You CAN Prove a Negative!

[simplewebportal]

You can't prove a universal negative, that's correct. But you can prove a universal positive: all triangles in the inverse have a sum of the angles equal to 180º. That's because you have the definition of a triangle and you use it as a fact to prove the positive. And it's universal. Thank you.

[velardur]

When you say: there are no quarters in my hand, and then you open your hand,..you havent proven a negative,...

you have proven a positive because you stated that there are no quarters in your hand...

sigh, the humanity,...

it is, in fact, impossible to prove a negative:

for example: it is imposible to prove there are no flying pigs,..because it is impossible to check every pig on the planet earth because one could always use the argument you havent seen all pigs,....

[urpaderpa]

@velardur But pigs cant fly. I dont care about any "You cant prove a negative."

There isn't. It ends there. Pigs dont fly. Maybe they will develop wings and fly in the future, but they cant now.

Thats it, stop fiddling with philosophical quotes, as flying pigs dont exist ATM, I just ignore these super specific quotes. Sure scientifically, with mathematics and stuff, yeah sure cant prove a negative, but save the time, set yourself strong and make the confident statement.

Pigs cant fly.

[sailornaruto39]

you can prove a negative, when the positive exsists.

[13smitbr]

I am an atheist, and I see where this guy is coming from. I respect him for not taking a side and starting a huge troll war in the comment section :)

[stealthgerm]

when you said its impossibe of course .is that a negative as you say? it was said the word is flat explan immposibe

[theUSER101]

I don't think its a negative if you can prove it. I mean you can't prove big foot isn't real. However if you had some kind of technology that can ID every living species on the planet every second of the day. Then you could prove that big foot wasn't real but then it wouldn't be a negative anymore because its something you can prove. If I said I had a U.S. Quarter on or in my tail. Well... I don't have a tail...so thats a negative.

[KarinMikazuki]

No you still can't prove a negative hun

[drrobertoboogie97]

@KarinMikazuki You're saying that you can't prove 2+2 isn't 3.

[KarinMikazuki]

@drrobertoboogie97

I can prove that 2+2 is infact 4

[Enigma542]

Sounds like a fallacy, but I'm not entirely sure.

[Entertainmentwf]

I'm glad someone made a video to acknowledge that you can actually prove a negative. I think maybe the deliver is not the best since proof is a mathematical/formal term not an empirical term which I think you are trying to do. Demonstration is not the same as a proof.

An example of a proof of a negative is that there does not exist a universal Turing machine that can halt on the decision problem.Formal scientists prove negatives a lot likewise universals a lot especially in theoretical fields.

[ourhandsaretied]

For starters we do know that gravity is different in different parts of the universe (for instance it is much weaker on our moon), but i get your point.

I think you're arguing on a technicality here though: the important 'you cant prove a negative' debate is about disproving God, which, obviously, is impossible because it is what you describe as a 'universal negative. So the point you are trying to refute still stands.

[HavocGunStar]

@ourhandsaretied Whut. Gravity works the same on the Moon as it does on Earth. It is a function of the mass of a spatial object. The moon has less mass, therefore it has proportionally less gravity. Different by an amount that can be predicted precisely based on the moon's mass.

[ourhandsaretied]

@HavocGunStar

Exactly; 

[HavocGunStar]

@ourhandsaretied No, not 'exactly', the nature of gravity is the same on the Earth as it is on the Moon. It is not 'different' on the Moon. Not within the connotation the author of this video was suggesting, such as gravity repelling instead of attracting, or being a function of velocity instead of mass, etc.

[synchronium24]

Also, some people think this is just a linguistic trick, but my favorite way to prove you can prove a negative is a double negative: "poptarts do not NOT exist"

i.e. poptarts do exist. and i CAN prove this claim.

I'm confused about your gravity example, though. Traveling everywhere in the universe is impossible from a practical standpoint, but doesn't the statement only have to provable in principle?

[CamronJLB]

your definition of proof : a demonstration that will convince someone else to accept a claim to be true.

That isn't proof. Proof is evidence that something is factual.

The difference?

Your definition means that when Criss Angel made it seem as if he went through a wood chipper and reincarnated himself, and convinced a crowd of hundreds, as well as many more viewers in tv land... he has proven that he has done so.

Mine means that if I tell you that I have an apple, and then hand it to you

[CamronJLB]

I have proven that I have an apple.

[logician360]

To the extent that you can prove anything, you can prove a negative.

[synchronium24]

@logician360 Exactly! We're not talking cartesian doubt This applies in the same way as the whole agnostic/gnostic distinction. As far as the validity (methodological soundness and degree of certainty) of a scientific theory goes, you CAN prove God doesn't exist. And if a Deist god exists, it's irrelavent to science anyway.

Crake's argument below demonstrates why we can't Know (capital K) that the coins aren't in his hands. But we do know US quarters aren't invisible in all tested situations.

[Crake777]

The coins in your hands are invisible and thus do exist. We just can't see them.

[fatfist]

Positive universal statements can be proven.

"All human beings have lungs".

Universal negative statements can also be proven.

"No human being is a single-cell creature".

[spaceshipable]

not all humans have lungs, i cut someones out

[fatfist]

Ahhhhh, but they did have lungs. So they were human when they had lungs! By cutting out their lungs, you have proved that this human had lungs.

Any body modifications do not falsify my statement.

[Pdrum2]

every negative affirms a positive, if you proof that God does not exist then you have to affirm his existence to know that he doesn't exist, which means you either know or you don't. In order to say this is negative you must affirm what is, you can't say "you can't prove a negative" meaningfully.

[tillnow67]

There are no square circles. Negative universal statement. All that is needed to prove it is a basic understanding of what defines squares and circles. Prove that they are by definition contradictory and cannot exist in the same entity and you have proven that they don't exist.

[CousinoMacul]

I thought I mentioned tautologies in the video.

[velardur]

@tillnow67 sorry,..but that isnt prove of a negative because there are no square circles simply because they apply to theoretical, man-made, non-existing objects in itself,....i know this sounds strange,..but if you dont understand this, you dont understand the meaning of a "negative"...

like you say it, it is easy to prove God doesnt exist, because all-powerfull beings cannot exist, for it is impossible do do the things you cannot do,but all powerful beings must be able to do so: contradiction

[BeHereNow21]

You forgot to mention statistics. It´s so highy improbable that gravity would be different on that other moon - that you might as well say it´s impossible.

[frazzzer8888]

Pure semantics.

To use the unicorns example, an idiot may claim "Unicorns Exist". A rational person would refute it. The idiot would then say "You have to PROVE they DON'T exist,otherwise it means they DO exist."

NO. The BURDEN of proof is not on the person to prove unicorns DO NOT exist.

It's 100% on the person who makes the claim that unicorns DO exist. If they can prove it, all the power to them.

[CousinoMacul]

Semantics are important because they are the instrument of all debate.

I understand burden of proof and I agree with you. My qualm is with the claim "you can't prove a negative" which while I understand what is usually meant by that and I realize that it's usually brandied out as a response to an ineptitude like "you can't prove god doesn't exist', doesn't change the fact that the claim is just wrong.

If one is going to refute bad arguments, one should do it correctly (imo).

[flight1100]

@CousinoMacul No No No. The fact that I can not prove a positive with out the information needed to do so does not equal proving a negative.

[cjunk351]

no no no. can't PROVE a negative means that if something does not exist, it can never be PROVEN to exit. that doesn't mean you cannot convince someone it exist.

People often confuse Difficult to prove with Impossible to prove.

thats why we 'prove negatives' all the time, people are getting confused with the conecpt.

cant prove a negative still stands.

[CousinoMacul]

If you want to say that something nonexistent can't be proven to be nonexistent, then just say that. But as long as you keep saying "you can't prove a negative", then you're making a demonstrably false claim.

[cjunk351]

Actually, If a claim is untrue in reality then that is the positive. Its just often times very difficult to prove,not always impossible. eg, its possible to prove there is no Elephant in my kitchen. It just has to be done indirectly.

If something is not actually true, it can never be proven to be true, that is "you can't prove a negative".

[CousinoMacul]

"Actually, If a claim is untrue in reality then that is the positive."

wtf? No! That's not what is meant by a negative claim.

[cjunk351]

Actually "cant prove a negative" is a philosophical' notion. Meaning that something which is untrue in reality can never be proven to be true. meaning that one cannot prove a negative. the statements "prove I do NOT have a vagina" does not fall under this category directly. A response such as "I cant prove you do NOT have a vagina because one cannot prove a negative" is a misuse of the notion. for it is stating that the positive is i do have one, and thats why you cannot prove that i dont.

[KoDT69]

No, actually you can't prove a negative. If it does not exist, there is nothing to test. There is no way to observe all of existence simultaneously. Proving a negative to one person and their opinion proves nothing.

[CousinoMacul]

"There is no way to observe all of existence simultaneously."

It appears that you've missed the entire point of my video. Not all negatives are universal! For example, the statement "There have been no female presidents of the United States" is a negative. It is also trivially easy to prove (just list the 44 MEN who have held the post).

[raoskaos]

Maybe somewhere in the universe gravity doesn't exist?!?!?!

hmmm......wise words you speak.

Keep on thinking, ot just try.

[randallsnowb]

hey cousinomacul, i agree with your video about how negatives can be proven, but I have a quick question about where you said that a universal cannot be proven. what about mathematics? like 1+1=2? isn't that a universal that can be proven?

[CousinoMacul]

I oversimplified in my video (to keep it short); what I should have said was that all non-tautalogical universals are unprovable.

So a universal statement such as "All green sheets are green" is provable because the claim follows directly from the definition of "green sheet", and hence is a tautalogy. It does not require testing every element to prove it.

All true logical and mathematical statements can be expressed as tautalogies.

[bobcarp23]

Prove you've NEVER killed someone.

[CousinoMacul]

Did you even watch my video?

[bobcarp23]

Yes I did watch it. Now prove you've NEVER killed someone.

[CousinoMacul]

Then perhaps you had the volume off because you completely missed the point of my video. I wasn't making a universal claim (I wasn't saying "You can ALWAYS prove a negative."). My claim was to refute the ridiculously wrong universal claim that "You can't prove a negative." I don't need to prove your negative to make my point. I just need to find one counterexample (a provable negative). I did that when I proved that there was no coin in my hand.

[bobcarp23]

But a believer would say, You do have quarters in your hand, theyre just invisible quarters.

Im sure you are familiar with Carl Sagans essay Theres a Dragon in my Garage. Someone who wants to believe that there is a god, or a dragon in Dr. Sagans garage, or U.S. quarters in your hand, would not be satisfied with not seeing the quarters.

I'm not criticizing your argument, I just enjoy discussing logic and most people I know do give a crap about it.

[bobcarp23]

One could even claim that you are not proving that there are NOT (negative) quarters in your hand, but you are proving that your hand IS (positive) empty.

[albertfishsticks]

I'm going to have to watch that a second time, not from lack of understanding but I missed some of what you said because I was too busy drooling over your sexy stubble :)

[CousinoMacul]

:-)

[dakshinamurti]

loved it hehehe

[mtanti87]

makes perfect sense...

[WyteBudz]

I wanna take sum psycodelics wit you... probly be pretty deep.

[RyuuKyuzo]

whoah...... I need to re-watch this a few times o.O

[Litkisla]

whats sthat really high pitched noise in the backround

[CousinoMacul]

It's an artifact of my recording device. I've corrected it in my latest video (and will do so in subsequent videos), and perhaps will re-upload this and other past videos in "de-noised" form. But until then, sorry!

[Pennys1]

Man, you'll make a good philosophy teacher.

[booeing2007]

Taking this a step further. I tell a dog the derivative of ln(x)=1/x (and it does). My dog and the thousands of dog I've met haven't have no way of falsifying this because it's way outside their real of understanding. What if humans are the dog and some supernatural phenomena are our ln(x)?

[CousinoMacul]

Aha, now we're moving into the realm of what constitutes a proof (or a falsifiable claim, etc.). This is all interesting territory to explore and possibly the subject of many future videos.

[frankjohnson123]

I found a problem with your theory that for every positive there is a negative. Although not really relevant, here it goes. Positive: i have five fingers on my left hand. Negative: I don't have six fingers, I don't have seven fingers... So you can see there are infinitely more negatives than positive.

[CousinoMacul]

I don't have either less than nor more than five fingers on my left hand.

[frankjohnson123]

Ah, good point. Thank you.

[booeing2007]

Food for thought:

How much do we trust our eyes?

What if I limit my domain to, say my room, and I claim there is a ghost in my room but currently (given our observation methods/technology) there is no way to test for it (analogy similar to Rusell's teapot). Falsifiability would say I'm BSing. Ok....But, what about humans 2000 years ago who had no way of testing the Earth was round and not flat?

[booeing2007]

Milky Way is not universal, and yet we can't prove either statement. But not because the statement is negative or positive, but because the domain is outside our current limits. Once we develop a super-powerful, intergalactic, no-error, green-swan scanner, we can scan the Milky Way and confirm the statements. (Assumptions: We trust the scanner to tell us the presence of green swans at least as much as we trust our eyes to tells us the presence of quarters in Javier's hand.)

[booeing2007]

The issue of positive or negative statement is a distraction. The central issue in the debate is DOMAIN - time, physical space, or something else - which, in Javier's example, is the physical space bordered by his hand. But, it is NOT necessary for a statement to be a universal for it provable or unprovable. The statement simply has to encompass a domain larger than is possibly falsifiable.

Ie. "There are no green swans in the Milky Way" = "All Swans in the Milky Way are non-green."

[CousinoMacul]

I was considering bringing up the point that every negative statement can be reformulated as a positive statement and vice versa (as in your "Milky Way swan" example), but I wanted to keep my video short, so I scrapped that part.

Thanks for the insightful comment. (You're right of course: a claim need not be universal to be unprovable, and a universal claim can be provable if it's tautological--"All green swans are green.")

[btsumm]

Thanks for the insight bro.

Peace,

B

[0rcryst]

Oh Em Gee! It's Joe Satriani!

[CousinoMacul]

Except that I can't play the guitar. :-(

[baconeater]

Sorry dude, but I'm pretty sure I saw an American quarter in your palm. I was hammered at the time, but I know what I saw.

[CousinoMacul]

You must've been hammered! That was obviously a Canadian quarter. ;-)

[rozeboosje]

You've just proven yourself absolutely correct. Now what!?

[KYASHAAAN]

You did not prove that you had no US currency in your hand. You may have used some sort of teleportation device to remove it from your hand the second you opened it. Reasonable doubt, lol.

[CousinoMacul]

You caught me!  :-)

[VoicesintheHead]

You're on a roll today! This is a very interesting video, and i remember reading a paradox about this. It was about easter bunnies not being found. Can't remember though. Do you remember?

[CousinoMacul]

No, but it sounds interesting.

[TruthSurge]

No, you didn't prove the negative. I'm not convinced you didn't do it with after effects trickery!!!! :)

[TruthSurge]

hahahah Gravity has been proven to work differently. Remember that trip we made to the moon? The gravity there was about 1/6 of Earth's. Besides, using your OWN DEFINITION, your argument on gravity fails. Scientists DO know it exists and that it works differently on different planets and so the proof is good enough to "convince someone else to accept as true the claim you are making". Who on this planet disagrees with the theory of gravity?

[CousinoMacul]

But we expect the force of gravity on the surface of the moon to be 1/6 of that on the surface of the earth because of Newton and Einstein --- F=Gm1m2/d^2  ;-)

[TruthSurge]

I suppose my point was that although no one can know via experience that gravity is the same on all planets or places, we can feel sure enough through a) the two bodies we HAVE walked on and b) scientific formulas that have proven true on THOSE two bodies as well as all other evidence that points to it being true

So, that was my point. Althought in theory we cannot prove gravity works the same way everywhere, in practice (pragmatically), no one is saying otherwise. ? I think that's me pt.:)

[lulhoofd1]

The Flat Earth Society would disagree with you. If the earth is flat, and we would still be pulled to the centre of it, we would be sliding along the ground.

[DieselBodine]

Good point, Mr. Javier.

[CousinoMacul]

Thank you, Mr. Scott!

[HaleyMary]

But, if most negatives are universal, and you can't prove a universal, wouldn't it still be impossible to prove s negative? Just stating my opinion.

[HaleyMary]

I meant a negative. Typo. :P

[CousinoMacul]

In one word, no. Every negative statement can be rephrased as an equivalent positive statement, and vice versa. For example: "you can't prove a negative"="you can only prove a positive" and "the supernatural isn't real"="only the natural is real" etc.

The negativity has NOTHING to do with a statement's provability.

[chris123abc]

Say what you wanna say, I still think you can't prove a negative. That's my opinion though lol.

[CousinoMacul]

That's OK, I'm used to it. On one of my other videos, I get comments to the effect of "Mathematical Proof-Schathematical Proof: I still don't believe that 0.999...=1" so I completely understand if you want to deny what is logically apparent. ;-P

[ChaosAngel667]

I can prove there are not prime even number bigger than 3.

I can prove there are not rectangles with diagonals smallers than their sides, I can probe there is not way to get 5 queens on poker.

[CousinoMacul]

Indeed you can. But all those proofs are within well-defined closed systems (numerics, euclidean geometry, 52 card standard deck) and so are NOT universals--I needed to keep my video short, so I didn't get into what a proof was or what a universal was.

Within a closed well-defined system, you can prove "absolute" statements using rigorous logical rules. But for common rhetoric, the standard is (and must be) different

[micp4130]

well, i presume you're referring to the religious debates on youtube... but we still have the same problem since god could be anywhere in the universe... so the video's not really helping, it's just correcting our manners of speech... it is an interesting point though... just not that helpful...

[CousinoMacul]

Well, virtually all human communication is through speech, so I think making sure that you get it right is in fact important and also quite helpful for advancing the conversation.

[premed2]

A very entertaining and well explained vid, but I was distracted by the cruelty of keeping monkeys in barrels and found it necessary to rewind the vid on several occasions.

[CousinoMacul]

Well, at least the monkeys are having a lot more fun than those fish over in the other barrel that are just waiting around to get shot.

[premed2]

LOL!

[trick0171]

The scientific method proves negatives all of the time. I hate when people use the "you cannot prove a negative" fallacy. What they really MEAN to say is, the burden of proof is on the person claiming a negative.

[trick0171]

Another way to put it is: in order for a statement to be logical, it must be falsifiable, which means that it has to be presented in such a way that it could be proven incorrect. A statement is not logical if it cannot be tested to make sure it is true. The non-existence of certain mystical beings usually fall into this category.

[Darwinsgift]

Interesting! This must a US saying though! It is not a familiar phrase to me!

[CousinoMacul]

You hear it on YouTube all the time.

[Loreleila]

You seem to be assuming that a fact is a positive. Surely it's just an 'is', at least in the corner of the universe in which we reside. How does that make it positive, or negative? Is the statement: 'I just murdered so and so' positive if it's true and negative if it isn't? Surely positive and negative are only truly definable as attraction and repulsion as in magnetism, or a spectrum of pleasure/pain which is subjective.

[CousinoMacul]

The other point that I didn't bring up is that every negative statement can be rephrased as an equivalent positive statement and vice versa. That also refutes "you can't prove a negative" (or "you can only prove a positive" if you prefer.) ;-)

[nicanicabad]

ver cool!

[dsi3]

Well actually you cant, because its negative and its socially unacceptable, or at least you have to make it a joke. We don't want any negative things.

[CousinoMacul]

"We don't want any negative things."

Couldn't you find a positive way to phrase that?

;-P

[codrutza01]

The is NO way you can prove a negative. Wat you did there was not a negative. If you say "There is noting in my hand" that is NOT a negative. A negative would be you saying "There is no evidence there is something in my hand, therefor there must be nothing in my hand". And you will say that without ever opening your fist. That is a negative ... not what you did.

Also your definition of "proof" is very ... hm ...silly, to say the least.

[CousinoMacul]

No, you've just redefined "negative" in terms of a universal. Why don't you try to prove a positive universal such as the gravity example?

[codrutza01]

But I don't NEED to prove/disprove a positive. In fact, the only negative that I hear at least 5 times a month is "there is no proof *insert phantasmagoric crap here* is not real, so that means it is real

You really give fuel for the retards with this. Because they are either not capable of understanding what you try to say in regard to the universals, or simply in that "lalallala - I hear want to hear - lalalalala" mode, and your use your statement to further convince themselves and others.

[CousinoMacul]

Whether you think that you need to prove anything or whether idiots do or don't understand my point doesn't change the fact that I'm right.

[codrutza01]

You can basically distort ANY concept and be right about it. It is also an interesting thing to do, I don't deny that. But you may want to consider the fact that you have a very convincing way of presenting things, and that in some cases your persuasion can be in fact DANGEROUS. I don't know if you care about that ... but I suspect in the near future I will hear this argument used in the "wrong" way by "wrong" people, probably with good results.

[GnosticAtheist]

I an just jumping in here for good measure.

(Pardon my English skill if you see any errors, I am not English)

Empirical evidence in this context is demanded to hold different standards to be accepted as proof based on wheter the claim was closed or open. I suspect the usage of the term universal stems from this.

Claims, negative or positive, in an open systems cannot be falsified. Claims, negative or positive, in a closed system can be falsified as long as he closed system is within reach

[GnosticAtheist]

Here, the problem is that many will say that all systems except the universe as a whole is open systems rendering the entire definition closed system useless, except when talking about energy. As such, I would agree with the video host that negatives, when not universal, can be verified when a process of falsification is within physical reach.

[azrienoch]

Funny, what you do in showing that you can prove a negative when someone says otherwise, is disproving a universal. Or if the two claims were reworded to "Only positive statements can be proven," and "That's not true," you not only disprove a universal, but you prove a negative.

(Incoming pm on a a related topic.)

[CousinoMacul]

I had to read that three times, but right on!

[sadius24]

also your definition of 'proof' is terrible, by that definition one could prove almost anything just by finding someone gullible enough :P

[CousinoMacul]

As I said, I'm working on a video "What is a proof?" (perhaps I should have done that one first)

The thing is, a proof essentially comes down to convincing others. Certainly formal deductive (logical or mathematical) proofs have more stringent guidelines, but those wouldn't apply to most claims, or else nothing outside of formal systems would be provable. Also, a formal proof is no guarantee that people will be convinced (check out the comments on my "0.999...=1" video) ;-P

[2bsirius]

You're right! Among professional logicians, guess how many think that you cant prove a negative? Thats right: zero. Yes, you can prove a negative, and its easy, too. For one thing, a real, actual law of logic is a negative, namely the law of non-contradiction. This law states that that a proposition cannot be both true

and not true. Nothing is both true and false. Furthermore, you can prove this law.

negative. So weve proven yet another negative!

[CousinoMacul]

Yes, I love how the law of non-contradiction is both true and false.

[sadius24]

You're absolutely right, I get so sick of otherwise intelligent people repeating this "can't prove a negative" mantra. But you can also prove a universal statement by reductio. Perhaps it would be more accurate to say that you can't prove an informative (i.e. non-tautological) universal?

[CousinoMacul]

Yes, of course tautological universals are provable--positive or negative: "No atheist believes in a god."  And naturally, any statement that can be reduced to a restating of the definition of a term used in the claim can also be proven. :-)

[ZOMGitsCriss]

Yes, good point. But you demonstrated here that you can prove a negative if YOU are the one making that negative. You should extend that a little

[DamNationDiplomat]

I've often said "'Always' and 'never' are the two most dangerous words," but I think 'you cannot prove a universal' is a much more accurate, much more developed, and a much more intellectual view of that sentiment. Well done.