Terrapin Station wrote:Absence of evidence is ALWAYS evidence of absence.
RJG wrote:Logically, this is self-contradictory. The absence of X can NEVER be X. [~X=X is logically impossible]. Therefore, the absence of evidence can NEVER be evidence (of anything).
Leontiskos wrote:I think your larger position is tenable, but this argument is mistaken. You are misinterpreting the meaning of what is being said. This is what Consul has said:
Firstly, I'm not responding to Consul, I'm responding to Terrapin. Secondly, the statement ---
"the absence-of-evidence is evidence-of-absence" is an obvious
logical contradiction, plain and simple. [~X = X]. (...I'm somewhat shocked that you don't grasp this simple logical truth
)
Leontiskos wrote:This is what Consul has said:
"Absence of evidence for milk is evidence for absence of milk."
Phrased differently:
"Absence of evidence for milk is evidence for not-milk."
It does not matter how this is phrased, it is still a logical contradiction. It is committing an appeal-to-ignorance fallacy; the "absence-of-evidence" (of
anything) is NOT evidence-of-absence (for
anything, ..or for
anything else, ...or for
not-anything, ...or for
not-anything else). No evidence is no evidence for anything. For example:
-- If you have no evidence of X, then this does NOT mean that you have evidence of not-X.
-- If you have no-evidence of milk, this does NOT mean that you have evidence of not-milk.
-- If you have no-evidence of UFO's, then this does NOT mean that you have evidence for the non-existence of UFO's.
-- If you have no-evidence of God, then this does NOT mean that you have evidence for the non-existence of God.
Leontiskos wrote:What you are failing to see is that absence of evidence for one thing can be presence of evidence for a different thing.
Not possible! You can't get evidence from non-evidence. You can't get evidence of milk or no-milk from no evidence (of anything!). You can't get evidence of UFO's or no-UFO's from no evidence (of anything!).
Terrapin Station wrote:For example, if we're wondering if our car keys are in the jacket we wore yesterday, we'd check the pockets, and if our car keys are not there, that absence of evidence is clearly evidence of absence of our car keys being in that jacket.
RJG wrote:There is NO "absence of evidence" here, there is only "evidence of absence".
Since you checked your pockets for your keys, you ONLY have the "evidence of the absence" of your keys. But if you did not check your pockets for your keys (or did nothing but wonder if your keys were there), then this would be "absence of evidence".
Either you have evidence or you don't. - If you have no evidence, then you certainly cannot have evidence! ~X=X is logically impossible!
Leontiskos wrote:...and an empty pocket is incompatible with a coin. Both of these are true. You are misrepresenting the claim.
Nonsense. I'm not misrepresenting anything. If you look in your pocket and see that it is empty then this is "evidence of absence". So now tell me where/what is the "absence-of-evidence"?
You either look in your pocket and
have evidence (of a coin or of no-coin) or you
don't have evidence (of anything!). You either have evidence (one way or the other) or you don't! Period. It is either X or ~X, but not both!
**************
Steve3007 wrote:"Absence of evidence for milk is evidence for absence of milk."
is not contradicting himself because in that sentence the first evidence is "for milk" and the second is "for absence of milk". So they're evidence for/of two different things. Hence, as you've said, the simple X substitution doesn't work.
Consul is still contradicting himself with this phrase even though milk and not milk are two different things.
Claiming that UFO's (or milk in the fridge) don't exist because we have
no evidence (of their existence or non-existence) is logically invalid and unsound (aka "non-sensical").