logic 101 proving negatives

Ry
Posts: 36
Joined: 2006-03-10
User is offlineOffline
logic 101 proving negatives

someone actually asked me

Well "can you prove or disprove aliens exist?"

So here is my reply and this goes for gods demons agnles eleves and everything else with no empirical evidence.

can you prove or disprove unicorns exist? You can not prove that unicorns do not exist.

It stands that aleins do not exist (especially in humanoid forms on earth) until there is proof that they do exist. You don't prove negatives otherwise you have to believe in any and everything I can invent until it is disproven which it can't be because its a negative.

You can't prove innywots don't exist. The burden of proof is on the asserter. They have to prove it does exist. (not it is just possible for them to exist, but that they do exist.)

If I say godzilla likes peanut butter, you can not prove that he doesn't because there is no godzilla. I however can not prove that he does for the same reason. But you don't just assume he likes peanut butter, you assume that he doesn't like or dislike peanut butter because he is not real.

Can we prove godzilla is not real? No, because it is already proven by that fact there there is no reason to believe he is real not a shread of evidence. If you just want to decide to believe in things without evidence, or worse yet contrary to evidence then that is illogical. And if you scoff at logic then how can you read this? Without logic there is no principle of uniformity. You know what we call those who just pick and choose to follow logic or ignore it based on their needs? Fools and or the insane.

That's logic 101.

Warning, religiousity increases the risk of religious terrorism.

www.anti-neocons.com or www.Rys2sense.com


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
Re: logic 101 proving negatives

Ry wrote:
It stands that aleins do not exist (especially in humanoid forms on earth) until there is proof that they do exist.

So an aliens ontology is contingent upon our proving it? What kind of retarded metaphysics is this?

Perhaps what you mean, is that until there is good evidence for aliens existing on Earth, humans are unjustified in believing in them. I would agree with you on this latter statement.

However, aliens could exist on Earth, but just in disquise. is this probable? No. However, its possible.

Ry wrote:
You don't prove negatives otherwise you have to believe in any and everything I can invent until it is disproven which it can't be because its a negative.

this makes no sense. Science proves negatives all the time. This doesn't mean they believe everything.

Here is logic 101 for yeah -

P --> Q
~Q
-----
~P

This is called Modus Tollens. If the argument is sound, this is proving a negative.

Ry wrote:
You can't prove innywots don't exist. The burden of proof is on the asserter. They have to prove it does exist. (not it is just possible for them to exist, but that they do exist.)

obviously. Care to tell us something we don't already know?

Ry wrote:
If I say godzilla likes peanut butter, you can not prove that he doesn't because there is no godzilla. I however can not prove that he does for the same reason. But you don't just assume he likes peanut butter, you assume that he doesn't like or dislike peanut butter because he is not real.

It cannot be proven or disproven because there is nothing within the concept of Godzilla that would determine the truth of the proposition "Godzilla likes peanut butter". Furthermore, since such a creature does not exist, there is no way for me to empirically verify such a proposition.

Just because Godzilla does not exist, doesn't mean I can claim things about him. I do not know of the creature "Godzilla" very well. However, I do know things about "Unicorns", so i will be using them for my example:

If i say "Unicorns have only 1 horn" this is a true proposition, even though unicorns do not exist. Why? Because "...having only one horn" is built into the very concept of a unicorn. Whereas "has exactly 3 million hairs" is not.

See the difference?

Ry wrote:
Can we prove godzilla is not real? No

Incorrect. We can prove that based on what we know about biology, it is inductivly improbable.

Ry wrote:
because it is already proven by that fact there there is no reason to believe he is real not a shread of evidence. If you just want to decide to believe in things without evidence, or worse yet contrary to evidence then that is illogical.

No, this would be bad epistemology, it has nothing to do with logic. Logic deals with validity. not whether someone is justified in believing something or not.

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Sapient
High Level DonorRRS CO-FOUNDERRRS Core MemberWebsite Admin
Sapient's picture
Posts: 7530
Joined: 2006-04-18
User is offlineOffline
logic 101 proving negatives

Chaos... do you consider saying "no square circles exist" or "no married bachelors exist" is proof that you can prove a negative?

- Brian Sapient


Buy popular atheist books and support the Rational Response Squad at the same time on Amazon.


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
logic 101 proving negatives

Sapient wrote:
Chaos... do you consider saying "no square circles exist" or "no married bachelors exist" is proof that you can prove a negative?

of course.

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Sapient
High Level DonorRRS CO-FOUNDERRRS Core MemberWebsite Admin
Sapient's picture
Posts: 7530
Joined: 2006-04-18
User is offlineOffline
Re: logic 101 proving negatives

Chaoslord2004 wrote:

Ry wrote:
You can't prove innywots don't exist. The burden of proof is on the asserter. They have to prove it does exist. (not it is just possible for them to exist, but that they do exist.)

obviously. Care to tell us something we don't already know?

Yeah, we know, but some Christians (plenty reading these forums) don't know.

- Brian Sapient


Buy popular atheist books and support the Rational Response Squad at the same time on Amazon.


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
Re: logic 101 proving negatives

Sapient wrote:
Chaoslord2004 wrote:

Ry wrote:
You can't prove innywots don't exist. The burden of proof is on the asserter. They have to prove it does exist. (not it is just possible for them to exist, but that they do exist.)

obviously. Care to tell us something we don't already know?

Yeah, we know, but some Christians (plenty reading these forums) don't know.

Or, they know but they just don't care. Whats more probable, that the theist is intellectually dishonest or that he is ignorant on the burdon of proof? I think the former is...but that is just my cynical opinion

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Obscure
Posts: 8
Joined: 2006-04-13
User is offlineOffline
logic 101 proving negatives

Proving a god doesn't exist, or that theism is false, is quite possible. Arguing from non-cognitivism (meaninglessness of the existents claimed by theists), ontological arguments, and the materialist argument will get the job done. Saying you can't prove a negative is another close minded theistic tactic to disarm the majority of atheists who don't possess the intellect to deal with that little phrase.

I could always be smarmy and say that Danny DeVito is not taller than Shaq. Technically, i've just proved a negative, however, I realize that is not what you meant.


Ry
Posts: 36
Joined: 2006-03-10
User is offlineOffline
logic 101 proving negatives

Quote:
It cannot be proven or disproven because there is nothing within the concept of Godzilla that would determine the truth of the proposition "Godzilla likes peanut butter". Furthermore, since such a creature does not exist, there is no way for me to empirically verify such a proposition.

Just because Godzilla does not exist, doesn't mean I can claim things about him. I do not know of the creature "Godzilla" very well. However, I do know things about "Unicorns", so i will be using them for my example:

If i say "Unicorns have only 1 horn" this is a true proposition, even though unicorns do not exist. Why? Because "...having only one horn" is built into the very concept of a unicorn. Whereas "has exactly 3 million hairs" is not.

You are not talking about unicorns you are talking about the unicorns story. It is like saying well Vampires like blood. (or Santa has a beard) That is true is the sense that according to the compiled stories about vampires they like blood. However vampires are not real so they don't like (or dislike) anything. In the philosophy of language you have to determine what a name/title picks out. And is it from the actual world or just a discription or fiction about it? And if you are talking about existence then you are not talking about stories but real objects. If we talk about a historical person, (an object) they do not exist, that is they currently are not real (not here). However they used to exist. Their story is all that is actually left. BUT as real existing things (objects) their stories must obey the said unchaninging laws of Physics. Was Geroge Washinton an American General, yes. Did he throw a silver dollar acorss the Patomic river. Probably not unless the river was much smaller back then. Was Buddha real yes, did he sleep under tree for 29 days or have a giant cobra sheild him from rain? No.

Quote:
So an aliens ontology is contingent upon our proving it? What kind of retarded metaphysics is this?

Perhaps what you mean, is that until there is good evidence for aliens existing on Earth, humans are unjustified in believing in them. I would agree with you on this latter statement.

However, aliens could exist on Earth, but just in disquise. is this probable? No. However, its possible.

it's not metephysics. It is not contengent on our proving it. It is saying what is rational to believe. someone else wrote to me

Quote:
Just because I cannot directly percieve or logically infer something does not grant me license to write it off as unreal. It exists as a possibility and I must give it credit for that, even if it is highly improbable.

Nobody believed in the Kangaroo for years, but it exists.

It seems to me that cutting out and discounting what you don't believe in is dangerous. Empiricisim leads to Empire.

so I siad

kagaroos are precievable and people in Australia were seeing them that is why they talked about them. NO one in Europe just invented it and then oh wow they just happened to discover something just like they imagined.

The chances of just inventing a creature and then it being real just because you imagined it (wwith no deductive science) are nearly immpossible. (no historical argument for it)

Kagaroos are also empirical. Math is not. And Aliens would be but since NO ONE can offer any evidence nor a place to see them, they are more likely than not bullshit.

I saw a new raccoon here in Japan it doesn't exist anywhere else. I didn't disbeleive it though before i saw it, because Japanese people has seen it.

That's far far different than just making a creature up out of thin air and then discovering it in Japan. You get it?

big difference between what possible and what is actual. There is no reason to accept something as real just because there is a .000000000000000000000000000000000000000000000000000000000000000000001% it could be.

Let me put this into context for you. What started this was a guy who think that Queen Elizabeth is a space alein in that can change its form for a fish like thing into a human. Now is that possible? Technically it is since we don't know about all the being is the universe. But is it rational to believe in just anything just because it is possible? No. If there is no evidence for something and I mean zero, then there is no reason to jump to conclusions.

Warning, religiousity increases the risk of religious terrorism.

www.anti-neocons.com or www.Rys2sense.com


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
logic 101 proving negatives

Ry wrote:
You are not talking about unicorns you are talking about the unicorns story. It is like saying well Vampires like blood. (or Santa has a beard) That is true is the sense that according to the compiled stories about vampires they like blood. However vampires are not real so they don't like (or dislike) anything.

Do you actually have anything intellegent to say, or are you content with pointing out the obvious?

Vampires don't REALLY like or dislike anything? No fucking shit.

The concept of a vampire (for instance) has built into it the very notion that they like to drink blood. Do they REALLY like to drink blood? No, but this was never at issue here.

Please, if you have nothing better to do then play petty semantical games, go waste someone elses time.

Ry wrote:
In the philosophy of language you have to determine what a name/title picks out. And is it from the actual world or just a discription or fiction about it? And if you are talking about existence then you are not talking about stories but real objects. If we talk about a historical person, (an object) they do not exist, that is they currently are not real (not here). However they used to exist. Their story is all that is actually left. BUT as real existing things (objects) their stories must obey the said unchaninging laws of Physics. Was Geroge Washinton an American General, yes. Did he throw a silver dollar acorss the Patomic river. Probably not unless the river was much smaller back then. Was Buddha real yes, did he sleep under tree for 29 days or have a giant cobra sheild him from rain? No.

thanks for pointing out the obvious.

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Klarky
Klarky's picture
Posts: 70
Joined: 2006-04-10
User is offlineOffline
logic 101 proving negatives

Here's a piece from Franc Tremblays "Handbook of Atheist Apologetics" which he sent me a few years back. It sums up the ability to prove certain universal negatives, pretty much inline with chaoslords example regarding non-contradictions.

Quote:
The possibility of universal negatives

It is generally accepted that universal negatives, claims that something does not exist, cannot be proven without a wide breadth of knowledge. An example of this would be :
P1 : There are no unicorns.
While generally speaking P1 is true because there is no known unicorn species, the possibility that a unicorn exists somewhere is, we presume, non-zero (trivial, yes, but non-zero). So most universal negatives of this type are impossible to prove.
But some other universal negatives are trivially easy to prove. Take the following proposition :
P2 : There are no invisible pink unicorns.
P2 seems to be of the same form as P1. However, the attributes invisible and pink, applied in the same respect here, are contradictory. A unicorn can either be invisible or pink, but not both. Something pink can be
made invisible, but in that case "invisible" and "pink" do not apply in the same respect as they do here.
It is a basic law of logic that contradictions cannot exist, regardless of the context. No opposites can coexist in the same respect. This applies to internal contradictions as well as external contradictions, as we can
see with P3 :
P3 : There is no entity X such that if X exists, this sentence does not exist.
P3 is necessarily true since the sentence (P3 itself) exists ! One can attempt to contrive all sorts of rationalizations, but the basic fact of the matter is that contradictions cannot exist. To refuse to acknowledge
this is to put oneself outside of all discourse (let alone rational discourse), since the meaning of discourse is based on logic. To the illogical, no response is possible - it is misunderstanding at best, insanity at worst.


todangst
atheistRational VIP!
todangst's picture
Posts: 2811
Joined: 2006-03-10
User is offlineOffline
logic 101 proving negatives

We make universal negative statements all the time and the dictum "you can't prove a negative" is itself a universal negative statement, isn't it?

Basically, unless you hold to some form of dialetheism (a system of logic that allows for true contraditions), contradictions are always false. So we can "prove a negative" by showing that a claim is internally inconsistent. This is what Franc demonstrates in the quote section in the last post.

As for incoherent declarations (non cognitivism) I do not feel that an incoherent claim is 'false' - an incoherent statement is simpy incoherent, and no truth or falsity can be applied to it in the first place.

Those who know the good, do the good. - Socrates

Books on atheism.


Klarky
Klarky's picture
Posts: 70
Joined: 2006-04-10
User is offlineOffline
logic 101 proving negatives

todangst wrote:
As for incoherent declarations (non cognitivism) I do not feel that an incoherent claim is 'false' - an incoherent statement is simpy incoherent, and no truth or falsity can be applied to it in the first place.

Yes that?s a good point, in the example I gave the statement fails due to its incoherency; it being illogical, it doesn't get to the point of qualifying as a universally negative statement. Point taken.


todangst
atheistRational VIP!
todangst's picture
Posts: 2811
Joined: 2006-03-10
User is offlineOffline
logic 101 proving negatives

Klarky wrote:
todangst wrote:
As for incoherent declarations (non cognitivism) I do not feel that an incoherent claim is 'false' - an incoherent statement is simpy incoherent, and no truth or falsity can be applied to it in the first place.

Yes that?s a good point, in the example I gave the statement fails due to its incoherency; it being illogical, it doesn't get to the point of qualifying as a universally negative statement. Point taken.

Ok, so it would seem that we can make a categorical universal negative statement if a claim commits an internal contradiction (i.e. "this invisible unicorn is pink" or if a claim is found to be externally contradicted by another fact - i.e. ruled out as per modus tollens. On the other hand, you and I agree that incoherent statements are neither true nor false, but merely 'nonsensical'.

So, are there any other types of universal negative statements?

Those who know the good, do the good. - Socrates

Books on atheism.


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
logic 101 proving negatives

todangst wrote:
Basically, unless you hold to some form of dialetheism (a system of logic that allows for true contraditions)

Dialetheism isn't, in and of itself, a logic. Some Paraconsistent Logician's subscribe to the VIEW of Dialetheism, but thats all it is.

I for one, think Paraconsistent Logic is a fruitful logic. I think a system that can handle contradictions without exploading is interesting. However, I do not subscribe to Dialetheism. I think the LNC holds universally for all propositions.

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Klarky
Klarky's picture
Posts: 70
Joined: 2006-04-10
User is offlineOffline
logic 101 proving negatives

Chaoslord2004 wrote:
Sapient wrote:
Chaos... do you consider saying "no square circles exist" or "no married bachelors exist" is proof that you can prove a negative?

of course.

OK so now i'm getting a bit confused here.

Is the statement "no invisible pink unicorns exist" a universal negative statement or mealy a self-contradictory one, with no justification for further examination or serving as proof of?
If that is what you are saying Todangst then at this point in time, as mentioned, I'm inclined to agree with you.
If it can also be seen as a universal negative statement then does its own formulation serve as its own self evident proof of the proposition it makes, even though it fails to be a coherent proposition?

Chaoslord seems to accept statements of similar quality above as qualifying as a universal negative?

Is Todangst & I in disagreement with Chaoslord regarding these examples? Or Does Chaoslord agree with us but is willing to accept incoherent statements "to see where they go" as an exercise of some sort?
Or, more likely, am I missing the point

Thx for your time and patience.


Chaoslord2004
Chaoslord2004's picture
Posts: 353
Joined: 2006-02-23
User is offlineOffline
logic 101 proving negatives

Klarky wrote:
Is the statement "no invisible pink unicorns exist" a universal negative statement or mealy a self-contradictory one, with no justification for further examination or serving as proof of?

It's a true universal negative statement. The negation of a contradiction, always leads to truth.

Klarky wrote:
If it can also be seen as a universal negative statement then does its own formulation serve as its own self evident proof of the proposition it makes, even though it fails to be a coherent proposition?

Except the proposition "No invisible pink unicorns exist" is coherent. it is percisly because we understand what the proposition means, that we can know it is false.

Klarky wrote:
Chaoslord seems to accept statements of similar quality above as qualifying as a universal negative?

Because it is a universal negative statement. Lets represent the the said proposition in predicate logic, using quantifiers:

∃ = "there exists"

∀ = "For all" or "for any..."

~ = Negation

--> = If...then
a, b, c, d... = Subjects
A, B, C, D... = Predicates
x, y = Variables

Let "no invisible pink unicorns exist" be represented as follows:

~∃x(Ax & Bx), or, ∀x~(Ax & Bx)

This reads: "There does not exist an x, such that x is both pink and invisible." the other one [which is equivolent to the last one] reads: "For all x, it is not the case that x is both pink and invisible"

These are universal negative statements. This should be salient.

Klarky wrote:
Is Todangst & I in disagreement with Chaoslord regarding these examples? Or Does Chaoslord agree with us but is willing to accept incoherent statements "to see where they go" as an exercise of some sort?

And what exactly is incoherent?

Klarky wrote:
Or, more likely, am I missing the point

probably

"In the high school halls, in the shopping malls, conform or be cast out" ~ Rush, from Subdivisions


Da_King_Fish
Da_King_Fish's picture
Posts: 5
Joined: 2006-08-01
User is offlineOffline
logic 101 proving negatives

"There is no universal negation", is to say - there is a universal negation.