Y’know, I’ve always thought… people seem to say that you can’t prove a negative, and they say it an awful lot, but what gets me is that they say it with such certainty. How are they so sure? I mean, to say that you probably can’t prove a negative, or that it would appear that proving a negative is impractical; that would be fine. It just seems that going any further than that might be tricky to back up, logically speaking.
~ Isaac
The way I was taught it, you couldn’t prove a scientific theory, only disprove it because the proof was esentially proving a negative (this theory will not fail).
This is because science is an inductive system rather than a deductive system. ie: you can’t prove the theory of gravity because you would need to prove that there is no instance in which gravity would not hold.
On review, I think I was making a point that was already made.
It does seem vaguely sane to claim that you can’t prove a negative provided there are plenty of caveats attached, but one person I know in particular uses that statement with ridiculous hardheadedness. In such cases, the appropriate response is definitely a demand for proof of their claim.
~ Isaac
Not that you can see, perhaps. But it could be that the Martians are beaming a false image into your head that forces you to not notice the green cat sitting there on your fork. So unless you can prove that there aren’t Martians beaming images into your head, that the cats aren’t too small to see, etc., you can’t prove there are no cats there.
Simply, there are an infinite number of low-probability things which can cause anything to become true. Most of them you can’t disprove, and simply because there are an infinite quantity it is impossible to disprove them all.
It’s still a matter of scope. For example, my former job frequently required me to prove that a parolee did not report to a parole officer on a particular date at a particular place, or did not notify the parole oficer of an event. Parolees frequently claimed that they appeared at the office, but left without signing in or seeing the parole officer, or that they called the parole officer to notify of the event, the parole officer wasn’t available and no message was left. I generally couldn’t prove that the parolee didn’t appear at the office, or didn’t make the phone call (although in some cases, 12 hours of video of the only entrance would prove that he didn’t enter the office) but that wasn’t what I needed to prove. I only needed to prove that he didn’t see or notify the officer, and the officer’s testimony is enough for that .
When the assertion first surfaced about ten years ago, I laughed out loud at its self-contradiction. It impressed me as something that might be said by one of Alice’s characters on the other side of the looking glass:
Hypothesis: I cannot prove a negative.
Proof: I cannot prove my hypothesis.
QED
Well, then you cannot prove that there are any cats anywhere either. Every cat you’ve ever seen have been hallucinations, and everybody else who says they’ve seen a cat is lying. If that’s your definition of “prove”, then you can’t prove a positive either. So what does the negative have to do with it?
Only if you’re a skeptic. There are a number of pretty good replies to the skeptical argument made above. For example, one man’s Modus Ponens is another man’s Modus Tollens.
Unless my basic understanding of the physical world is flawed, isn’t a vacuum a pretty provable negative? Technicality, maybe, but the people spouting this in an effort to sound intelligent never qualify the statement anyway, so let it fall onto them to phrase it better.
When they ask you to prove a negative, ask them to disprove a vacuum. Have fun with them. You may even get to see them bleed from the ears. 
The so-called vacuum is chock full of zero-point energy. You can Google it.
I see your point, which I’d like to discuss. First lets’ get something that I think will be simpler out of the way.
I think your mathematical example doesn’t really address the issue, because esesntially, your negative assertion is merely a contradiction that goes to the very definition of the thing in question.
Same with the triangle, Given our definition of an equilateral triangle, and our commonunderstanding of geometry (in a two dimensional world), you’re merely stating an impossibility.
I know you know all this.
Closer to the point is the Carrier’s idea of a crow in the box. His claim “there are no crows in this box” is a negative and it is easily proven or disproven. That is possible because his claim points to the particular (this box), not to the universal, which is how I was using it. So in that regard you are correct: a negative has been “proven”. But I thiink you would agree that if the claim was universal, it would be much harder to prove-or disprove a claim of “there are no crows in any boxes” or “crows don’t exist in boxes”. But would it be impossible?
Obvioulsy, the less particular the claim is the less likely it is to be able to prove/disprove it. So, as the “particular” (this box) expands to be broader and broader it becomes more and more difficult to be able to prove/disprove. (What RC’s paragraph 2.) If we then move to consider a claim in the universal sense, I think it moves in to the realm of not being able to be proved. Mr. Carrier, or you, might disagree by stipulating that an infinite amount of time with which to search ALL boxes for evidence of crows would eventually reveal an answer, but I’m not sure where this gets us. The question immediately arises: “is an infinite amount of time adequate for one to investigate an infinite number of boxes.” I’ll have to think this over. What do you think?
This brings up the word “prove”. It means different things to the mathematician, logician, and the trial judge. Mr. Carrier points this out in his first paragraph: “This is not “proof” in the same sense as a mathematical proof, which establishes that something is inherent in the meaning of something else (and that therefore the conclusion is necessarily true), but it is proof in the scientific sense and in the sense used in law courts and in everyday life.” I was using it in the universal sense, that which would be used by a logician.
Now, as interesting as might find this (very), I feel compelled to bring up the situation that gave life to this thread. I see you posted a similar post there.
Originally, someone had made a claim that Bush had “legalized and handwaved torture and rape”. I found this to be ridiculous, so I asked him to cite proof that his claim was correct.
Now, whether you agree or disagree with his claim is not the issue. The issue was what should happen next? I asked for a cite, and he just tells me to go look it up, providing some search terms. I tought that this was ridiculous, as well, as he was asking me to read how many articles (?) to finally read the one where he found this information. This is not how debate works. The article link you supplied in the other thread (http://info-pollution.com/ignorance.htm) states what most people accept as normal practice:
It was my opinion that he did NOT have any proof of his claim and that he was “handwaving”, pointing me to Google to find it on my own. How in the hell can any serious person make such a request? He might just as well have said “Believe what I believe because, well, I read some stuff somewhere. here are some search terms.” That’s asinine. As you well know, there are literlally hundreds of hits for just about anything on Google. The responsibility fell to him. I wanted to see the proof and, as is my right as a participant in the debate, to judge both the content and the source. Very basic stuff. He left may to conclude that he didn’t provide a cite because he didn’t have one.
Subsequently, others in the thread did supply some cites, but still, I’m left to wonder if any of those are the cites he hand in mind. Maybe, since he was so sure of himself, he had a better one. All he had to do was act like a sane person and provide the cite. If so, the debate would have stayed more on target than devolving into the nonsense that id did. I take my responsibility for my part in that, but I have a hard time not responding in kind.
I havn’t looked back there for a while, but as far as I know he still hasn’t supplied me with anything but a bunch of links, whcih I assume are similar to many of the links provided by those sharing his position.
I’ve read all of them, as of before hitting the sack last night, and found them helpful in getting a better understanding of where he’s/they’re coming from. I wish he would have steered me to the passage that says to him “Bush legalized torture and rape”. Then the debate could have continued (then again, that’s what he was probably trying to avoid). Insteasd he leaves it to me to divine the link, the article, and the passage. That is just chickenshit, ignorant, lazy, and unfair.
What’s your take on the crows in the box I mentioned above?
The point was that your opinion was worth zilch, as you were totally ignorant and opened your yap without doing a shred of research first. You’re an intellectual whore, remember?
Because they don’t want to cater to a near-troll who can’t be bothered to read a damn thing before he spouts off?
Had you read a damn thing before you spouted off, or read a damn thing after, you’d have known. I even gave you the google search terms. You were, however, a lazy coward who couldn’t be bothered to learn a damn thing before holding forth.
Still haven’t done the research, have you? Coward. The search terms I gave you provided the relevant articles in the first handfull of hits, clearly marked and obvious.
No. As an almost-troll you have no rights. You do not have a right to be an ignorant motherfucker and demand that others cater to your ignorance. If you can’t be bothered to learn a goddamn thing before getting into a debate or after you’re in it, you don’t deserve to participate.
I made my reasons quite clear, and your inability to relate them now is either indicative of you being a liar or a fool. I refused to cater to an ignorant shit stirrer like you. Dig it?
You are a liar. I provided cites as well.
A liar and a coward and a lazy piece of shit.
I provided several, all of which proved my point. You were ignorant of all of them before the debate started, and I believe that since you’re a liar you didn’t even look at them once they were provided.
I do not cater to almost-trolls.
You deserve nothing but contempt. You got it.
Which is it, you liar? Did I provide cites, or not? A “bunch of links” to newspaper articles are, go figure, cites. Lying lazy coward.
Again, were you lying a few sentences up, or are you lying now?
Are you unaware of whether or not I gave you cites, or did you read them?
I’d ask you to quit lying, but I’d wager your already demonstrated massive mouth and zero integrity will take care of that.
You were provided with at least a dozen cites, perhaps more. If you still cannot read English blame your teachers or the fact you’re almost a troll.
Again, liar, I was refusing to cater to a near-troll yapping his ignorant little mouth off. Can you finally understand this?
Again:
Were you lying then, or are you lying now?
Which is it? Did I give you the specific google search terms you’d require to find the articles, or did I ask you to ‘divine’ the links? Did I provide you with cites that you read and evaluated, or did I not?
Can you please keep your story straight and not lie from one sentence to another?
I don’t want to be party to ruining another interesting thread by trying to reason with a foaming-at-the-mouth ass, so Ill keep this short. If you choose to respond to this, I will not. Out of respect for the OP and people who might find this thread intellectually interesting, go foam on the other thread. I’ll go read it. Promise. And we can play your little game there.
But since you’ve put so much effort into sharing your thought here, I’ll take this opportunity to clarify something you seem confused about:
Aside from you confusing what you assume someone has read with what he has actually read,
aside from you confusing what you think an article says with what it actually says,
aside from you confusing looking at words on a page with reading and comprehending them,
aside from you confusing the Mephistophelian George Bush in your mind with the actual George Bush,
aside from you confusing facts with your interpretation of them,
you are very, very confused about one other thing.
You confuse me with someone who gives a shit what you think.
Good, as I’m responding hopefully you’ll shut your ignorant lying mouth finally.
So you were trolling?
Again, this is binary.
Either you knew the facts and you pretended you didn’t in order to stir up shit, or you were ignorant of them and being a loud mouthed ignorant asshole.
Which is it?
You’re the only one who can’t undertand English. Either that or, again, you’re lying. Which is it?
You’re the one who still doesn’t understand what ‘condone’ means.
You’re a fool and a liar. You didn’t do the research before you decided to take a shit in the other thread. Either that or you knew I was right, and decided to troll the thread. Which was it?
I hold no illusions, I know exactly what’s been done, and who’s authorized it. And if you did a simple google search for the terms I gave you, you’d know too.
You’re the one who can’t seem to understand that making things non-illegal and not punishing them is indeed legalizing and condoning them.
Oh, I know, you’re either an idiot or a troll.
But people might be reading along, and I don’t want your lies to stand. How many lies did I catch you in, just in your last post in thist thread? Was it three or only two?
Now be a good waste of space and shut the fuck up, and don’t respond. Bye bye.
My apologies to you Lib, but I did not want the other thread related as if he was acting in good faith and actually deserved to be treated with respect; that’s simply beyond the pale. It was not a question of me getting into a debate with someone and refusing to offer cites, but me refusing to debate with someone who was either flapping his gums from a position of total ignorance while refusing to read a goddamn thing, or a troll. He didn’t deserve a seat at a debate, let alone to be catered to.
His post in this thread was filled with lies, and I do not like being lied about by a halfwit loudmouthed liar without pointing out where he’s lied.
I now return this thread to its previous course.
Uh, looks like you’re getting your ass handed to you here. I’d suggest avoidance of the thread altogether, but I love cheap entertainment. Hell, I watch Jerry Springer every night. This is even more shocking in it’s obvious lunacy beyond that which I’ve ever encountered.
I’ll withhold any references to other threads out of respect to the OP, but I will say this seems mighty deserving of a Pit.
Oh, and Liberal, you know what I meant. [sub]And because it’s the Pit after all[/sub] Fuck off! 
Every negative is a contradiction of its positive; but likewise, every positive is a contradiction of its negative. (A And Not A) is a contradiction. Contradictions are the opposites of tautologies. Contradictions prove everything; and everything proves tautologies. Negation is nothing more than the application of a logical rule to a wiff (well formed formula). You can negate a wiff just as you can modalize it. All these assertions are equally provable (or not):
A — A is true
Not A — A is not true
A — A is necessarily true
So what? Impossibility is merely the negation of modal necessity.
~A — It is not possible that A is true (~ = ~<>)
~A — It is possible that A is not true (~ = <>~)
Nothing can be proved true by empirical observation. Empiricism can only prove things false. That is not a contingency of negation, but of the epistemic nature of empiricism.
No problem. I’ve never subscribed to the theory that every single post in a thread must derive linearly from the OP. Threads evolve and meander. That is as it should be.
I think I first and most came across the “you can’t prove a negative” in skeptical contexts - it being impossible to prove that there is no such thing as esp or psychic powers at all anywhere. No number of tests with negative results will show conclusively that under different circumstances the results might be different.
Huh? That seems equally as silly as the assertion you’re ranting about in the OP. Can you explain in more detail why you feel nothing can be proved true by empirical observation? Especially given your prior conclusion that there’s nothing fundamentally different between logically proving an assertion and the complement of the assertion?
Disregarding the scope argument, there is another class of argument for which no negative can be proven and which I think that the “Can not prove a negative” argument was originally concocted. You can pretty much never prove a negative in matters of faith, definition, (or imagination) because there are no falsifiable assertions. You cannot, for example, prove the negative of the statement, “I have a soul in my pocket.” Because even if I turn out my pocket, the definition of “soul” is untestable – it’s invisible, massless and has no detectable properties. Yet many people will swear to its existence.
How can I prove that a soul does not exist? Any property I assign to it will get defined away. Logic certainly isn’t going to help me here, because logic requires some testable predicates in order to be useful.