Talk:Negative proof

In Appropriate occasions
The statement
 * The law in most democracies also allows negative proofs in criminal cases; namely, a defence lawyer may argue:
 * X is innocent because there is no (or insufficient) proof that X is guilty

This statement assumes that Law, democracies, lawyers, a jury and the judiciary process are, or want to be, logical, and there are countless occasions which they are not logical. Also, a defense lawyer argues that someone is not guilty, which may be better to say in this context.
 * The problem is that they don't claim the opposite is true, the verdict in law is generally 'guilty' or 'not guilty' and rarely described as 'innocent'.  Not guilty just means a threshold of proof wasn't reached to affirm guilt.  — Preceding unsigned comment added by 107.5.105.174 (talk) 09:59, 28 August 2017 (UTC)

Reasons for edits today:
1. The entry (as I found it tonight) falsely claimed that a quote which is popular with researchers -- the quote, “Absence of evidence is not evidence of absence” -- concurs with the "negative proof fallacy" which is detailed on this Wikipedia page, and that this quote, therefore, is also fallacious, according to this past contributor.

Examples herein will be used to prove that history/reality, itself, proves the above saying to be truthful and that the OPPOSITE has been proven fallacious: i.e., someone might not have understood this short-but-tongue-twisting saying, which I will parse below to make sure anyone reading this understands it. The actual fallacy is “Absence of evidence IS evidence of absence” -- which is not only the exact opposite of the saying popular with researchers, but which also tells us that “absence of evidence” is all that’s necessary to prove something non-existent (non-existent="absent") -- not exactly a good model for thorough scientific or logical inquiry, nor consistent with the statement which also is on this page and IS a valid rule of logic: "The reasonable course is to require proof of any statement [not merely a disproof of a contrary statement]".]. Someone modifying this page, not surprisingly, then tried to use “absence of his own evidence” to make fallacious religious/POV statements. Before I cite the POV statements and why they're fallacious...

Here’s an example (logical exercise) which shows WHY it is true ("True" being one antonym of "fallacious") to say, “Absence of evidence is NOT evidence of absence,” but it is fallacious to say the opposite:


 * a. We know today -- thanks to people like a Mr. Franklin, Mr. Tesla, etc. -- that electricity exists (NOTE: “Existence” is an antonym of absence.); and given accounts of lightning causing fires in the years circa 1600, we can reasonably say that electricity also existed in the year 1600 (and that one form of electricity was lightning). No one alive in the year 1600 had proven (i.e., there was an absence of evidence in 1600) much at all regarding electricity, but this absence of evidence from the POV of people in the 1600's does not prove that people in the 1600's would be CORRECT to think that electricity did not exist in the year 1600 (i.e., the aforementioned absence of evidence did NOT produce evidence of absence, or evidence of electricity’s absence from the world or reality).  They would be buying a lie -- that electricity doesn't exist or lighning isn't composed of electricity -- due to an Appeal to Ignorance fallacy if they believed in 1600 that, "Someone just suggested to me that electricity might exist, but it's not proven yet, so it CAN'T exist; they can't even say it "could" exist and be correct!"  i.e. It does NOT follow that “an absence of evidence” produces or exhibits (or “is,” to quote the saying ver batim) “evidence of absence”; thus the correct sentence is: “An absence of evidence is NOT evidence of absence”. This is the tongue-twisting saying in a nutshell.
 * b. Someone postulating, “Electricity MIGHT exist” in the year 1600 wouldn't even be trying to make a logically provable or disprovable statement:
 * Anything "might" exist, but logic (even probabilistic or Bayesian logic) was never intended to address whether “mights” and “maybes” are ‘true’ OR ‘not true’ with 100% certainty -- yet someone's example on this page did try to prove a statement expressed as "could" or "maybe" or with similar words to be logically-fallacious. A claim (i.e. statement) which my opponent qualifies with a “could” (as this page's example used to contain "could" in an alleged example of a "negative-proof fallacy") or a "maybe" is not a claim that can be proven NOR disproven with certainty by Logic, but a "claim" merely of skepticism, i.e. a non-claim, a shrug of the shoulders that his opponent might be correct, but he has not yet seen enough evidence to decide.

To show why the fallacious statement, “absence of evidence IS evidence of absence” is similar to the fallacy which is covered in this Wiki entry, we should compare the two quotes: We can re-state “absence of evidence IS evidence of absence” as substantially the same way as expressing, “This DOES NOT exist (i.e. There IS evidence to prove its absence from reality) because there is no proof that it DOES exist (i.e. because there is absence of evidence showing its existence),”

and,

“This DOES exist because there is no proof that it DOES NOT exist” was the fallacy which I used in the article.

In both quotes above, the one making the claim -- a negative claim (as in trying to "prove the negative") in the first quote, and an affirmative claim in the second quote -- has not proven his claim because there is “no proof” (see the bold text) presented to support EITHER claim above, only disproving of the opponent's claim.

2. Getting back to "the skeptic," I would agree that HE has no burden to "prove the negative" (since he's not even expressing a definitive BELIEF in "the negative," thus he has no interest in proving it; he's taking no stance that this entity must exist [the affirmative] nor that it can't exist [the negative]). But a person who makes his own, definitive claim -- ''e.g., someone living in 1700 who said, “Electricity?! I’m not merely skeptical of that, I say with 100% certainty that it's IMPOSSIBLE that it exists”'' -- is no longer merely “the skeptic”: He's taking a stance: "the negative" stance, or stance that "It doesn't exist" (and in my last quote, he'd be making an Appeal to Ignorance, for reasons that my revisions to the article explain); coupling this "negative" stance to -- as the article said, before I revised some parts -- “The reasonable course is to require proof of any statement,” he now needs to prove his claim...as I think everyone who's contributed to this page in the past would agree, since they all left it in the article...

Trouble is (for him), that he has just claimed a position, claimed that position to be 100% positively true. And it *might* be true, but he CAN'T PROVE his position to be true (because, like any mere mortal, he cannot "prove the negative" despite taking that negative position). If you can't prove your claim to be true, why claim it at all? Why would any *rational* (logical) person claim that something *must* be untrue (or true), when they cannot *rationally* prove it to themselves or others?? Thus, someone making a counter-claim (a speculative statement of an entity’s NON-existence), cannot be expected to prove it since it is "the negative" (again, that much I agree on), but he is not correct-by-default (which someone claimed on this page, which contradicts the quote in the last paragraph). This is consistent with the above quote that everyone left on this page; or to combine that quote with the quote in P2, below, after which I'll deduce the simple conclusion ("C") to these 2 premises):

P1: “The reasonable course is to require proof of any statement”.

P2: No one can “provide proof of a NEGATIVE statement”. (NOTE that this "proof" is "require[d]" by P1, but "No one can 'prove the negative' ").

C: “The reasonable course” is that no logical person should ever make a negative conclusion (i.e. negative "statement," or claim of non-existence) since they cannot give the "require[d] proof" that it does not exist. (There are a few exceptions to this rule, discussed herein, but none seem to apply to the statement posted on this Wiki page, i.e. the statement that one can't even assert "[X, Y, Z, or other supernatural widgets] COULD exist..." because that would be a "fallacy".)

Yet, this contributor HAS stated that a negative conclusion (non-existence of God(s) ) is CERTAINLY true: e.g. by saying others are wrong/fallacious to even say “God MIGHT exist”. This is an argument from ignorance fallacy from himself (not from those he detracts), with -- to quote the Argument_from_Ignorance page -- his "...assertion that if something [here, God or other supernatural things is the "something"] is currently inexplicable to some people, then it...could not... happen, or that if evidence of something has not been scientifically proven to their satisfaction, then it CANNOT exist". [emphasis added, since he dismissd even statements that x "could" exist as "fallacious"] This is uncertainty (as proven in the syllogism above, that one cannot "prove a negative" such as "God definitely doesn't exist") "masquerading as a certainty".

However, I would probbly agree with him, that to not qualify a supernatural existence as “possibly” or “maybe” true, to call it “reasonably” or “probably” true, instead, despite no evidence of that, *is* fallacious, and this is the problem with presenting Creationism or I.Design as a “theory”: It is a mere hypothesis which MIGHT be true, but for which there is no evidence; only someone’s supposition/personal opinion that, “We're too complex to have come into existed any other way than being created”; in this, they have done what some people's militant-Atheism does: ASSume (You know the saying: “It makes an ASS out of you...”) that if you disprove one contrary/competing belief, that your own belief must be true despite a dearth of actual AFFIRMATIVE EVIDENCE supporting your belief.

Even if Franklin et al (returning to that example, but with a new twist), had NOT done any experiments and not proven electricity’s existence (just as there’s no airtight proof of anything supernatural), then we could still postulate, and say -- just as Franklin said postulatively (and CORRECTLY, not “fallaciously”), BEFORE he had flown his kite and gotten some proof by doing so -- that lightning “MIGHT” be electricity, and this statement would not be fallacious ...so long as a word expressing uncertainty, such as “might” or “could” was used to qualify the statement, and so long as someone disagreeing with that statement has not proven another conclusion, which is mutually-exclusive with that postulate, to be true. ...An e.g. to prove this claim is: “Electricity MIGHT exist,” says someone in the year 1600;

and his friend replies: “No, you are certainly wrong; I don’t even accept that you 'could' be correct because there is no proof that it DOES exist (despite that the first guy said it MIGHT exist, not that it DOES exist, and therefore has no burden-of-proof to show that it *does* exist: and therefore we have a Straw Man Fallacy already). I don’t need to PROVE myself right because your failure to PROVE me wrong makes me right (Appeal to Ignorance). And I also don't NEED to prove it because I CANNOT prove it (cannot 'prove the negative'); i.e. I'm allowed to make a statement I can't prove, without proving that statement to be true, because I can't prove it (fallacy: Post Hoc Ergo Propter Hoc/circular).”

...Given what we now understand about the history of electricity, via logical deduction, this latter man’s conclusion is untrue -- untrue is one word synonymous with “fallacious”. The contributor I've noted has said essentially the same thing and used the same fallacious reasoning as the second man in the above example.

So, just as electricity "COULD" have existed in the year 1600 AD (i.e. before anyone *proved* its existence scientifically), it is true that a God or ghosts "COULD" exist even if no proof has not (yet) proven it. This is simple logical-consistency, but the contributor claimed that it is fallacious to even say “There MIGHT be ghosts” (according to Occam’s Razor, he claims, but see number 3, below. However, a religious person also cannot argue that “simply because there is no evidence, a supernatural force DOES exist” instead of saying “COULD exist,” which I reflected in the current Wiki article.  There is no reason in logical-empiricism to state the existence OR non-existence of such thing with any certainty.

3. He also tried to use Occam's Razor to prove his POV correct, so...

Firstly, whether Occam’s Razor is even logically proven (e.g. Chatton, Kant, Leibniz all had Anti-Razors) is debatable, and it is a premise which the author relied upon but never proved to be true (fallacy: False [or Unsubstantiated] Premise).

Secondly, even if we take it as a given that the simplest explanation is true (i.e. that Mr. Ockham was correct -- and this is the spelling of his real name, I'm pretty sure), there is subjectivity about what’s the simplest, most believable conclusion when it comes to "the meaning of life," where we came from, the afterlife, etc. For many people a supernatural force IS the ‘simplest’ answer, which is what the Razor encourages; therefore it was merely this contributor's unproven POV that Creator(s) are not the “simplest” explanation, which was his premise he used to "prove" that they don't exist. If there was no such subjectivity, then nearly everyone (all sane people) would agree on which beliefs are the ‘true’ ones regarding God(s), ghosts, and similar subjects. Objective sciences such as Occam’s Razor or logic are hard to apply to something so subjective as proving OR disproving -- as he tried to do with the Razor -- a supernatural existence.

4. The examples used prior to my modifications tonight, which called it a fallacy to say, “It MIGHT be true that...” (i.e., a completely unproven postulate) can turn out to be TRUE (so long as the above exceptions-to-the-rule don’t exist, of course) -- just as we saw with Franklin proving his postulate to be TRUE by flying a kite -- and these unproven postulates are therefore valuable to science and logic, not contradicted by logic, as calling it a “fallacy” of logic would indicate.

But, what is not constructive in determining the truth, nor is it logical, is to ASSume without evidence, one way OR the other -- as both the contributor and religious zealots do, with this contributor using Circular Reasoning to ‘justify’ why it’s ok for him to make presumptions but not for his opposition to do the same (as exhibited 3 paragraphs above).

Minor changes
I have made some minor changes to the article. Please let me know if there is anything to which you take exception, and why. --JorgeP 15:24, 6 October 2005 (UTC)

Form of negative proof: 'Acceptable' instead of 'existing'?
Shouldnt the form be "X is acceptable because there is no proof that X is unacceptable." instead of "X exists because there is no proof that X doesn't exist.", because the general goal of argumentation is to try to convince a reasonable judge that the standpoint is acceptable. If X is the proposition, the example sentence should be about it's acceptability. The argument in question doesn't necessarily have to do with existence. --JurgenBM 19:01, 30 October 2006 (UTC)


 * because the general goal of argumentation is to try to convince a reasonable judge

yes, in law. change this if you would like. Spencerk 20:02, 30 October 2006 (UTC)

Absence of evidence is not evidence of absence
Regarding "Another form of this kind of fallacious argument is, "Absence of evidence is not evidence of absence!"". This example doesn't meet the criteria of fallacy even it look like. That affirmation is true due of the tautological internal structure of affirmation. Statment doesn't proof anything but isn't false. Compare with "Absence of evidence is evidence of absence!" = fallacy argument. "Evidence - Absence" pair is very tricky some time, compare with "Absence of coin don't means coin absence" that will be fallacy without doubt. Feel 14:18, 10 November 2006 (UTC)


 * I don't think you really understand the phrase. "Absence of evidence is not evidence of absence" is perfectly grammatical and a completely reasonable way of stating the fallacy. Think of it this way: a burglar breaks into your house. The dog scares the burglar away before he can steal anything. The burglar leaves nothing behind, and no trace that he was ever there; but the fact that he left no evidence does not mean that he was never there. Do you understand? It could also be said as "If there is no evidence that something happened, that does not mean that something did not happen".
 * Also, your rephrasing as "absence of coin don't means [sic] coin absence" is misleading, and also incorrect, because it's missing the second "of" that makes the phrase "evidence of absence" different from "absence of evidence". "Coin absence" is equal to "absence of coin". "Evidence absence" is equal to "absence of evidence". "Evidence of absence" is not equal to "absence of evidence". Thefamouseccles 11:55, 2 September 2007 (UTC)

The problem here is the thinking that evidence = proof, if it were, it would correct to say "absence of evidence is not evidence of absence". However, evidence is simply a part of proof. So in the above case of the burglar, absence of evidence, IS evidence of absence, but not proof.

This needs tidying up
It's a confused article.

There is certainly a logical problem with the kind of argument that runs:

1. This cannot be proven to be false C. This is true

As well as

1. This cannot be proven to be true C. This is false

Both are not logically deductive arguments.

Equally, the statement "Absence of evidence is not evidence of absence!" is not logically incorrect, despite being called a fallacy. It is logically possible for something to be existant despite a complete lack of evidence for it being true.

There are of course separate pragmantic arguments as why we should not believe anything that we can't prove. These arguments are, as the article states, scientific, but they are not logical.

The further claim justifying this statement "This is a crucial point of the Scientific method, that before a claim is thought to be true, it must be proven. All claims must be confirmed by observation. If the claim can not be confirmed this way, the belief must not be asserted. Not-knowing is default." is way too biased.

It should at least attribute the view that this is the way beliefs should be formed to someone or some group. It is clear that many people believe that it is acceptable to believe on other grounds, whether faith, or paradigmatic grounds. The idea that all beliefs should be rooted in empirical observation is not the way people live, nor is it wikipedias place to suggest they should (I'm sure a referance to someone or some group that believes they should is fine) - Wight1984

I agree. "This is a crucial point of the Scientific method, that before a claim is thought to be true, it must be proven. All claims must be confirmed by observation. If the claim can not be confirmed this way, the belief must not be asserted. Not-knowing is default." is.../really/ biased, and well beyond wikipedia's mandate. Hewhorulestheworld 09:51, 13 December 2006 (UTC)

I don't agree that 'absence of evidence is not evidence of absence' excludes the possibility of the existence of something for which there is complete lack of evidence. On the contrary, that is the definition of what it proves to be included, and what it proves the fallacy to be seeking improperly to exclude. Anarchangel (talk) 03:54, 22 November 2008 (UTC)

Tidying up
I've tried to make this article more coherent and logical by editing and removing some excessive text. I hope those who would like to help completing this article will assure these aspects as well. JurgenBM 13:40, 28 December 2006 (UTC)

Not a Real Law of Logic
1. If "You can't prove a negative" is true then you just proved a negative making it at the same time false.

2. If "You can't prove a negative" is false than there is no problems.

3. A real law of logic, the law of non-contradiction, is something can not be true and false, so the only logical answer would be to say it's false. Q.E.D. http://en.wikipedia.org/wiki/Law_of_noncontradiction If you put this in, as maybe arguments against find a better source, it bad when you source wikipedia in wikipedia.

I like to point out to my friends that this is the fallacy that "justified" the Iraq war. —Preceding unsigned comment added by 69.15.30.119 (talk) 15:34, August 30, 2007 (UTC)


 * I'm not sure if that is true, I believe the justification for going to war with Iraq was "Iraq has WMD" which is a positive, which has since been virtually proved to be false, I say virtually because the "absence of evidence, isn't evidence of absence", although that statement is in itself a negative and this fallacy,"absence of evidence, isn't evidence of absence", has been discussed in more detail above.

Assuming infinite knowledge, or all knowledge of a finite subject?
Wouldn't it be possible to prove a negative if all elements of the statement were known? Say, for example, a list of names. 'John' is either on the list or not. So if you say, 'There is no evidence that John is on the list, therefore John is not on the list', that is correct, no? Making the inherent problem one of lack of knowledge, not of impossibility. Or is that example excluded from Negative Proof by some property or rule of it that isn't mentioned? Anarchangel (talk) 03:54, 22 November 2008 (UTC)

Reconsideration of "Applying the Fallacy"
First, let me make my biases clear and preface this by saying that I believe humans have definitely contributed to the increase in global temperatures (global warming) in recent years. That said, I do not find the "Applying the Fallacy" section to be appropriate for this article. Specifically, I feel this section of the article does not adhere to Wikipedia's "neutral point of view" core policy, particularly the "Let the facts speak for themselves", and "substantiating biased statements" sections.

I take no issue with this section until about mid-way through, when burden of proof shifts to Team 2. In particular, the phrase, "all the data tells us that global warming is real," is neither attributed to any credible source nor backed by any data to support it. In fact, the entire section is without any citations or data of any kind; it simply presents global warming as a generally accepted fact, which it is not. In actuality, global warming remains a highly-contested issue. Although you certainly could revise this section to have a more neutral tone, such as by providing sources and data that support the existence global warming, there is too much dispute and uncertainty about global warming to make it an acceptable example for this article. --Frito31382 (talk) 05:28, 19 February 2009 (UTC)

Redirect to Argument from ignorance.
I've acted boldly and redirected to Argument from Ignorance. I have never seen any mention of Negative Proof in philosophical logic or critical thinking texts and nothing in the article serves to distinguish this fallacy from Argument from Ignorance. Thus, readers are better served with a redirect. Phiwum (talk) 13:35, 19 February 2009 (UTC)

Some time ago, Anarchangel reverted my redirect with the following comment:


 * Argument from ignorance finds proof in lack of proof; negative proof finds proof in lack of evidence. One is concerned with process, the other with situation. See talk.

I find this explanation utterly spurious. As a logician and teacher of courses in critical thinking, I have never seen a distinction between lack of proof and lack of evidence and I have never seen argument from ignorance presented in such a way that the latter condition is excluded. Furthermore, I have never seen the term negative proof in any text on critical thinking, logic or rhetoric.

Note as well that the references themselves lack a single citation of a logician, rhetorician or other credible individual discussing "negative proofs". The sole citation (safalra.com) that uses the term fails RS.

Finally, we note that the text itself refutes Anarchangel's claimed distinction. The article clearly states, "It is asserted that a proposition is true, only because it has not been proven false." Hence, we find no clear difference between negative proof and argument from ignorance and we have no evidence the former term has any widespread usage.

Consequently, I have restored the redirect. Phiwum (talk) 20:48, 20 September 2009 (UTC)