Proving a negative

[pseudobrit]

Russert: "The New Yorker" magazine revisited a subject that we talked about in December, and they insist that in November, and this is the article, "In interviews, American intelligence officials and high-ranking military officers said that Pakistanis were indeed flown to safety in a series of nighttime airlifts that were approved by the Bush administration. The Americans also said that what was supposed to be a limited evacuation apparently slipped out of control, and, in an unintended consequence, an unknown number of Taliban and Al Qaeda fighters managed to join in the exodus."

The point being in November, Pakistan was able to airlift people out of Afghanistan. Did that happen?

Rumsfeld: I do not believe it happened. I can't prove a negative, but our people have checked to the extent that it is possible to check. We have had enormous numbers of aircraft and intelligence sensors in various ways watching that area. No one that I know connected with the United States in any way saw any such thing as a major air exodus out of Afghanistan into Pakistan.

I have read these stories, I've heard these stories. I've never been able to run them down. No one has ever been able to run them down and prove them, and I doubt them. I think they're not true.

Emphasis mine.

Interesting that Rummy, when it's Pakistan, now thinks a negative can't be proved. Only a year ago he demanded that Saddam prove one.

Talk about a flip-flop. We've given a pass to Pakistan even though they've admitted to selling nuclear technology.

link (http://www.defenselink.mil/news/Jan2002/t01202002_t0120sd.html)

[skunk]

I think that unless Pakistan PROVES they didn't do it, you should invade. Self-defence if you ask me.
Oh, and if the Administration was complicit, invade yourselves, too....(and leave the rest of us alone).

[IJ Reilly]

I don't understand why people so often say they can't "prove a negative." Of course they can, and it's done in science routinely. It's called a "null hypothesis."

[toontra]

I don't understand why people so often say they can't "prove a negative." Of course they can, and it's done in science routinely. It's called a "null hypothesis."

"Null hypothesis" sounds like Bush's foreign policy!

[zimv20]

this is the first i've heard of a major news outlet picking up greg palast's assertion (he wrote the New Yorker article). i'm glad someone's bringing it up, 'cuz it's an utter and complete outrage, if true.

[skunk]

this is the first i've heard of a major news outlet picking up greg palast's assertion (he wrote the New Yorker article). i'm glad someone's bringing it up, 'cuz it's an utter and complete outrage, if true.
Outrage, schmoutrage. I'm in danger of getting "Outrage Fatigue"....
But seriously, how long can these guys keep this crap up? :mad:

[bryanc]

I don't understand why people so often say they can't "prove a negative." Of course they can, and it's done in science routinely. It's called a "null hypothesis."

Um, not quite...in science, we don't prove hypotheses. We *falsify* hypotheses. What you have to do in order to support an hypothesis is to falsify the null hypothesis.

However, it is sometimes possible to prove a negative. For example, for organisms whose genome has been sequenced, we can say such-and-such a sequence does not occur in the genome (i.e., we can demonstrate the negative, that mice don't have a CECR-1 gene). Still, unless you know everything about a given realm of possibilities, it is very rare that one can prove a negative using empirical evidence.

Hope that clarifies.

Cheers

[mactastic]

I was wondering about that too, my understanding of the null hypothesis (albeit limited) was that it is not so much proving a negative as it is proving that statistical deviations for a given group of samples are or are not the result of random chance.

[skunk]

I was wondering about that too

Well, I'm glad we got THAT cleared up! :)

[IJ Reilly]

Um, not quite...in science, we don't prove hypotheses. We *falsify* hypotheses. What you have to do in order to support an hypothesis is to falsify the null hypothesis.

However, it is sometimes possible to prove a negative. For example, for organisms whose genome has been sequenced, we can say such-and-such a sequence does not occur in the genome (i.e., we can demonstrate the negative, that mice don't have a CECR-1 gene). Still, unless you know everything about a given realm of possibilities, it is very rare that one can prove a negative using empirical evidence.

Rare perhaps, but it is an established principle of deductive reasoning to disprove explanations of a phenomenon in order to arrive at an explanation that might be the true cause.

[zimv20]

more to the point, it's extremely difficult to prove that you are not in possession of something, and prove that you never said a certain phrase.

scientifically, one must search all space and review all speech ever uttered by the person, respectively. the burden of proof falls on the accuser.

in this case, greg palast provided empirical evidence and eyewitness accounts that the pakistanis were "allowed" to evacuate bin laden et. al. i'd expect rumsfeld to discount that evidence, rather than throw up his hands and say it's not possible.

that he does so lends support to palast's claims, imo

[IJ Reilly]

more to the point, it's extremely difficult to prove that you are not in possession of something, and prove that you never said a certain phrase.

I don't think this is an example of trying to prove a negative so much as it might be trying to prove the impossible or the absurd; i.e., you might find it equally difficult to prove that you did utter a certain phrase.

[zimv20]

I don't think this is an example of trying to prove a negative so much as it might be trying to prove the impossible or the absurd;
as was mentioned, trying to get saddam to prove he had no WMD

you might find it equally difficult to prove that you did utter a certain phrase.
could be, yeah, unless it's been published. or as i am often able to do w/ my pot-smoking friends, is get them to remember something i said by reminding them of where we were and what we were doing, or even what we were talking about to lead up to it. always makes me laugh to see that expression of recognition.

of course, it's wholly different when the party is trying really hard to *not* remember...

[mactastic]

It's like the cops or prosecutor asking you to prove you didn't commit the crime they are charging you with. In that situation an absence of evidence either way will convict you. Your odds of conviction go up if the cops are cherry-picking from what evidence does exist, or outright lying.

Somehow I don't think Dubya, or the right wing, would find it a fair proposition to prove they didn't lie to the country about the war intelligence. I'm sure their response would be that someone needs to prove their guilt instead.