proving a negative

[petesampras]

Certain negatives cannot be disproved, such as "God does not exist".

However, somehow, on these forums, this has been twisted into the idea that you can never prove a negative - hence demands to prove a negative are met with hostility.

I'd be interested to know what, exactly, people mean when they say - "you can't prove a negative". As far as I can see it is possible, and depends on the particular statement.

e.g.

"hhhhjjjj"

Above string of text does NOT contain an 'e'.

That's a negative, and it can be proved - in so far as anything can be proven.

[Knife]

How do we know? There might be an 'e' there in super small text that we can't see. What we can see does not contain an 'e' so we make the conclusion that there isn't an 'e' there. But I can't prove it.

That's what 'can't prove a negitive' means. You can only 'prove' what is there and then make assumptions and conclusions based on that.

[Feil]

Search function is your friend.

The issue isn't that a negative cannot be proved. The issue that the scientific method assumes a default negative in regards to any hypothesis, theory, etc, and therefore the burden of proof lies in the positive.

Demanding that someone prove the negative isn't asking them to do the impossible, but it is shifting the burden of proof, which is dishonest debating, which is not tolerated here.

[petesampras]

How do we know? There might be an 'e' there in super small text that we can't see. What we can see does not contain an 'e' so we make the conclusion that there isn't an 'e' there. But I can't prove it.

That's what 'can't prove a negitive' means. You can only 'prove' what is there and then make assumptions and conclusions based on that.

Ok, but if we change the statement to "there is not an 'e' in the default forum text in the above string" it is provable.

[Feil]

Blah. Double post.

How do we know? There might be an 'e' there in super small text that we can't see. What we can see does not contain an 'e' so we make the conclusion that there isn't an 'e' there. But I can't prove it.

That's what 'can't prove a negitive' means. You can only 'prove' what is there and then make assumptions and conclusions based on that.

You can prove it as much as you can prove anything--by stating a premise that everyone agrees upon and making a logical argument from that premise to show that a->b.

Premise: if there is an e in that string, I will be able to see it.
I cannot see an e in that string.
Therefore there is no e in that string.

You can dispute the premise, but not the logic. We could use any number of premises--we could copy the string to a simpletext application, or we could define the letter e in terms of being visible to the naked eye.

[petesampras]

Search function is your friend.

The issue isn't that a negative cannot be proved. The issue that the scientific method assumes a default negative in regards to any hypothesis, theory, etc, and therefore the burden of proof lies in the positive.

Demanding that someone prove the negative isn't asking them to do the impossible, but it is shifting the burden of proof, which is dishonest debating, which is not tolerated here.

That makes sense, but the counter argument often given is "you can't prove a negative" which is different from "the burden of proof is on you".

Furthermore, I would ask what is meant by default negative or positive in terms of a hypothesis.

"Apples are invisible" - consider that as a hypothesis.

So we assume it is false until proven true. Therefore we are assuming that "it is not the case that apples are invisible".

But what about the hypothesis that - "apples are visible"? Following the same reasoning we end up with conflicting base assumptions.

It seems more reasonable to say, in this example, that apples may or may not be invisible until evidence is provided. You can't simultaneously shift the burden of proof on both hypothesis's.

I'll take a look at the link you provided, so apologies if this is already covered there.

[Darth Wong]

That makes sense, but the counter argument often given is "you can't prove a negative" which is different from "the burden of proof is on you".

The fact that people don't go to the bother of explaining the entire rationale behind Occam's Razor every time some idiot asks for proof of his favourite negative does not mean it is OK to make a claim as long as it cannot be proven false.

Furthermore, I would ask what is meant by default negative or positive in terms of a hypothesis.

"Apples are invisible" - consider that as a hypothesis.

See Occam's Razor. It has to do with existence of terms. In this case, you are saying that there are two totally unnecesary terms: an apple which we can't see, and a property of invisibility which we cannot test. The empty space before us can be easily explained without either of those terms, hence they are bullshit and if you say "but you can't prove it's not there", you're being an idiot.

So we assume it is false until proven true. Therefore we are assuming that "it is not the case that apples are invisible".

But what about the hypothesis that - "apples are visible"? Following the same reasoning we end up with conflicting base assumptions.

That's because you have a childlike understanding of the concept. The same reasoning yields a totally different conclusion in this case. The apple is necessary in order to explain the fact that we see an apple in front of us.

It seems more reasonable to say, in this example, that apples may or may not be invisible until evidence is provided. You can't simultaneously shift the burden of proof on both hypothesis's.

Are you honestly so dense that you don't understand the connection between hypothesis and observation? You make a hypothesis to explain an observation. You do NOT make a hypothesis out of thin air and then declare that people have to prove it's false.

[Rye]

Certain negatives cannot be disproved, such as "God does not exist".

Depends on the god. There are lots of gods that are potentially falsifiable, internally contradictory, etc.

I'd be interested to know what, exactly, people mean when they say - "you can't prove a negative". As far as I can see it is possible, and depends on the particular statement.

Heheh...

A "You can't prove a negative."

B "You can't prove that! Stop throwing unprovable slogans at me!"

It seems more reasonable to say, in this example, that apples may or may not be invisible until evidence is provided.

As if it does! That sort of reasoning applies to the intangible rapist rugby team that raped your arse for proposing such nonsense. "Oh, well I may or may not have been raped by an intangible rugby team, I must wait for evidence either way before I commit to a conclusion!!"

I could say "God isn't real and there's no such thing as revealed knowledge," and people demand proof, I just point out that imagination accounts for all those things. Given that, why would we conclude something is real when it's apparently imaginary? If we start doing that, why don't we do it for the antigod or deicidal dragons? If you're undecided, what do you not find particularly realistic about the concepts I'm declaring are imaginary? Etc.

[Darth Wong]

I think some people believe that "negative" in this context means "untrue", so any side of a hypothesis is either true or untrue depending on how you phrase it, hence you can't tell which way the "negative" goes. Of course, that's because they're mutilating the argument based on its choice of word, which is retarded. If you realize that "negative" in this context means "does not exist" or "is not relevant", then it becomes more obvious why you can't demand that people prove it.

[petesampras]

That makes sense, but the counter argument often given is "you can't prove a negative" which is different from "the burden of proof is on you".

The fact that people don't go to the bother of explaining the entire rationale behind Occam's Razor every time some idiot asks for proof of his favourite negative does not mean it is OK to make a claim as long as it cannot be proven false.

Furthermore, I would ask what is meant by default negative or positive in terms of a hypothesis.

"Apples are invisible" - consider that as a hypothesis.

See Occam's Razor. It has to do with existence of terms. In this case, you are saying that there are two totally unnecesary terms: an apple which we can't see, and a property of invisibility which we cannot test. The empty space before us can be easily explained without either of those terms, hence they are bullshit and if you say "but you can't prove it's not there", you're being an idiot.

So we assume it is false until proven true. Therefore we are assuming that "it is not the case that apples are invisible".

But what about the hypothesis that - "apples are visible"? Following the same reasoning we end up with conflicting base assumptions.

That's because you have a childlike understanding of the concept. The same reasoning yields a totally different conclusion in this case. The apple is necessary in order to explain the fact that we see an apple in front of us.

It seems more reasonable to say, in this example, that apples may or may not be invisible until evidence is provided. You can't simultaneously shift the burden of proof on both hypothesis's.

Are you honestly so dense that you don't understand the connection between hypothesis and observation? You make a hypothesis to explain an observation. You do NOT make a hypothesis out of thin air and then declare that people have to prove it's false.

In the example given of the hypotheses "apples are visible" and "apples are invisible" I was intending for a situation where apples are known to exist but had never been seen. I'm not talking about a situation where apples may or may not exist and may or may not be invisible. Say that we know that apples can exist from examining apple trees out of season and concluding it, but we have no idea whether they will be invisible or visible. The only unknown here is the visibility or invisibility of apples, not whether they can exist. In that situation the two hypotheses are negations of each other, and that is the type of situation I am refering to. Both contain equal numbers of unknowns, so occams razor has nothing to say. Taking the assumption that a hypothesis is assumed false until demonstrated true leads to a contradiction in this case.

[General Zod]

In the example given of the hypotheses "apples are visible" and "apples are invisible" I was intending for a situation where apples are known to exist but had never been seen. I'm not talking about a situation where apples may or may not exist and may or may not be invisible. Say that we know that apples can exist from examining apple trees out of season and concluding it, but we have no idea whether they will be invisible or visible. The only unknown here is the visibility or invisibility of apples, not whether they can exist. In that situation the two hypotheses are negations of each other, and that is the type of situation I am refering to. Both contain equal numbers of unknowns, so occams razor has nothing to say. Taking the assumption that a hypothesis is assumed false until demonstrated true leads to a contradiction in this case.

If you can't observe or quantify the hypothesis, then it's not a very useful one and a lot harder to prove or disprove. As long as there's other factors you can test for besides whether or not you can see something, then it can be worked with. An invisible apple should still have weight, substance, and taste to it, along with specific chemical properties.

[Feil]

I'm not talking about a situation where apples may or may not exist and may or may not be invisible.

You were a few minutes ago. "It seems more reasonable to say, in this example, that apples may or may not be invisible until evidence is provided. "

Say that we know that apples can exist from examining apple trees out of season and concluding it,

Ever lived near apple trees? Apples don't just magically disappear when they aren't in season.

but we have no idea whether they will be invisible or visible.

Except that we know what the apples are made of (since there's no nuclear chemistry going on and matter is conserved) and that everything they are made of is very visible.

The only unknown here is the visibility or invisibility of apples, not whether they can exist.

But I'll accept this anyway, for the sake of argument.

In that situation the two hypotheses are negations of each other, and that is the type of situation I am refering to.

Except they aren't hypotheses, because they don't explain data. A datum is not a hypothesis. Making the datum speculative doesn't make it any more of a hypothesis.

Both contain equal numbers of unknowns, so occams razor has nothing to say.

Invisibility is not known to exist (even transparent substances diffract light and impede it), so Occam's Razor has plenty to say.

Taking the assumption that a hypothesis is assumed false until demonstrated true leads to a contradiction in this case.

I think some people believe that "negative" in this context means "untrue", so any side of a hypothesis is either true or untrue depending on how you phrase it, hence you can't tell which way the "negative" goes. Of course, that's because they're mutilating the argument based on its choice of word, which is retarded. If you realize that "negative" in this context means "does not exist" or "is not relevant", then it becomes more obvious why you can't demand that people prove it.

[petesampras]

In the example given of the hypotheses "apples are visible" and "apples are invisible" I was intending for a situation where apples are known to exist but had never been seen. I'm not talking about a situation where apples may or may not exist and may or may not be invisible. Say that we know that apples can exist from examining apple trees out of season and concluding it, but we have no idea whether they will be invisible or visible. The only unknown here is the visibility or invisibility of apples, not whether they can exist. In that situation the two hypotheses are negations of each other, and that is the type of situation I am refering to. Both contain equal numbers of unknowns, so occams razor has nothing to say. Taking the assumption that a hypothesis is assumed false until demonstrated true leads to a contradiction in this case.

If you can't observe or quantify the hypothesis, then it's not a very useful one and a lot harder to prove or disprove. As long as there's other factors you can test for besides whether or not you can see something, then it can be worked with. An invisible apple should still have weight, substance, and taste to it, along with specific chemical properties.

To be honest invisible and visible was a poor choice of characteristics to illustrate the point. Imagine a world where all objects were either Green or Yellow in colour. Now in this world we know apples exist and will all have the same colour, but have never seen one. From examining apple trees it may be possible to predict the colour of apples. We can come up with two hypotheses here for our investigation. "Apples will be Yellow" and "Apples will be Green". Going on the rule suggested earlier that a hypothesis is assumed false until evidence is provided to suggest that it is true leads to a contradiction.

[Wyrm]

In my experience, all statements that you would use "you can't prove a negative" on all tend to be negative existential statements, which can be recast as a positive universal statement (and vice versa). "There is no God" is a negative statement on the existence of an instance of God, or to recast as a universal statement, "All things that exist are not God." Conversely, "All crows are black," which can be cast into "There is no non-black crow," is a negative statement on the existence of non-black crows. It is completely unreasonable for every thing that exists to be examined for Godlihood, and to find all crows that exist and find them to all be black. Therefore, neither proposition can be proven with 100% certainty, with one caveat: if the way you define 'God' can be proven to preclude him from existence, then you can indeed prove that there is no God, because the object with the required properties automatically means that the object does not exist. Going back to the crows, if you define a 'crow' as a necessarily black thing, then all crows are indeed black, because any non-black object is just not a crow (even if it is otherwise crowlike).

On the other hand, proving that there is a God is conceptually a far easier task: just present a being who proceeds to demonstrate the required properties. All it takes to prove that there exists a non-black crow is to present a creature that is non-black but otherwise crowlike (respecting the final caveat in the last paragraph). We can even prove the existence of objects we never seen by the consequences that their non-existence would entail, such as the neutrino being predicted because otherwise beta decay would not universally preserve energy and momentum.

The flip side of the coin is that although a negative cannot be proved, it can be strongly undermined. If you go out and make a worldwide survey of crows, collecting a large random sample of crows, then a non-white crow, if it exists has a fair chance of making it into our sample, and therefore demonstrate its existence and disproving our assertion that there is no non-black crow. That we don't find this crow dispite our efforts indicates that "There exists a non-black crow" is greatly undermined and its logical opposite, "All crows are black," to be strongly confirmed. Therefore, positing a non-black crow (even if he exists) is an unnecessary complication of an already strongly confirmed hypothesis about crows.

In the example given of the hypotheses "apples are visible" and "apples are invisible" I was intending for a situation where apples are known to exist but had never been seen.

If they're known to exist, even if they are never seen, apples nonetheless interact with the natural world in specific ways. As opposed to things that don't interact with the natural world at all, the largest class of which are the non-existent objects. If we know apples to exist, then they leave evidence that they do exist, because leaving a body of evidence consistent with their existence is a prerequisite to our knowing of their existence.

I'm not talking about a situation where apples may or may not exist and may or may not be invisible. Say that we know that apples can exist from examining apple trees out of season and concluding it, but we have no idea whether they will be invisible or visible.

We can gather from this strong evidence that apples are fruit, and should therefore have some characteristics in common with other fruit, such as visibility.

The only unknown here is the visibility or invisibility of apples, not whether they can exist. In that situation the two hypotheses are negations of each other, and that is the type of situation I am refering to. Both contain equal numbers of unknowns, so occams razor has nothing to say.

Wrong. Since we know that apples are probably fruit, they are likely made out of plant matter, which we have no known invisible examples thereof. Therefore, to hypothesize that apples are invisible introduces the unnecessary term of presently undiscovered invisible plant matter. So Occam's razor cuts invisible apples away.

[Wyrm]

GHETTO EDIT:

The flip side of the coin is that although a negative cannot be proved, it can be strongly undermined.

Bleah, "Confirmed"!

[General Zod]

To be honest invisible and visible was a poor choice of characteristics to illustrate the point. Imagine a world where all objects were either Green or Yellow in colour. Now in this world we know apples exist and will all have the same colour, but have never seen one. From examining apple trees it may be possible to predict the colour of apples. We can come up with two hypotheses here for our investigation. "Apples will be Yellow" and "Apples will be Green". Going on the rule suggested earlier that a hypothesis is assumed false until evidence is provided to suggest that it is true leads to a contradiction.

There's a gaping problem in your reasoning though. How do you know something exists if you only have one vague criteria to judge it by that can fit so many other things? Parsimony would rule out its existence more than anything due because of the lack of evidence supporting it, and such a horribly vague description.

[petesampras]

To be honest invisible and visible was a poor choice of characteristics to illustrate the point. Imagine a world where all objects were either Green or Yellow in colour. Now in this world we know apples exist and will all have the same colour, but have never seen one. From examining apple trees it may be possible to predict the colour of apples. We can come up with two hypotheses here for our investigation. "Apples will be Yellow" and "Apples will be Green". Going on the rule suggested earlier that a hypothesis is assumed false until evidence is provided to suggest that it is true leads to a contradiction.

There's a gaping problem in your reasoning though. How do you know something exists if you only have one vague criteria to judge it by that can fit so many other things? Parsimony would rule out its existence more than anything due because of the lack of evidence supporting it, and such a horribly vague description.

We can know that things exist, or will likely exist at some point, without directly observing them. In this case we have trees which we have analysed and predicted will grow some form of fruit. This fruit we have decided to call apples, but we don't yet have any idea which of the two colours it will be.

[General Zod]

We can know that things exist, or will likely exist at some point, without directly observing them. In this case we have trees which we have analysed and predicted will grow some form of fruit. This fruit we have decided to call apples, but we don't yet have any idea which of the two colours it will be.

We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses.

[petesampras]

We can know that things exist, or will likely exist at some point, without directly observing them. In this case we have trees which we have analysed and predicted will grow some form of fruit. This fruit we have decided to call apples, but we don't yet have any idea which of the two colours it will be.

We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses.

Sorry, I disagree strongly with you here. If we find a new type of fruit, we can predict there will exist a new species of plant which gave rise to it. This is not guessing, it is predictions based on our understanding of how the world functions.

In the above example we have observations drawn from analysing this species of tree. It is perfectly feasible to have a situation where you would be able to predict that a plant will bare fruit without actually observing the fruit.

[General Zod]

We can know that things exist, or will likely exist at some point, without directly observing them. In this case we have trees which we have analysed and predicted will grow some form of fruit. This fruit we have decided to call apples, but we don't yet have any idea which of the two colours it will be.

We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses.

Sorry, I disagree strongly with you here. If we find a new type of fruit, we can predict there will exist a new species of plant which gave rise to it. This is not guessing, it is predictions based on our understanding of how the world functions.

In the above example we have observations drawn from analysing this species of tree. It is perfectly feasible to have a situation where you would be able to predict that a plant will bare fruit without actually observing the fruit.

I'm not exactly sure how this disagrees with my claim that you can't know something without observations to back a hypothesis up. As long as a hypothesis can be independently reproduced and verified, then there's no need for everyone to make a direct observation in order to know something. . .

[petesampras]

I'm not exactly sure how this disagrees with my claim that you can't know something without observations to back a hypothesis up. As long as a hypothesis can be independently reproduced and verified, then there's no need for everyone to make a direct observation in order to know something. . .

You said - "We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses."

Which was said in the context of my assertion that we could know that a fruit will exist at some point without ever observing it. I gave an example of how you could know something exists without directly observing it. If you see a flaw in this example can you point it out. To me it implies that we can know that something exists without directly observing it.

[General Zod]

I'm not exactly sure how this disagrees with my claim that you can't know something without observations to back a hypothesis up. As long as a hypothesis can be independently reproduced and verified, then there's no need for everyone to make a direct observation in order to know something. . .

You said - "We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses."

Which was said in the context of my assertion that we could know that a fruit will exist at some point without ever observing it. I gave an example of how you could know something exists without directly observing it. If you see a flaw in this example can you point it out. To me it implies that we can know that something exists without directly observing it.

I never said they had to be directly observed, you did. The key is whether or not it can be independently verified, which I added in my next post.

[petesampras]

I'm not exactly sure how this disagrees with my claim that you can't know something without observations to back a hypothesis up. As long as a hypothesis can be independently reproduced and verified, then there's no need for everyone to make a direct observation in order to know something. . .

You said - "We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses."

Which was said in the context of my assertion that we could know that a fruit will exist at some point without ever observing it. I gave an example of how you could know something exists without directly observing it. If you see a flaw in this example can you point it out. To me it implies that we can know that something exists without directly observing it.

I never said they had to be directly observed, you did. The key is whether or not it can be independently verified, which I added in my next post.

Right, so in the context of the original point of mine which you objected to. What is your objection to the possibility of knowing that a type of fruit will exist at some point without directly observing it? It can be verified by analysing the tree and concluding that it will produce fruit. If you have no objection to this idea, then I'm not sure exactly what your objection is to the argument.

[General Zod]

I'm not exactly sure how this disagrees with my claim that you can't know something without observations to back a hypothesis up. As long as a hypothesis can be independently reproduced and verified, then there's no need for everyone to make a direct observation in order to know something. . .

You said - "We can guess that something might exist, but without observations to back up those hypothesis, that's all they are. Guesses."

Which was said in the context of my assertion that we could know that a fruit will exist at some point without ever observing it. I gave an example of how you could know something exists without directly observing it. If you see a flaw in this example can you point it out. To me it implies that we can know that something exists without directly observing it.

I never said they had to be directly observed, you did. The key is whether or not it can be independently verified, which I added in my next post.

Ghetto edit: In other words, as long as someone can repeat the observations when they know the information that someone else directly observed, then direct observation is not necessary as long as someone somewhere has done so and given sufficient information to determine what the exact object is by someone who's never seen it.

[General Zod]

Right, so in the context of the original point of mine which you objected to. What is your objection to the possibility of knowing that a type of fruit will exist at some point without directly observing it? It can be verified by analysing the tree and concluding that it will produce fruit. If you have no objection to this idea, then I'm not sure exactly what your objection is to the argument.

My problem is that you keep saying we can't know something without observing it, and then switching that with directly observing it. As long as someone somewhere has observed it directly and written down enough information, then we don't need to observe it directly ourselves as long as it can be independently verified. But somebody needs to have observed it at least once, or it goes back to my original problem with your claims. That you cannot know something without observations to back that knowledge up.