TerryTryon

We positive atheists are often chided for our confidence with the catch phrase, “The absence of evidence is not evidence of absence,” or in stronger words, “You cannot prove a negative.” To go beyond the aphorism, what, if anything, counts as evidence of absence? In other words when someone challenges our atheism, is the only defense we can muster is a lecture on who bears the burden of proof?

In one of his books, Antony Flew describes a thought experiment I have come to call the Allegory of the Boulder. Suppose that a guest in your house suddenly declares that that there is an enormous boulder in the middle of your living room. You reply, “No, there isn’t. I am looking at the space, and there is simply nothing there.”

“That’s because it is invisible.”

“But if I examine the place where you say the boulder lies, the pile of the carpet is not crushed as it would be if something as massive as a boulder lay there.”

“It is also without mass.”

“If I walk across the place where you claim the rock lies, I do not stub my toes.”

“The boulder is intangible.”

At this point, I would observe that the meaning of the word “boulder” entails certain attributes, among which are mass, visibility, and tangibility. If there is anything extraordinary in the space referred to, it certainly cannot be referred to as a boulder.

I believe I have thereby demonstrated evidence of absence. I have also proven a negative.
The word god, as used in monotheism, implies some very strong claims about the how nature operates, and the structure of the universe. If these conditions are not met, am I justified in saying that the monotheistic god does not exist? Am I permitted to insist that any concept of god must carry a set of coherent attributes, which may not be refashioned in an ad hoc manner according to the direction of the debate? Is there such a thing as “evidence of absence”?

Oxymoron

An interesting question. The example that comes to mind for me is the search for extraterrestrial life. Clearly, the fact that we haven't found any yet cannot be held as evidence that there aren't any other sentient beings of high enough tech level out there.

The difference between that and your boulder example is that the boulder test has failed whilst the ET test has returned "no result". I think the "absence of evidence" mantra only applies to the latter.

But then it's midnight in the UK and I've had a couple of margaritas, so I could be wrong

Synaesthesia

I don't think the process of concluding that a proposed entity is scientifically implausible is much different from concluding that it's plausible.

Fiach

The boulder which you cannot see, doesn't compress the carpet, and you can't stub your toe on it is a good example of something that shows lack of evidence is indeed evidence of absence. It is so because you have defined the boulder has having certain properties, hardness, mass, and visibility.

God is definied as invisible, inaudible, intangible, non-natural, immaterial, and even implausible. In short its properties are that of seeming to not-exist.

Therefore, absense of evidence is meaningless for an entitity that's essence is to apppear non-existent and demonstate no evidence of existence.

Fiach

Fiach

[ November 30, 2002: Message edited by: Fiach ]</p>

Undercurrent

Except for the "knocking on the door to your heart despirately trying to get your attention so you will believe in him" part that many theists add to the definition in other contexts.

m.

Family Man

This is hardly my field, but I personally think that the "evidence of absence" defense gets used in places that are inappropriate.

To me, if a claim is made an important method of assessing the truth of the claim is whether any consequences of the claim are present. For example, if I'm sitting by a lake and someone tells me they just threw a stone in the lake, I'll look for the ripples. If I don't see them, I know the claim is false. There may be absence of evidence, but the absence of observed consequences are telling.

I think that there are claims for God out there -- such as he being omnipotent, omniscience, and omnibenevolent -- that imply certain consequences that are indeed missing. These are often our most powerful arguments against the existence of any God.

Jobar

Carl Sagan's version of this is the invisible floating dragon in his garage, which breathes invisible heatless flame. (From "Demon Haunted World" I think.)

For something to exist, we need to define it. In the case of ETIs, we define it to be a source of structured transmissions from outside our solar system; since we have detected no source within a few hundred light years of Sol, we can not say that *no* ETIs exist, because the universe is far vaster than the miniscule area we have searched.

When the entity being discussed is God, the lack of any agreed-upon definition allows us to prove nonexistence, IMO. We can certainly require anyone claiming proof to define God in a way which allows proof or disproof. If no such definition is forthcoming, we are quite justified in telling the theist his claims are nonsense.

TerryTryon

In the case of Flew's boulder, there are clearly defined parameters. We know what a boulder is, and what we are willing to identify as a boulder. We know the space which the boulder is supposed to occupy. Because everything is so clearly defined, we know the claim is false.

This is not true with contact with alien intelligences. We do not know where in the universe they may be. We do not know what form they would take or if we would recognize them as lifeforms at all. Anything we surmise about alien life would be, at this point, bald, unsubstaniated speculation.

However true the situation with ET's may apply to to a broad definition of god, there are certain claims about the God of Abraham, which are universally or nearly universally accepted, namely that he is the creator of the earth (if not the universe), that he has a special interest in mankind, and that he is responsible, in some way, in meting out justice in a universal manner. All these claims entail a certain structure in ourselves and in our surroundings. This inherent structure is testable; therefore, the existence of this particular god is indirectly testable.

If the god of Abraham exists, certain things must be true of the world. If this god does not exist, these things will not obtain.

Perhaps our knowledge at this time is insufficient to identify how the traits of god impact on the universe. And how to test whether the world we inhabit exhibits this influence of god is controversal. But, in principle, the existence of this narrow concept of god is testable.

Zadok001

I believe it is fully impossible to disprove the existance of a deity. Regardless of how much evidence is lacking (sense not to the making I am), you can never prove the non-existance of an entity with 'infinite' power. This entity would obviously be capable of obscuring himself, and perhaps even his actions.

We assume that if God ran around saving people from certain death and being an all-around omnibenevolent entity that we would see a result. However, this God would also be perfectly capable of 'masking' his actions so we would never uncover them, thereby masking the very evidence we need to determine his existance or lack thereof.

That's why, IMHO, religon is so powerful - An all-powerful entity isn't disprovable. Your boulder, perhaps. It has known characteristics. It also has no intelligence, and certainly not infinite intelligence. But with God...

"God is outside your window."

"I can't see him."

"He's invisible."

“But if I examine the place where you say God is, the grass is not crushed as it would be if something as massive as God there.”

"He is also without mass."

“If I walk across the place where you claim God is, I do not stub my toes.”

"God is intangible."

See how that argument now appears at least slightly rational?