[albert (OP)]

A challenge issued by a creationist on a forum I frequent - I wasn't quite sure how to respond....

"I challenge YOU to PROVE the existance of "LIGHT" to a BLIND man, using ONLY scientific methodology!".

We could perform an experiment to show heat radiation in the IR spectrum - a blind person could percieve that. Come on guys give me some meat to throw back at him....


Albert

[paul.fr]

Albert, do Artificial retinas count?

[another_someone]

The same way you would prove radio transmission, or any other transmission of information that is not directly available to our senses - you prove that information has been transmitted through a medium where all other means of information transmission have been excluded.

You place the blind man in a room, surrounded by double glazed glass walls, which are impermeable to sound, heat, smell, etc.  You have observers outside of the glass room writting down what they see the blind man doing in the room, and sending those messages back to him.

This will prove that there must be some information that the blind man is incapable of detecting that is passing through the glass to the sighted people.  Whether you call the medium of this information light, or you give it another name, is not significant, all that matters is that there is something (which we might arbitrarily call light) that is beyond the senses of the blind man, but that gives a consistently reliable transmission of information.

You could do the same thing in another way.  Have a pack of cards with images on one side, and braille on the back.  Ensure that the sighted person cannot touch the cards, and that the cards are identical except for the image (it may be as simple as having different colours on the cards).  Show the sighted man the cards, but do not let him touch the cards.  The blind man then reads the braille (which the sighted man has no access to).  If the sighted man correctly identifies each card (which the blind man can verify with the braille), then it follows that there must be some information (again, we shall arbitrarily call it reflected light) that is being sent from the cards to the sighted man that is not detectable to the blind man.

[another_someone]

Let me add another comparion to this question.

We know that dogs can hear sounds human cannot hear, and we know that dogs can smell things humans are unable to smell.  We do not need to directly hear the sounds ourselves to know they are there, or smell the smells ourselves to know they are there, we just observe the dogs, and can see that they are consistently reacting to cues that are unavailable to us, and that subsequent investigation demonstrates that the dogs actions were not arbitrary but consistent with there being a reliable source of information that the dog could sense even if we could not sense it.

[daveshorts]

If everyone in the world were blind - possibly the question - you could build some sort of electronic sensor that was sensitive to light and changed the sound it made with the light incident upon it. You then point it at things and listen, try putting things in the way etc etc. and build up a picture of it's properties.

Obviously it is impossible to proove anything with the scientific methodology, all you can do is come up with a best theory that is consistent with the known evidence.

[Bored chemist]

This remnds me of a tale I saw, I think it was an end of article filler in Readers Digest.
A bunch of peole are at a dinner party. One person, an army officer I think says "I have never seen any scientific proof of the existence of God"
The Priest retorts that he has never seen any theological proof of the existence of atoms.

In the version I read, this was viewed as "putting the officer back in his place with a with comeback".
As I see it, it seems to show that theology never proves anything.
To be fair, science (other than maths) never proves anything- that's not it's job. All science can ever do is Disprove theories.
If someone asks you questions like "I challenge YOU to PROVE the existance of "LIGHT" to a BLIND man, using ONLY scientific methodology!". you need to explain that they simply have not understood science.

The fact that you could get a blind man to accept that there is such a thing as light is not strictly scientific proof. OK you could get someone to tell him what he's doing as Another Someone sugests, but that is just as valid a proof of mindreading as it is of the existence of light.

[another_someone]

The fact that you could get a blind man to accept that there is such a thing as light is not strictly scientific proof. OK you could get someone to tell him what he's doing as Another Someone sugests, but that is just as valid a proof of mindreading as it is of the existence of light.

What I said is that the experiment I proposed would demonstrate that there was a medium of communication which was beyond the competence of the blind man, and that we can arbitrarily label this medium 'light'.  I would still say that is true.

What I was careful not to say was anything about the properties of this thing we call light.  I spoke not of photons or waves, only that information is transmitted by something, and we can apply a label to that something.

It could be used as a proof of 'mindreading' - you will have to explain to me what the properties of this 'mindreading' are, but if you simply want to label the phenomenon we have observed as mindreading, you may do so (it is after all only a label).

Where you might have a point is if you were to suggest that one cannot rule out arbitrary coincidence, that all the experiment shows is that there are a series of individual events that are highly improbable (but never impossible) to be attributed to chance, and thus if we assume the absence of such an improbable chance, then we may associate those events with some consistent phenomenon, and we may then attach a name to that phenomenon.

What science tries to do is to identify patterns of events that it considers to be too improbable to be attributed to mere chance, to label those patterns, and then to build models that will extrapolate those patterns in order to predict future events.  It is in the area of building models and future prediction that we get into the problem that nothing is ever proven, only disproven.  In that respect, creating models of light that make assumptions about energy, waves, relativity, etc., is where you get into the arena of being unable to prove any of it (and in fact there is substantial likelihood that at some time in the future at least one of those models will be disproven or drastically modified), but that is not to say that the collection of related events that we call light is itself ever likely to be disproven.

[Bored chemist]

In the style of many theological arguments.
The properties of "mindreading" are those properties that, in the experiment detailed above, would make it indistinguishable from light but in some other ways (only revealed to the chosen ones) differ.
Anyway, as we agreed, the real point is that science never really proves anything- it just disproves as many alternatives as it can.

Since the properties of "God", like those of mindreading, can be changed arbitrarily, "God" can never be disproved. Even where the properties of "God" are logically impossible, logic is deemed to be at fault.
For example "God" is, more or less by definition, omnipotent- He can do anything; that's what makes Him "God".
OK, can He set Himself a task which He cannot achieve?
If not then He's clearly not omnipotent. If He can set such a task then, since He can't achieve it He's not omnipotent. Omnipotence is a paradox, but that doesn't bother some people.

[albert (OP)]

I've just read a fantastic NY Times articles about hard-wired theism.

We're all belief fridge-magnets - compelled to stick to a belief in 'something' mystical.

http://www.nytimes.com/2007/03/04/magazine/04evolution.t.html?pagewanted=1&ei=5088&en=a43cfb7b24423cc6&ex=1330664400&partner=rssnyt&emc=rss [nofollow]

[another_someone]

In the style of many theological arguments.
The properties of "mindreading" are those properties that, in the experiment detailed above, would make it indistinguishable from light but in some other ways (only revealed to the chosen ones) differ.
Anyway, as we agreed, the real point is that science never really proves anything- it just disproves as many alternatives as it can.

Since the properties of "God", like those of mindreading, can be changed arbitrarily, "God" can never be disproved. Even where the properties of "God" are logically impossible, logic is deemed to be at fault.
For example "God" is, more or less by definition, omnipotent- He can do anything; that's what makes Him "God".
OK, can He set Himself a task which He cannot achieve?
If not then He's clearly not omnipotent. If He can set such a task then, since He can't achieve it He's not omnipotent. Omnipotence is a paradox, but that doesn't bother some people.

The question was only concerning how you can prove the existence of light.  I do not dispute your arguments about the greater vagaries of proving God, but if the question had been about that, I would have moved the discussion out of the science arena and into something like "It can't be true" (although we already have more than enough of the like already there).