hinduwoman

Yes, but only because everyone agrees on what the essential characteristics of a giraffe or female are. If there is disagreement on this then you cannot prove it to everyone's satisfaction.
Look at transversites for example. Are they male or female? In India they insist they are female though biologically they are male, while the classical Hindu theory is they are third sex.

That is why in respect to God atheists insist that theists prove there is a God; it is no use proving that Shiva does not exist only to have the theist say that Jesus did.

Negatives depend on some positive definitions.

Doubting Didymus

A magic hippogriff is a hippogriff that can do magic. 'Magic' itself being an undetectable means by which actions (not defined) can be performed.

'Unrestricted' is better defined by reference to a restricted negative. 'there is no elephant in the room' is a restricted negative. It is restricted by the boundaries of the room. the unrestricted statement by my definiton is 'there is no magic elephant in the room'. You can not prove it, because the elephant overcomes any restrictions and boundaries by magic. It can, however, be DISproven, because although the elephant is 'magic', there is no parameter of its existence that says it can not demonstrate itself.

The point is: any negative that can be proven is guaranteed to be a restricted negative. It is obvious that you need some boundary which you can explore to the limits and report that the negative is confirmed. "no elephant in the room" is provable by searching the room. "no hippogriffs exist" is theoretically provable by searching the universe. "no magic hippogriffs exist" has no restricting parameters at all. You could search the whole universe and apply any logic you like, but as the things capacities are not restricted it can always be said that it simply used magic. Note that any attempts to describe the limitations of magic would be restricting the negative.

Clutch

hinduwoman,

Well said.

Didymus,
So it's just the "undetectability by definition" case again, which (assuming its conceptual coherence) fails to support any positive/negative distinction, as I've already noted.
So it's just the difference between definite/indefinite search domains again, which I've already treated.

Sorry, I just don't see where you've given a case that (a) is well-defined, (b) bears out some difference between positive and negative claims, and (c) does not permit the accretion of genuine evidence, modulo the problem of induction. From what I've seen, your comments about magic seem ill-suited to serve as the basis of a claim about the principled unprovability of negated existence claims.

Doubting Didymus

Not really, you said that if the statement is a well formed empirical conjecture then we can make statements about its probability. That is true, but this simply means that unrestricted negative statements are not well formed empirical conjectures. I say again: when you define the limits of the hippogriff, your statement is restricted. When you do not define the limits of the hippogriff, chances are that your statement is unrestricted.

I thought I dealt with the difference between positive and negative claims in my last post. undefined hippogriffs, for example, might be able to reveal themselves, or be otherwise detected. Thus, their existence can be demonstrated, but not disproven.

I've wanted to avoid this one, as it is rather value laden, but a mighty fine example of a case that satisfies all three of your above criteria is everyones favourite mate, God.

The statement 'god does not exist' is an unrestricted negative that can not be proven. God is generally described as being exempt from all laws of nature, and thus all known cases. He is thus a perfect example of the problem of induction, as his very definition puts him as far as possible from all known cases. His parameters are also unrestricted, no evidence counts as disproof.

Thus: the proposition 'there is no god' is an unrestricted negative that cannot be proven. However, the difference from the positive form is that it can be disproven. There are any number of observable states that may count as proof of god. It is precisely this case that most people refer to as being unable to prove a negative, due to the fairly common theist argument, 'prove that god does not exist'.

Note that this applies only to one common conception of god: the incomprehensible spirit being version whose plan and motives are beyond our knowing. There are forms of god that are restricted, such as the conception where he sits on the firmament.

Clutch

No. If you give the identifying criteria by which they could be revealed, you give properties by which their non-existence can also be evidentially weighed.

This all just shows why principles of inference are not defined in terms of magic.

Keith Russell

Greetings:

Something 'undefined' could exist (if it's possible--not undefined contradictory concept such as 'God' or 'square-circles) but it is not rational for someone to believe that an 'undefined' entity exists.

Rational belief depends on specific, independently verifiable evidence. Evidence cannot support something that is 'undefined'; the 'undefined' is--by definition--also unspecific.

Keith.

Clutch

Keith, there's no "could" about it -- kangaroos, platypuses, and continental drift all existed before they were defined. We're talking about evidence for specific existence claims, though.

'least, I am.

Keith Russell

Clutch:

Yes, you are right, lots of things--in fact everything that exists existed before it was defined.

Sad but true that this point occasionally needs to be stated yet again...

Keith.

Doubting Didymus

How so? a hippogriff that could remain evidentially hidden, yet could also choose to become evidentially revealed could be proven by such a hippogriff revealing itself. How does this help someone trying to prove that no such being exists?

To prove such a hippogriff: produce the hippogriff, and it is proven.

To prove that there are no such hippogriifs: What?

spelling edit.

[ September 11, 2002: Message edited by: Doubting Didymus ]</p>

Keith Russell

Greetings:

Rational beliefs are based only on evidence.

If there is no evidence of hippogriffs, it is not rational to believe they exist.

As long as the concept 'hippogriff' doesn't contradict any of the known facts of reality (as the concept 'God' does), then it is rational to believe that hippogriffs are possible, sans evidence.

But, if there is no evidence such creatures exist, it is not rational to believe that they exist.

Keith.