires a yet or Santa to explain.

Really, it's just Occam's Razor, and I think most people find it quite natural to apply it to anything except their pet woowoo.

E.g., if I told someone that mom is Wonder Woman and has an invisible airplane, they would want some evidence before they believe either. "You can't disprove that she has an invisible plane" may be technically correct, but it also doesn't mean any rational person should believe it just because lack of evidence for such an invisible plane isn't evidence of absence of said plane.

E.g., to take a sadly more real example, it was (and still is) impossible to prove that people don't fly on a broomstick to the witches' sabbath. You'd think that at least something like her husband testifying that she was at home in bed at the supposed night would be evidence that she didn't go anywhere, or that it was outside a major market and nobody there saw anyone flying or any window or door opening on that house, but they covered that aspect too: see, witches make themselves invisible, and leave a demonic double behind in bed. So really, the best you could have was a complete absence of evidence that such a sabbath exist or anyone goes there. But conversely, I think we can agree, that then there is no reason to assume that one does exist.

Beerina · 7th May 2012, 04:48 AM

Originally Posted by Kid Eager

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

the need for a better spellchecker

And an auto-capitalizer and punctuator.

JoeBentley · 7th May 2012, 05:11 AM

Originally Posted by HansMustermann

I'd even quite happily leave it at "Absence of evidence isn't the evidence of absesence," but with the caveat that absence of evidence is also no reason to assume that something exists.

Exactly. "Absence of evidence isn't evidence of absence" only works in conjunction with the Null Hypothesis. Given the divide between what actually exists and what could possibly exist, working from possible and trying to find reasons why it doesn't exist is, at best, inefficient.

But this is all rather academic. It's blatantly obvious when dealing with Theist and other Woo Slingers that it's not about evidence of absence versus absence of evidence. It's all about them coming up with various malarkey as to why they should just get to make crap up.

Gawdzilla · 7th May 2012, 05:14 AM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

Absence of evidence is evidence of absence. Not absolute proof, but evidence.

HansMustermann · 7th May 2012, 05:27 AM

Originally Posted by JoeBentley

Exactly. "Absence of evidence isn't evidence of absence" only works in conjunction with the Null Hypothesis. Given the divide between what actually exists and what could possibly exist, working from possible and trying to find reasons why it doesn't exist is, at best, inefficient.

But this is all rather academic. It's blatantly obvious when dealing with Theist and other Woo Slingers that it's not about evidence of absence versus absence of evidence. It's all about them coming up with various malarkey as to why they should just get to make crap up.

I don't think it's purely academic, actually. The infinite domain of what could possibly exist (especially if you throw in stuff like "outside the actual universe" or not subject to the laws of physics and such) is actually the main problem with Pascal's Wager, for example.

I've actually done the exercise in a post of talking about what _a_ God could be like. Even taking the basic problems like suicide, murder, human sacrifice, rape, slavery, homosexuality, war in his/her name, etc, and a scale of basically:

1. Strongly condemns and punishes.
2. Is against, but it's not by itself reason to go to Hell.
3. Doesn't give a damn.
4. Is for, but it doesn't earn you a place among the chose by itself.
5. Explicitly commands and rewards.

You get trillions of possible Gods, and you can't play it safe by just picking one because it hasn't been disproven.

And by the way, there are actual religions on Earth where each of those can be a 1 or a 5. You'd think for example homosexuality can't be a 5, i.e., mandatory in any religion, but, really, there is IIRC one tribe where it actually is. What if their god is the right one?

Just saying that it's not reason to assume something, still leaves the possibility to say, "yeah, but I'll play it safe and take a can of Bigfoot repellent anyway." It's only when you can make a point about that big domain of what could exist, and basically "what if you meet a chupacabra instead?", that shows why it's impossible and irrational to even try.

JoeBentley · 7th May 2012, 05:41 AM

And that.

If something actually exists it tends to leave evidence for itself.

The "Prove I'm not wrong!" angle puts people in the odd position of trying to come up with reasons where their pet Woo, which the obviously think is some grand universe changing idea, has absolutely no effect on the world which to me is rather self defeating.

X · 7th May 2012, 05:52 AM

I've said this before in the 9/11 Conspiracy Theory sub-forum:

Absence of evidence is not evidence of absence, but absence of expected evidence can be.

Also, you cannot disprove what I said.

Foster Zygote · 7th May 2012, 06:03 AM

Originally Posted by derchin

Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs.

What do you make of it?

It is essentially correct. But it is important to remember that the inability to disprove something is not a sound reason to argue that it exists.

bjornart · 7th May 2012, 06:22 AM

I'd say it's only true when you haven't looked. Looking and not finding is evidence.

JoeBentley · 7th May 2012, 06:39 AM

Originally Posted by bjornart

I'd say it's only true when you haven't looked. Looking and not finding is evidence.

And to take it one step further purposely not looking doesn't excuse Woo away either.

HansMustermann · 7th May 2012, 06:47 AM

TBH, I don't think it even warrants being made an explicit corollary. There simply is no rational reason to believe something in the absence of evidence. Exactly how and why one lacks evidence is IMHO just a tangent. Lacking evidence for refusing to even look, or lacking evidence because the dog ate the paper, or lacking evidence by virtue of being born in some stone-age tribe in the Amazonian woods, etc, all have the same important part: not having evidence.

JoeBentley · 7th May 2012, 06:52 AM

I don't consider holding opinions as to how the universe works without evidence to be any better then holding opinions as to how the universe works that are counter to the evidence.

Ideas are valid based on positive evidence for them. Lack of evidence against them is really just a double check, a fail safe, a checking your work kinda thing.

Foster Zygote · 7th May 2012, 07:06 AM

Originally Posted by bjornart

I'd say it's only true when you haven't looked. Looking and not finding is evidence.

I agree. But as often put forth by theists, it becomes an epistemological issue of their god or gods being somewhere in the universe where we can't observe. To restate one of my favorite analogies regarding a '67 Dodge Dart orbiting a star in the Andromeda galaxy: Just because we can't survey every star in M31 to check for the presence of the Dodge Dart, it doesn't follow that its presence is any more likely.

Mick Houlahan · 7th May 2012, 08:32 AM

Originally Posted by slingblade

Looks like I picked the wrong week to quit sniffing glue....

Surely you can't be serious.

Skeptic Ginger · 7th May 2012, 08:53 AM

Slogans of wisdom tend to limit thinking.

"Absence of evidence isn't evidence of absence" leads people not to think of things like the exception noted where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found.

In addition, the slogan leads people to assume the false conclusion that said absence is evidence the thing does exist. This slogan is most often use to justify god beliefs. "Absence of evidence isn't evidence of absence" was appropriate when Sagan used to to refer to the current lack of evidence of ET life somewhere out there in the Universe. But it is not equal when the slogan is applied to god beliefs. We have evidence of some life in the Universe, us. There is no evidence of gods thus the slogan cannot be applied in the same way.

Two similar slogans that cause 'no-think' are, "the plural of anecdote is not evidence" and "anecdotes are not evidence". These are even more problematic than the absence of evidence slogan.

First, anecdotes are evidence. What is typically being referred to by the slogan is the conclusion people draw from the anecdote, not the anecdote. Or someone repeats a questionable observation as evidence for something.

All observations are not equal. Some observers and observations are more reliable than others. For example, a trained observer or an eye witness to a crime where the perpetrator is known to the witness are going to result in more reliable 'anecdotes' than an untrained observer or a witness to a crime committed by a stranger respectively. Adding controls to a collection of anecdotes or collecting the anecdotes systematically can also result in a plural of anecdote that is indeed evidence.

If we are going to use these slogans we should understand them. But when they are passed on as memes, quite often they end up beng misapplied and leading critical thinkers down cul-de-sacs instead of down the connecting streets.

aggle-rithm · 7th May 2012, 09:32 AM

Originally Posted by HansMustermann

You get trillions of possible Gods, and you can't play it safe by just picking one because it hasn't been disproven.

It occurs to me that, maybe when we die we go to a sort of divine trade show, where all the possible gods have booths set up and we can stroll around as long as we want until we decide which one of them to go with.

Better be careful, though...the afterlife may not be as advertised, and we'll be stuck with it for quite some time.

aggle-rithm · 7th May 2012, 09:33 AM

Originally Posted by aggle-rithm

It occurs to me that, maybe when we die we go to a sort of divine trade show, where all the possible gods have booths set up and we can stroll around as long as we want until we decide which one of them to go with.

The swag would be awesome, I bet.

Psi Baba · 7th May 2012, 10:05 AM

Originally Posted by aggle-rithm

The swag would be awesome, I bet.

Ha! That might be a good way to decide which one to go with. Any deity that is still giving away mouse pads or 1GB flash drives is clearly out of touch with their constituency.

Hokulele · 7th May 2012, 10:15 AM

Just make sure you pick up the 30-day trial DVD.

Jorghnassen · 7th May 2012, 10:35 AM

Originally Posted by Marquis de Carabas

Turns out, I'm just a Bayesian.

You don't have to be a Bayesian to realize that any (truth) value judgement you make is based on assumptions on which you may or may not put some prior probability (if it's strickly larger than 0 and strickly less than 1, then you're a Bayesian for sure).

As for the statement "absence of evidence isn't evidence of absence", well, that depends on the problem and the underlying assumptions. I currently have no evidence that my older brother is awake (or even alive) at the moment, I only have circumstancial evidence of the time of the day and his presupposed location. However, saying he must be asleep due to lack of evidence of his current wakefulness is not a more likely conclusion.

In the end, slogans and their converse are a poor excuses as critical thinking "dogma". Every claim should be critically examined, in the right context, carefully considering one's own prior assumptions, and not be taken at face value. That includes "absence of evidence isn't evidence of absence".

JoeBentley · 7th May 2012, 02:20 PM

Originally Posted by Skeptic Ginger

Slogans of wisdom tend to limit thinking.

And this is also undeniably true. I think of a lot of lay people through perfectly innocent motivations and a lot of Woo Slingers through perfecty not innocent motivations sometimes forget that just because scientific or rational principles can be distilled down to a nice pithy quote or rule of thumb that they actually exist as such things which they most certainly do not.

Simplifying things down to the layman's level isn't a bad thing per se, at worst it is a necessary evil, but when people start throwing them around like rocks in arguments without understanding the deeper meaning they represent they stop being simplifications and start being Thought Terminating Cliches.

In a slight hijack that's why I've almost begun to dislike Logical Fallacies. Not that I don't think they exist or that they don't represent real problems in thinking and arguing, they most certainly do, but more so they are so often used by people from all walks as a "Instead of arguing your point I'm just going to call it a bad name" tactic.

Gawdzilla · 8th May 2012, 05:02 AM

Hypothetical: We eventually discover everything about everything, with one exception. There is a rock that for some reason we can't look under. That is the only unknown spot in the Universe, the last place for God to be hiding. As a believer, would you then say that there is sufficient lack of evidence for concluding there is no God?

JoeBentley · 8th May 2012, 05:03 AM

Yep. They absolutely would.

HansMustermann · 8th May 2012, 05:07 AM

Actually, even if you could look under every single rock in the universe, the excuse that, see, God is outside the universe already exists.

6th May 2012, 08:36 PM	#1
derchin Critical Thinker Join Date: Apr 2012 Location: Here Posts: 325	"Absence of evidence isn't the evidence of absesence." Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it?

6th May 2012, 08:38 PM	#2
AdMan Philosopher Join Date: Feb 2010 Posts: 7,197	What's your point of view?
AdMan Philosopher Join Date: Feb 2010 Posts: 7,197	__________________ It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

6th May 2012, 08:48 PM	#3
slingblade Guest Join Date: Jul 2005 Posts: 23,642	Yes, let's please do hear what you make of it, first.
slingblade Guest Join Date: Jul 2005 Posts: 23,642

6th May 2012, 08:52 PM	#4
Kid Eager Illuminator Join Date: Nov 2010 Location: Australia Posts: 3,513	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? the need for a better spellchecker
	__________________ What do Narwhals, Magnets and Apollo 13 have in common? Think about it....

6th May 2012, 08:53 PM	#5
Brian-M Daydreamer Join Date: Jul 2008 Location: Downunder Posts: 4,285	Originally Posted by derchin What do you make of it? Absence of evidence isn't evidence of absence... except where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found. For example, if there have been persistent rumors of a yeti living in a local forest for decades, the fact that nobody's managed to provide evidence of a yeti living there isn't evidence that there isn't one there. But if you have hundreds of people systematically search the forest for evidence of a yeti and you find no evidence of a yeti in the forest, then this counts as evidence of absence of a yeti because you'd normally find some evidence of any large life forms living in the forest by that method. (Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.)
	__________________ "That is just what you feel, that isn't reality." - hamelekim Last edited by Brian-M; 6th May 2012 at 08:55 PM.

6th May 2012, 09:01 PM	#6
shadron Philosopher Join Date: Sep 2005 Location: Colorado Posts: 5,719	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? Johnny says: "This? Why, I can make a hat, or a brooch, or a pterodactyl..."

6th May 2012, 11:03 PM	#7
slingblade Guest Join Date: Jul 2005 Posts: 23,642	Originally Posted by shadron Johnny says: "This? Why, I can make a hat, or a brooch, or a pterodactyl..." Looks like I picked the wrong week to quit sniffing glue....
slingblade Guest Join Date: Jul 2005 Posts: 23,642

6th May 2012, 11:25 PM	#8
devnull Illuminator Join Date: Nov 2007 Location: Perth, Western Australia Posts: 4,533	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? It is, on the face of it, true. Unfortunately people take the next step, which is "and therefore, you should judge it a possibility".
	__________________ no, i don't think i need to read naturalistic literature more accurately, to be convinced its true. - Gibhor

6th May 2012, 11:57 PM	#9
Beelzebuddy Graduate Poster Join Date: Jun 2010 Posts: 1,721	Quote: Absence of evidence isn't evidence of absence. But it does waggle its eyebrows suggestively in that direction.

6th May 2012, 11:58 PM	#10
Dunstan Illuminator Join Date: Jan 2005 Location: Sunnyvale Trailer Park Posts: 4,292	What I make of it is: the null hypothesis wins. And, for the record, the null hypothesis is not "whatever the majority of people in my culture believe."

7th May 2012, 12:05 AM	#11
Marquis de Carabas Penultimate Amazing Join Date: Dec 2002 Location: vuori Posts: 27,106	I've always been mildly disturbed by the assertion. I'll buy "absence of evidence is not proof of absence", but it really is evidence. It just always seemed obvious to me that the saying was wrong. You get home, you call your wife's name and get no answer, you check all the rooms and don't see her. You have an absence of evidence that she is home, which is pretty good evidence that she is not home, no? True, she could be in the attic, or perhaps dodging just ahead of you from room to room, or hell, maybe you're secretly Reed Richards, but it's likely she just isn't there, based entirely on the absence of evidence that she is. Of course, I realize that's just sort of armchair reasoning, so it was with some delight a few years ago that it turned out I'm not the only one who feels this way, and others have expressed it far more rigorously than I have above. Turns out, I'm just a Bayesian. http://lesswrong.com/lw/ih/absence_o...ce_of_absence/ http://blog.sigfpe.com/2005/08/absen...idence-of.html
	__________________ Jesus ... wasn't he the bloke who turned fish into wine and made the lepers multiply? -KateHL Violence is more acceptable than incest. I have been told to keep this in mind.

7th May 2012, 01:06 AM	#12
Last of the Fraggles Illuminator Join Date: Nov 2006 Posts: 3,357	Absence of evidence quite clearly is evidence of absence. For example, if a murder was committed and you were accused of it then the fact that not a trace of you could be found at the scene would be provided as evidence that you weren't there and didn't do it. It may not be conclusive evidence, but it is evidence. The strength of which is largely dictated by what we would expect to find. Where it all gets silly is when the theist try to justify the absence of evidence. 'Of course he didn't leave any hair at the scene...he is able to shed all his hair at will and did so prior to entering the apartment.' 'Of course there are no footprints...he can levitate' 'Of course there is no DNA, he doesn't have any. In any case, he didn't need to enter the apartment. He could have killed him with the power of his mind' 'And how does that work?' 'Um..magic' 'Really?' 'You can't prove me wrong!!!!!!!!!!!!'

7th May 2012, 03:40 AM	#13
P.J. Denyer Graduate Poster Join Date: Aug 2008 Posts: 1,159	Originally Posted by Brian-M Absence of evidence isn't evidence of absence... except where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found. For example, if there have been persistent rumors of a yeti living in a local forest for decades, the fact that nobody's managed to provide evidence of a yeti living there isn't evidence that there isn't one there. But if you have hundreds of people systematically search the forest for evidence of a yeti and you find no evidence of a yeti in the forest, then this counts as evidence of absence of a yeti because you'd normally find some evidence of any large life forms living in the forest by that method. (Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.) This, absence of evidence may not be proof of absence, but it certainly can be evidence.

7th May 2012, 04:25 AM	#14
paiute Graduate Poster Join Date: Mar 2004 Location: Smack in the middle of a de Broglie wavelength. Posts: 1,140	Originally Posted by slingblade Looks like I picked the wrong week to quit sniffing glue.... Hey... knock a self a pro, Slick! That gray matter backlot perform us DOWN, I take TCB-in', man!
	__________________ A Novel and Efficient Synthesis of Cadaverine Organic chemistry, vengeful ghosts, and high explosives. What could possibly go wrong? Now free for download! http://www.scribd.com/doc/36568510/A...-of-Cadaverine

7th May 2012, 04:28 AM	#15
Darat Lackey Administrator / JREF Forum Liaison Join Date: Aug 2001 Location: South East, UK Posts: 64,803	Originally Posted by Brian-M ...snip... (Also worth remembering: absence of evidence of presence may not be evidence of absence, but absence of evidence of absence isn't evidence of presence either.) And if you can say that fives times fast then it is evidence of an absence of alcohol in your bloodstream!
	__________________ If it were all so simple! If only there were evil people somewhere insidiously committing evil deeds, and it were necessary only to separate them from the rest of us and destroy them. But the line dividing good and evil cuts through the heart of every human being. And who is willing to destroy a piece of his own heart? - Aleksandr Solzhenitsyn 1918-2008 Last edited by Darat; 7th May 2012 at 04:31 AM. Reason: a to e

7th May 2012, 04:35 AM	#16
Dancing David Penultimate Amazing Join Date: Mar 2003 Location: Central Illinois Posts: 34,729	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? The burden of proof lies on the positive claim.
	__________________ Hell, dynamiting fish in a barrel is more challenging. - Ladewig I suspect you are a sandwich, metaphorically speaking. -Donn And a shot rang out. Now Space is doing time... -Ben Burch You built the toilet - don't complain when people crap in it. _Kid Eager

7th May 2012, 04:46 AM	#17
HansMustermann Philosopher Join Date: Mar 2009 Posts: 9,850	I'd even quite happily leave it at "Absence of evidence isn't the evidence of absesence," but with the caveat that absence of evidence is also no reason to assume that something exists. Yes, there is always some tiny chance that we just didn't look in the one hidden cave where the world's only yeti lives, or we didn't stumble upon the exact spot where the dimensional portal to Santa's workshop is, but in the meantime there is also no rational reason to believe in them without any evidence that requires a yet or Santa to explain. Really, it's just Occam's Razor, and I think most people find it quite natural to apply it to anything except their pet woowoo. E.g., if I told someone that mom is Wonder Woman and has an invisible airplane, they would want some evidence before they believe either. "You can't disprove that she has an invisible plane" may be technically correct, but it also doesn't mean any rational person should believe it just because lack of evidence for such an invisible plane isn't evidence of absence of said plane. E.g., to take a sadly more real example, it was (and still is) impossible to prove that people don't fly on a broomstick to the witches' sabbath. You'd think that at least something like her husband testifying that she was at home in bed at the supposed night would be evidence that she didn't go anywhere, or that it was outside a major market and nobody there saw anyone flying or any window or door opening on that house, but they covered that aspect too: see, witches make themselves invisible, and leave a demonic double behind in bed. So really, the best you could have was a complete absence of evidence that such a sabbath exist or anyone goes there. But conversely, I think we can agree, that then there is no reason to assume that one does exist.

7th May 2012, 04:48 AM	#18
Beerina Sarcastic Conqueror of Notions Join Date: Mar 2004 Location: A floating island above the clouds Posts: 23,835	Originally Posted by Kid Eager Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? the need for a better spellchecker And an auto-capitalizer and punctuator.
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7th May 2012, 05:11 AM	#19
JoeBentley Self Employed Remittance Man Join Date: Nov 2009 Location: Norfolk, VA Posts: 1,767	Originally Posted by HansMustermann I'd even quite happily leave it at "Absence of evidence isn't the evidence of absesence," but with the caveat that absence of evidence is also no reason to assume that something exists. Exactly. "Absence of evidence isn't evidence of absence" only works in conjunction with the Null Hypothesis. Given the divide between what actually exists and what could possibly exist, working from possible and trying to find reasons why it doesn't exist is, at best, inefficient. But this is all rather academic. It's blatantly obvious when dealing with Theist and other Woo Slingers that it's not about evidence of absence versus absence of evidence. It's all about them coming up with various malarkey as to why they should just get to make crap up.
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7th May 2012, 05:14 AM	#20
Gawdzilla 121.92-meter mutant fire-breathing lizard-thingy Join Date: Nov 2009 Location: Northern St. Louis County, Missouri. Posts: 13,529	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? Absence of evidence is evidence of absence. Not absolute proof, but evidence.
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7th May 2012, 05:27 AM	#21
HansMustermann Philosopher Join Date: Mar 2009 Posts: 9,850	Originally Posted by JoeBentley Exactly. "Absence of evidence isn't evidence of absence" only works in conjunction with the Null Hypothesis. Given the divide between what actually exists and what could possibly exist, working from possible and trying to find reasons why it doesn't exist is, at best, inefficient. But this is all rather academic. It's blatantly obvious when dealing with Theist and other Woo Slingers that it's not about evidence of absence versus absence of evidence. It's all about them coming up with various malarkey as to why they should just get to make crap up. I don't think it's purely academic, actually. The infinite domain of what could possibly exist (especially if you throw in stuff like "outside the actual universe" or not subject to the laws of physics and such) is actually the main problem with Pascal's Wager, for example. I've actually done the exercise in a post of talking about what _a_ God could be like. Even taking the basic problems like suicide, murder, human sacrifice, rape, slavery, homosexuality, war in his/her name, etc, and a scale of basically: 1. Strongly condemns and punishes. 2. Is against, but it's not by itself reason to go to Hell. 3. Doesn't give a damn. 4. Is for, but it doesn't earn you a place among the chose by itself. 5. Explicitly commands and rewards. You get trillions of possible Gods, and you can't play it safe by just picking one because it hasn't been disproven. And by the way, there are actual religions on Earth where each of those can be a 1 or a 5. You'd think for example homosexuality can't be a 5, i.e., mandatory in any religion, but, really, there is IIRC one tribe where it actually is. What if their god is the right one? Just saying that it's not reason to assume something, still leaves the possibility to say, "yeah, but I'll play it safe and take a can of Bigfoot repellent anyway." It's only when you can make a point about that big domain of what could exist, and basically "what if you meet a chupacabra instead?", that shows why it's impossible and irrational to even try.

7th May 2012, 05:41 AM	#22
JoeBentley Self Employed Remittance Man Join Date: Nov 2009 Location: Norfolk, VA Posts: 1,767	And that. If something actually exists it tends to leave evidence for itself. The "Prove I'm not wrong!" angle puts people in the odd position of trying to come up with reasons where their pet Woo, which the obviously think is some grand universe changing idea, has absolutely no effect on the world which to me is rather self defeating.
	__________________ - Opinions require evidence and no before you ask defining something as "Something doesn't require evidence" doesn't count. - In extreme cases continuing to be wrong when you've been repeatedly proven to be wrong is a form of rudeness. - Major in philosophy. That way you can also ask people "why" they would like fries would that.

7th May 2012, 05:52 AM	#23
X Slide Rulez 4 Life Join Date: Oct 2007 Location: Launching the army, waiting for Hok to commit her forces (then the moles strike...) Posts: 4,082	I've said this before in the 9/11 Conspiracy Theory sub-forum: Absence of evidence is not evidence of absence, but absence of expected evidence can be. Also, you cannot disprove what I said.
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7th May 2012, 06:03 AM	#24
Foster Zygote Dental Floss Tycoon Join Date: Jun 2006 Location: Between the pit of man's fears and the summit of his knowledge Posts: 14,407	Originally Posted by derchin Or the "you can't prove/disprove X," argument. Used by some theists and atheists when defending their beliefs. What do you make of it? It is essentially correct. But it is important to remember that the inability to disprove something is not a sound reason to argue that it exists.
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7th May 2012, 06:22 AM	#25
bjornart Master Poster Join Date: Nov 2002 Posts: 2,398	I'd say it's only true when you haven't looked. Looking and not finding is evidence.
bjornart Master Poster Join Date: Nov 2002 Posts: 2,398	__________________ Well, I DON'T CARE WHAT YOU LIKE TO BELIEVE, GODDAMMIT! I DEAL IN THE FACTS! -Cecil Adams

7th May 2012, 06:39 AM	#26
JoeBentley Self Employed Remittance Man Join Date: Nov 2009 Location: Norfolk, VA Posts: 1,767	Originally Posted by bjornart I'd say it's only true when you haven't looked. Looking and not finding is evidence. And to take it one step further purposely not looking doesn't excuse Woo away either.
	__________________ - Opinions require evidence and no before you ask defining something as "Something doesn't require evidence" doesn't count. - In extreme cases continuing to be wrong when you've been repeatedly proven to be wrong is a form of rudeness. - Major in philosophy. That way you can also ask people "why" they would like fries would that.

7th May 2012, 06:47 AM	#27
HansMustermann Philosopher Join Date: Mar 2009 Posts: 9,850	TBH, I don't think it even warrants being made an explicit corollary. There simply is no rational reason to believe something in the absence of evidence. Exactly how and why one lacks evidence is IMHO just a tangent. Lacking evidence for refusing to even look, or lacking evidence because the dog ate the paper, or lacking evidence by virtue of being born in some stone-age tribe in the Amazonian woods, etc, all have the same important part: not having evidence.

7th May 2012, 06:52 AM	#28
JoeBentley Self Employed Remittance Man Join Date: Nov 2009 Location: Norfolk, VA Posts: 1,767	I don't consider holding opinions as to how the universe works without evidence to be any better then holding opinions as to how the universe works that are counter to the evidence. Ideas are valid based on positive evidence for them. Lack of evidence against them is really just a double check, a fail safe, a checking your work kinda thing.
	__________________ - Opinions require evidence and no before you ask defining something as "Something doesn't require evidence" doesn't count. - In extreme cases continuing to be wrong when you've been repeatedly proven to be wrong is a form of rudeness. - Major in philosophy. That way you can also ask people "why" they would like fries would that.

7th May 2012, 07:06 AM	#29
Foster Zygote Dental Floss Tycoon Join Date: Jun 2006 Location: Between the pit of man's fears and the summit of his knowledge Posts: 14,407	Originally Posted by bjornart I'd say it's only true when you haven't looked. Looking and not finding is evidence. I agree. But as often put forth by theists, it becomes an epistemological issue of their god or gods being somewhere in the universe where we can't observe. To restate one of my favorite analogies regarding a '67 Dodge Dart orbiting a star in the Andromeda galaxy: Just because we can't survey every star in M31 to check for the presence of the Dodge Dart, it doesn't follow that its presence is any more likely.
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7th May 2012, 08:32 AM	#30
Mick Houlahan Thinker Join Date: Jan 2006 Location: Lion's Pride Inn, Goldshire Posts: 215	Originally Posted by slingblade Looks like I picked the wrong week to quit sniffing glue.... Surely you can't be serious.

7th May 2012, 08:53 AM	#31
Skeptic Ginger formerly skeptigirl Join Date: Feb 2005 Location: Shifting through paradigms Posts: 40,628	Slogans of wisdom tend to limit thinking. "Absence of evidence isn't evidence of absence" leads people not to think of things like the exception noted where there is an absence of evidence in circumstances where evidence would reasonably be expected to be found. In addition, the slogan leads people to assume the false conclusion that said absence is evidence the thing does exist. This slogan is most often use to justify god beliefs. "Absence of evidence isn't evidence of absence" was appropriate when Sagan used to to refer to the current lack of evidence of ET life somewhere out there in the Universe. But it is not equal when the slogan is applied to god beliefs. We have evidence of some life in the Universe, us. There is no evidence of gods thus the slogan cannot be applied in the same way. Two similar slogans that cause 'no-think' are, "the plural of anecdote is not evidence" and "anecdotes are not evidence". These are even more problematic than the absence of evidence slogan. First, anecdotes are evidence. What is typically being referred to by the slogan is the conclusion people draw from the anecdote, not the anecdote. Or someone repeats a questionable observation as evidence for something. All observations are not equal. Some observers and observations are more reliable than others. For example, a trained observer or an eye witness to a crime where the perpetrator is known to the witness are going to result in more reliable 'anecdotes' than an untrained observer or a witness to a crime committed by a stranger respectively. Adding controls to a collection of anecdotes or collecting the anecdotes systematically can also result in a plural of anecdote that is indeed evidence. If we are going to use these slogans we should understand them. But when they are passed on as memes, quite often they end up beng misapplied and leading critical thinkers down cul-de-sacs instead of down the connecting streets.
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7th May 2012, 09:32 AM	#32
aggle-rithm Ardent Formulist Join Date: Jun 2005 Location: Austin, TX Posts: 14,156	Originally Posted by HansMustermann You get trillions of possible Gods, and you can't play it safe by just picking one because it hasn't been disproven. It occurs to me that, maybe when we die we go to a sort of divine trade show, where all the possible gods have booths set up and we can stroll around as long as we want until we decide which one of them to go with. Better be careful, though...the afterlife may not be as advertised, and we'll be stuck with it for quite some time.
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7th May 2012, 09:33 AM	#33
aggle-rithm Ardent Formulist Join Date: Jun 2005 Location: Austin, TX Posts: 14,156	Originally Posted by aggle-rithm It occurs to me that, maybe when we die we go to a sort of divine trade show, where all the possible gods have booths set up and we can stroll around as long as we want until we decide which one of them to go with. The swag would be awesome, I bet.
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7th May 2012, 10:05 AM	#34
Psi Baba Homo Skepticalis Join Date: Aug 2001 Location: Occupying my barstool Posts: 3,183	Originally Posted by aggle-rithm The swag would be awesome, I bet. Ha! That might be a good way to decide which one to go with. Any deity that is still giving away mouse pads or 1GB flash drives is clearly out of touch with their constituency.
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7th May 2012, 10:15 AM	#35
Hokulele Official Nemesis Join Date: Feb 2007 Location: Trying to decide whether to set defenses against an army, or against mole rats. Posts: 27,274	Just make sure you pick up the 30-day trial DVD.
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