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thoughtomator>It is logically impossible to prove a negative; challenging someone to do so either shows a serious deficiency in basic reasoning skills or demonstrates an intent to debate dishonestly. I'll give you the benefit of the doubt, but you still need to take Logic 101.

and

Protect the Bill of Rights>Back in my day the first lesson learned in geometry was:

It is impossiible to prove a negative.

It was pounded into us over & over again

[...]Dumbing down America has done wonders for the media as it helps them lead the masses.

No offense, but it sounds like the dumbing down started before you two reached 10th grade or Logic 101. ;-)

While I'm being a wisecracker, should I point out that "You can't prove a negative" is inherently an unsupportable statement...since it's a negative itself!

The fact is, many negatives are easily prove via contradiction or other means. For example, we can prove that there are no rational numbers equal to the square root of 2.

Couldn't the geometry teacher figure out how to prove that a circle was not a square?

What Logic 101 instructor wouldn't know

If A, then B.
Not B.
Therefore, not A.

But most importantly, it would be an extremely unwise policy to require "proof" before action. Funny, many people who didn't require proof of WMD in Iraq now ask for it regarding climate change. "Proving" that private retirement savings wouldn't do worse than Social Security returns shouldn't be a requirement before supporting them. Anyone who leaves his house has made conclusions without proof.

One thing I heartily agree with, though, is the handle of "Protect the Bill of Rights". :-)

Try proving "Not B" in the absence of a reliable "If A then B". That is what he asked me to do (identify the A and B of this discussion). To do that one must accept "If A then B". But how do you prove "Not B" if you cannot say for certain what the relationship is between A and B, or indeed if there is any such relationship at all? It can't be done.

The point is that proving human activity is not responsible for global warming is a in-practice impossible task, as you could not in one lifetime analyze every human action and derive its ultimate effects on the global temperature.

Thus, someone saying global warming is caused by human activity challenging someone else to prove it is not so is asking the impossible. What can be proven is that the information we have to date is not sufficient to prove that global warming is caused by human activity to any degree. And given the total absence of evidence that logically leads to such a conclusion, the positive statement of the insufficiency of global warming theories is proven with the evidence I provided above.

Far from being dumbed down, we were taught principles which have stayed with us.

(You can't prove a negative was my expression, not the teachers--didn't realizew how I contradicted myself on that one DUH!)

To simplify: (not geometry, but same principle)
Prove you are not 75 years old.
The easy way, of course is pull out the license and say "I was born in 1954 which makes me 50" I just proved I was not 75 years old.

In geometry class I did not prove I was not 75 years old.
I proved I was greater than or less than 75 years old.

I was not dumbed down by any stretch of the imagination. Looking back, I realize it was the logical process we were being taught.

Your example:

If A, then B.
Not B.
Therefore, not A.

What is not in your problem is how you arrived at "not B"

You proved C.

I am a nurse and have done many, many dosage calculations in my career. Instead of being dumbed down, I always say a prayer of "Thanks" to the excellent teachers I had in algebra and geometry when faced with a complicated dosage calculation.

I learned how to set the problem up, how to solve it, & how to check my answer. Taking shortcuts instead of using a logical process would have made for alot of medication errors. (Okay, maybe I could call the pharmacy, but they do not allow you to call the pharmacy when taking an exam.)