On the impossibility of proving a negative

[catsittingstill]

So I was having an argument the other day, and a phrase popped up:

"It is impossible to prove a negative."

At the time I just let it go by.  This phrase pops up a lot in discussions of this type (anything touching on atheism) and it's generally accepted as true and it didn't occur to me to think more deeply about it.  But I was puttering around this morning sweeping the floors and I started thinking about it.

It is impossible to prove a negative.

Let's move it out of knee-jerk territory (at least for many people atheism is knee-jerk territory) and think about some other negatives.

"My plates are not trying to murder me."

"There is not a green unicorn sitting in my lap as I type this."

"The floor will not open up and swallow me when I get up off this chair."

Is it seriously not possible to prove any of these things?  Does the fact that my plates have never tried to murder me before; that I have never heard of plates murdering anyone, that plates have never, in fact, been observed to move of their own accord before as far as I know, much less to move with intent--do those things mean nothing about my plates' current plans with regard to murder?

Well, hmm.  Sometimes something that never happened before happens.  Someone writes a song that never existed before, someone invents something that never existed before...  I guess one can make a case that just because there is no evidence whatsoever that plates have ever murdered anyone or even moved on their own doesn't mean it absolutely can't happen.

So, one could be "aplatistic" on the subject of plates: "I am certain my plates are not trying to murder me."  One could be "platistc" on the subject of plates "I am certain my plates are trying to murder me."  Or one could be "ambiplatistic" on the subject of plates "My plates may be trying to murder me; there is no way for me to be certain."

I suppose one could, technically, make the argument that the ambiplatitisic stance is the only truly correct one.  I mean, if you can't prove that your plates aren't trying to murder you, and you have no evidence that your plates are trying to murder you, then the stance that your plates may be trying to murder you covers both possiblities.

But which one produces more reasonable behavior in real life?  The aplatistic stance would produce the behavior most people (I think) exhibit around plates--we behave as if it never crossed our mind that our plates might try to murder us; we take no precautions whatsoever; we walk through the kitchen without a care, and turn our backs on the plates without a second thought, and handle them with causual, indeed contemptuous, lack of concern.  The platistic stance?  I'm guessing it would involve smashing plates, or possibly banning them from the house.  The ambiplatistic stance--I guess one would tiptoe through the kitchen only when necessary, keeping a wary eye on the plates the whole time.  Or possibly simply ban them from the house, to be on the safe side--though that might be seen as unjust, since there is no evidence that the plates are planning to murder you.

So is it unreasonable to think that a person who smashes her plates to keep them from trying to kill her is...well, psychologically unusual?  Arguably to the point where her ability to live a normal life is compromised?  Is it unreasonable to say that being ambiplatistic--tiptoeing through the kitchen and never turning one's back on one's plates--is silly? 

And if not, does that mean that sometimes it doesn't matter whether or not one can prove a negative?

Comments

[catsittingstill.livejournal.com]

Also, the negative statements you list are not universally recognised as being of the same order as the statement "I sense the existence of an entity I characterise as God,"

Well, yes. I haven't got to it yet, but part of my world view is that the assertion "God exists" gets all kind of special priveledges that other assertions don't get. Part of that priveledge is that "you can't prove a negative" only seems to come up when the negative is "there is no God." It seems to me that if you can prove a negative (not yet demonstrated to my satisfaction), the remaining possibly still true statement is "You can't prove *some* negatives." It would then be necessary to demonstrate that the nonexistence of God is one of those unprovable negatives to use that argument to shut off discussion.

(plates, being man-made things, demonstrably possess no consciousness, perception or volition; the floor around your chair is susceptible to examination for instability; if you had a green unicorn in your lap you would probably not be able to reach the keyboard

1) I certainly believe that plates have no consciousness, but I can't think how to demonstrate that. How would you go about demonstrating it?

2) I certainly believe that floors only "swallow people up" when there is a serious structural instability in them, and that in all other cases they do not--but I don't see how to prove it. Certainly not with the sort of extraordinary proof people demand for the other statement.

3) It could be a small green unicorn. Then I could reach the keyboard. Or it could be invisible and immaterial, then I could see through it and reach through it. These are the kinds of things people postulate about God when other people make what seem to us "commonsense" objections, so why not the green unicorn too? (Though I should note here that the traditional color for the unicorn is pink. I make no explanation of why I have departed from tradition here, and will not contest charges of heresy as regards the unicorn should anyone choose to raise them.)

Clearly, if it makes any sense at all, the statement "it is impossible to prove a negative" cannot apply to this kind of proposition.

So what kind of proposition does it apply to? Universal propositions, perhaps, rather than particular ones, and those whose converse is not excluded from possibility on the ground of absurdity.

Well, that's the rub. I think there isn't common ground on what everybody finds absurd. I find the idea of Satan controlling biologists to believe in evolution absurd, but I know from previous experience that there are people out there who don't find it absurd at all.

I'm also not sure what makes a proposition universal as opposed to specific. I can see that "there isn't a large, heavy, material, green unicorn in *my* lap" is specific, for instance and "there are no real unicorns" is general, but I perceive a gradient between the two, passing through many degrees of specificity along the way. "There isn't a unicorn in my lap." "There isn't a unicorn in anyone's lap." "No one has ever seen a real unicorn." "Real unicorns don't exist." "Real unicorns don't exist and never have existed." I'm unclear on when something becomes so general a negative that it can't be proven anymore.

And to reason from "I do not need to prove that my plates are not trying to kill me" to "I do not need to prove that the sense you have of an entity which you characterise as God is an illusion" is, I think, faulty reasoning based on an incorrect assumption.

I think that to reason from "I do not need to prove that my plates are not trying to kill me" to "I do not need to prove that your plates are not trying to kill you" to "I don't have to prove that you have no right to smash your plates over my head in 'self-defense'," however, is a pretty logical progression. I don't actually mind people who believe they sense God. I mind that subset of believers who are prejudiced against me because I don't believe. I mind that subset of believers who want to enshrine their platist beliefs into laws against making and owning plates (or their religious beliefs into laws against birth control and abortion).

Which is, I think, pretty much what you mind too.

[smallship1.livejournal.com]

I think that to reason from "I do not need to prove that my plates are not trying to kill me" to "I do not need to prove that your plates are not trying to kill you" to "I don't have to prove that you have no right to smash your plates over my head in 'self-defense'," however, is a pretty logical progression.

Of course. But, again, while I am with you as far as that goes, that is not the proposition to which the argument about proving a negative has been applied. If you have no problem with people who simply believe they sense God, but only with people who behave unreasonably in defence of their belief, then the unreasonable behaviour itself is both an easier and a more appropriate target than the belief which is also shared by the innocent.

Conversely, to continue to attempt to discredit that belief (as for instance by trying to establish here that there is no need to disprove it) suggests that your problem, despite what you say, is not exclusively with those who are prejudiced against you, but with all believers whether militant or otherwise. And there we differ.

[catsittingstill.livejournal.com]

Conversely, to continue to attempt to discredit that belief (as for instance by trying to establish here that there is no need to disprove it)

You don't think that the original statement "you can't prove a negative" applied to atheism, is an attempt to discredit *my* belief? Why not?

Or, if it is an attempt to discredit my belief, why is it okay for someone else to do it to me, but not okay for me to do it to someone else?

[smallship1.livejournal.com]

Well, what immediately leaps to mind is that I can't imagine someone coming up to you in the street and saying "you can't prove a negative, you know." It's usually offered, I would say, as a response to an attempt to discredit someone else's belief, in which case one might argue that you started it.

But aside from that, the major point that occurs to me is that, while *I* certainly regard atheism as a belief like other beliefs, and therefore worthy of respect to the same degree to which the atheist respects other beliefs, it has frequently been pointed out to me that I am wrong and that atheism is not a matter of belief but of logic. In which case, we have apples over here and oranges over there, and as far as I know there is no reason not to attempt, by means of logic (however flawed), to test a logical proposition. To get upset over that, as one might get upset at an attack on one's beliefs, is...not logical, Captain. :)

[catsittingstill.livejournal.com]

Well, what immediately leaps to mind is that I can't imagine someone coming up to you in the street and saying "you can't prove a negative, you know." It's usually offered, I would say, as a response to an attempt to discredit someone else's belief, in which case one might argue that you started it.

It is not offered out of the blue, but in response to "There is no God." Which is not an attempt to denigrate a theist's belief any more than "God exists," is an attempt to denigrate an atheist's belief.

Right? Same rules for everybody?

If simply stating something that contradicts someone else's belief is denigration, it's just not possible to have any kind of discussion without denigration. In that case I would like to suggest you either give *both* sides a free pass or make *both* sides shut up. In the latter case, the territory will always belong to whoever speaks first, because no one can contradict the speaker.

So supposing that merely disagreeing with someone is not denigration, no matter whether that person is a theist or not, the response "sometimes it does not matter that you can't prove a negative," ALSO doesn't come out of the blue, and is merely disagreeing with someone, so it shouldn't be denigrating either.

it has frequently been pointed out to me that I am wrong and that atheism is not a matter of belief but of logic. In which case, we have apples over here and oranges over there, and as far as I know there is no reason not to attempt, by means of logic (however flawed), to test a logical proposition.

Okay, the logical proposition has been tested by flawed logic, the flaw has been revealed, and the proposition stands. Presumably you will remember not to use that flawed logic again.

In the meantime, let me put it this way--I would like you to apply the same standards, and the same rules of civility, to both theists and atheists. If "there is no god" is uncivil then "god exists" is equally uncivil. I think that is fair.

[smallship1.livejournal.com]

You do rather seem to be trying to have it both ways here. I will happily apply the same standards and rules of civility to theists and atheists as long as both acknowledge that they are on an equal footing, i.e. people expressing a belief which is not susceptible to proof within the accepted meaning of the word. "There is no God" and "God exists" are in that view equivalent statements, and treating them alike is entirely fair.

If one side or the other allege that their view is privileged in some way, either by the idiocy of biblical literalism or by maintaining that their belief is a proven fact when it is not, then that is a different state of affairs. I expect that from the other side, which is why I am on this side with you. But, as I have said many times now, I expect my side to play by the rules even if the other side does not. If that is unfair, then so be it.

[catsittingstill.livejournal.com]

It seems to me that you are the one trying to have it both ways. Perhaps further explanation of what you consider "denigration" will help. I offered some examples in the previous comment; perhaps addressing them would help.

I expect my side to play by the rules even if the other side does not.

Please establish the rules then.

I keep getting the impression that the other side is allowed to go around saying "God exists" and "It is impossible to prove a negative" as much as they like but you want me to stop saying "God doesn't exist" and "it is possible to prove some negatives; why do you think it is impossible to prove this one?" (if you accept the plate business as proven) or "it sometimes doesn't matter that it is impossible to prove a negative; why does it matter this time?" (if you accept the plate business as impossible to prove.)

Please explain to me what "denigrating" someone else's belief is? Is it disagreeing with that belief? Directly contradicting it? Saying that holding the belief demonstrates the believer is stupid? Or immoral? Is it saying that the belief itself makes otherwise decent people stupid, or immoral? What?

I need to know exactly what it is you want me to stop doing before I can stop doing just that (provided I am even *willing* to stop just that; I make no guarantees until I know what it is). Leaving it vague leaves me feeling that you're pressuring me to stop expressing my views at all. I realize you probably don't mean it that way, so please explain.