Argument from ignorance

Cogito ergo sum
Logic and rhetoric

Key articles

* Logical fallacy
* Syllogism
* Argument

General logic

* Argument by assertion
* Bulverism
* Shoehorning
* Coincidence
* List of cognitive biases
* Sunk cost

Bad logic

* Overgeneralization
* Flying carpet fallacy
* Appeal to gravity
* Association fallacy
* Evidência suprimida
* Tontería

v \- t \- e

Not just a river in Egypt
Denialism

Alternative facts

* Cornucopian vs. Malthusian debate
* Clean coal
* Holocaust denial
* Feathered dinosaurs
* Uyghur genocide
* China apologetics

♫ We're not listening ♫

* Christine Maggiore
* B.o.B
* S. Fred Singer
* Marc Morano
* Joseph Stalin
* Candace Owens

v \- t \- e

Not to be confused with negative evidence, which is where there is no evidence for something when there should be.

“”The very lack of evidence is thus treated as evidence; the absence of smoke proves that the fire is very carefully hidden.

—C.S. Lewis (in a glimpse of clarity)[1]

The argument from ignorance (or argumentum ad ignorantiam and negative proof) is a logical fallacy that claims the truth of a premise is based on the fact that it has not (yet) been proven false or that a premise is false because it has not (yet) been proven true. This is often phrased as "absence of evidence is not evidence of absence".

This can be seen as somewhat related to cherry-picking: Someone will point out something in particular about anything topical which is not easy to immediately explain. A viewer with no experience nor expertise on the subject matter might be unable to come up with an explanation or to identify the artifact/phenomenon. The individual then abuses this to claim that the unexplained artifact or phenomenon is evidence of a particular theory. The lack of a counterargument for the theory does not mean the theory is necessarily correct — that is the fallacy the individual is guilty of.

If the only evidence for something's existence is a lack of evidence for it not existing, then the default position is one of mild skepticism and not credulity. The reason for this is that one is making an extraordinary claim by asserting its existence, and extraordinary claims require extraordinary evidence. This type of negative proof is common because it is used as an attempt to shift the burden of proof onto the skeptic rather than the proponent of the idea. The burden of proof is on the individual proposing existence, not the one questioning existence.

## Contents

* 1 Form
* 2 Incomplete information
* 3 Variations
* 4 Examples
* 5 Retort
* 6 When proof is presented
* 7 Negative evidence
* 8 See also
* 9 External links
* 10 References

## Form[edit]

X is true because there is no proof that X is false.

You do not know what X is. Therefore we do.

## Incomplete information[edit]

This argument is not always the same as negative proof: if there is relevant information missing, an accurate judgement may not be possible.[2] Some people were found to treat missing information as a positive, as a negative, or as "average". A critical thinker needs to analyse the evidence to determine what relevant information is missing, and whether what is missing is significant, or may be at risk of confirmation bias. When key information is missing, normally the result should be lower confidence in judgement and less extreme judgement. Kardes and Posavac found individuals who know more about a subject were found to be more sensitive to recognizing omissions, and developed better and more appropriate judgements.[2]

## Variations[edit]

Another form that this fallacy can take is the form that of an argument from incredulity (also known as argument from personal belief or argument from personal conviction), which is that one's personal incredulity or credulity towards a premise is a logical reason for acceptance or rejection. This incredulity can stem from ignorance (defined as a lack of knowledge and experience) or from willful ignorance (defined as a flat-out refusal to gain the knowledge). The concept of irreducible complexity is based entirely around this idea of personal incredulity.

## Examples[edit]

For example, if you accuse a person of a wrongdoing, it is up to you to prove it. It is an argument from ignorance to suggest someone is guilty because they can't prove their innocence. For example, "Andrew can't prove he didn't eat the last jellybean, therefore he must have eaten it".

Almost all the claims from the anti-science movement revolve around some form of personal incredulity or argument from ignorance.

Proponents of the anti-science movement will usually pick some aspect of a currently accepted scientific theory and argue that it must be wrong because they do not believe it explains some aspect of the natural world. Common examples of this are such claims as "you can't prove global warming is caused by humans", "I don't see how evolution could increase the complexity of an organism", "material properties of the brain cannot presently explicitly explain consciousness, so it must be caused by non-materialist processes", or "I don't know how this alternative medicine works, but it does".

The significance of missing information is often represented in scientific publications using the confidence interval (CI). A confidence interval of 0.6 to 1.6 means a wide range of effects, from a 40% reduction to a 60% increase.[3] When the Department of Health and Human Services dropped its recommendation of regular flossing, it cited a Cochrane Review that reported only "very unreliable" evidence of the benefits of flossing because there were no adequate controlled trials. The New York Times ran the headline "Feeling Guilty About Flossing? Maybe There's No Need".[4] The lack of confirmatory evidence was wrongly taken as evidence against flossing, but people with a different confirmation bias may make the opposite interpretation.[4]

## Retort[edit]

“”Ignorance is ignorance; no right to believe anything can be derived from it. In other matters no sensible person will behave so irresponsibly or rest content with such feeble grounds for his opinions and for the line he takes.

—Sigmund Freud, The Future of an Illusion[5]

A common retort to a negative proof is to propose a query about the existence of another thing that has no proof as valid. This is similar to reductio ad absurdum, that taking negative proof as legitimate means that one can prove practically anything, regardless of how absurd.

A religious apologist using the argument from ignorance would state something like, "the existence of God is true because there is no proof that the existence of God is false". But a counter-apologist can use that same "argument" to state, "the nonexistence of God is true because there is no proof that the nonexistence of God is false". This immediately demonstrates how absurd the argument from ignorance is by turning the tables on those who use this ~~"argument"~~ fallacy, like some religious apologists.

It is possible to show formally that absence of evidence is, in fact, evidence of absence, though weaker than actual counter-evidence. In probability theory, if  P ( H | E ) > P ( H ) {\displaystyle P(H|E)>P(H)} (observing event E makes hypothesis H more likely), then, necessarily,  P ( H | ¬ E ) < P ( H ) {\displaystyle P(H|\neg E)<P(H)} (failure to observe event E makes hypothesis H less likely).[6]

Proof

Let H be the hypothesis and E the evidence, and assume  P ( H | E ) > P ( H ) {\displaystyle P(H|E)>P(H)} . By the law of total probability, and since  P ( E ) + P ( ¬ E ) = 1 {\displaystyle P(E)+P(\neg E)=1} ,

P ( H ) = P ( H | E ) P ( E ) + P ( H | ¬ E ) P ( ¬ E ) = P ( H | E ) P ( E ) + P ( H | ¬ E ) ( 1 − P ( E ) ) > P ( H ) P ( E ) + P ( H | ¬ E ) ( 1 − P ( E ) ) {\displaystyle P(H)=P(H|E)P(E)+P(H|\neg E)P(\neg E)=P(H|E)P(E)+P(H|\neg E)(1-P(E))>P(H)P(E)+P(H|\neg E)(1-P(E))}

Therefore,

P ( H ) ( 1 − P ( E ) ) > P ( H | ¬ E ) ( 1 − P ( E ) ) {\displaystyle P(H)(1-P(E))>P(H|\neg E)(1-P(E))}

and dividing by  1 − P ( E ) {\displaystyle 1-P(E)} , which is positive,

P ( H ) > P ( H | ¬ E ) {\displaystyle P(H)>P(H|\neg E)}

QED.

Therefore:

* If a series of well-timed sabotages throughout the country would be evidence for a network of spies infiltrating it, then if no sabotages occur, that, by itself, is evidence of no such network existing (as opposed to evidence of the spies existing but biding their time).
* If observable divine miracles would be evidence for God's existence, then lack of observable divine miracles is, by itself, evidence against it.

## When proof is presented[edit]

One important element to remember in regards to negative proof is that once positive evidence has been presented, the burden shifts to the skeptic to refute the evidence presented. One cannot keep arguing from the position of "negative proof" after the presentation of valid evidence. This point, however, is completely lost on most creationists (such as intelligent design advocates), who shout from the rooftops that there are no transitional fossils long after they've been repeatedly shown them. Confirmation bias, anyone?

## Negative evidence[edit]

See the main article on this topic: Negative evidence

A common saying in pseudologic is "You can't prove a negative." This is, as the hatnote up top says, simply not true. This is clearly not true because any statement can be rewritten into the negation of its negation. Any provable statement can be written as a negative. For example, "X is true" can be rewritten as "X is not false", a negative statement! If "X is true" can be proven true, then you have also proven a negative statement "X is not false".

Karl Popper applied the concept of falsifiability to judge what is unscientific, using the example of Russell's teapot. Popper stated that what is unfalsifiable is unscientific, and it is pseudoscience to declare an unfalsifiable theory to be true.[4]

## See also[edit]

* Extraordinary claims require extraordinary evidence
* God of the gaps
* Russell's Teapot
* Science doesn't know everything
* Young Earth creationism

## External links[edit]

* The Throne of Heaven (a SFW comic on an NSFW website)

## References[edit]

1. ↑ The Four Loves (1960), pp. 61, 62-63 Excerpt
2. ↑ 2.0 2.1 Ellis, G. (2018). pp. 116
3. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC351831/
4. ↑ 4.0 4.1 4.2 Bonchek (2016). Absence of Evidence is not Evidence of Absence
5. ↑ The Future of an Illusion, part VI.
6. ↑ Absence of Evidence Is Evidence of Absence, Eliezer Yudkowsky

v \- t \- e

Articles about logical fallacies

Informal fallacies: |  Appeal to tradition • Appeal to novelty • Appeal to nature • Argument from morality • Argumentum ad martyrdom • Big words • Certum est quia impossibile est • Morton's fork • Friend argument • Exception that proves the rule • Extended analogy • Hindsight bias • Race card • Moralistic fallacy • Release the data • Gish Gallop • Terrorism-baiting • Uncertainty tactic • Greece-baiting • Ham Hightail • Red-baiting • Gore's Law • Nazi analogies • Mistaking the map for the territory • Red herring • Quidquid latine dictum sit, altum videtur • Presentism • Sunk cost • Two wrongs make a right • Flying carpet fallacy • My enemy's enemy • Appeal to ancient wisdom • Danth's Law • Argumentum ad lunam • Balance fallacy • Golden hammer • Loaded question • Escape to the future • Word magic • Spider-Man fallacy • Sanctioning the devil • Appeal to mystery • Informal fallacy • Common sense • Post-designation • Hyperbole • Relativist fallacy • Due diligence • Straw man • Good old days • Appeal to probability • Infinite regress • Circular reasoning • Media was wrong before • Is–ought problem • Ad iram • Just asking questions • Pink-baiting • Appeal to faith • Appeal to fear • Appeal to bias • Appeal to confidence • Appeal to consequences • Appeal to emotion • Appeal to flattery • Appeal to gravity • Appeal to hate • Argument from omniscience • Argument from silence • Argumentum ad baculum • Argumentum ad fastidium • Association fallacy • Broken window fallacy • Category mistake • Confounding factor • Counterfactual fallacy • Courtier's Reply • Damning with faint praise • Definitional fallacies • Equivocation • Fallacy of accent • Fallacy of accident • Fallacy of amphiboly • Gambler's fallacy • Imprecision fallacy • Moving the goalposts • Nirvana fallacy • Overprecision • Pathos gambit • Pragmatic fallacy • Quote mining • Argumentum ad sarcina inserta • Science doesn't know everything • Slothful induction • Spotlight fallacy • Style over substance • Toupee fallacy • Genuine but insignificant cause • Argument from incredulity • Appeal to age • Argumentum ad nauseam • Phantom distinction • Appeal to common sense • Argumentum ad hysteria • Omnipotence paradox • Argument from etymology • Appeal to trauma • Countless counterfeits fallacy •
| Ad hoc: |  No True Scotsman • Moving the goalposts • Escape hatch • Handwave • Special pleading • Slothful induction • Nirvana fallacy • God of the gaps • PIDOOMA • Ad hoc • Tone argument •
| Arguments from ignorance: |  Science doesn't know everything • Argument from incredulity • Argument from silence • Toupee fallacy • Appeal to censorship • Science was wrong before • Holmesian fallacy • Argument from omniscience • Willful ignorance •
| Causation fallacies: |  Post hoc, ergo propter hoc • Correlation does not imply causation • Wrong direction • Counterfactual fallacy • Regression fallacy • Gambler's fallacy • Denying the antecedent • Genuine but insignificant cause •
| Circular reasoning: |  Infinite regress • Argument by assertion • Argumentum ad dictionarium • Appeal to faith • Circular reasoning • Self-refuting idea •
| Emotional appeals: |  Appeal to fear • Appeal to emotion • Appeal to confidence • Deepity • Argumentum ad baculum • Appeal to shame • Appeal to flattery • Tone argument • Appeal to money • Argumentum ad fastidium • Appeal to gravity • Appeal to consequences • Loaded language • Style over substance • Appeal to pity • Appeal to hate • Pathos gambit • Shaming • Degenerate • Abomination •
| Fallacies of ambiguity: |  Fallacy of accent • Equivocation • Fallacy of amphiboly • Quote mining • Fallacy of ambiguity • Moral equivalence • Scope fallacy • Suppressed correlative • Not as bad as • Etymology • Continuum fallacy • Wronger than wrong • Definitional fallacies • Code word • Phantom distinction •
Formal fallacies: |  Confusion of the inverse • Denying the antecedent • Non sequitur • Affirmative conclusion from a negative premise • Not even wrong • Chewbacca Defense • Affirming a disjunct • Illicit process • Four-term fallacy • Negative conclusion from affirmative premises • Fallacy fallacy • Substituting explanation for premise • Enthymeme • Syllogism • Formal fallacy • Existential assumption • Masked man fallacy • Self-refuting idea • Argument by gibberish • One single proof • Affirming the consequent • False dilemma • Conjunction fallacy •
Fallacious arguments: |  Bumblebee argument • Fatwa envy • Gotcha argument • Hoyle's fallacy • Intuition pump • Logic and Creation • Not Circular Reasoning • Peanut butter argument • Great Beethoven fallacy • Fallacy of unique founding conditions • Evil is the absence of God • Argument from first cause • How do you know? Were you there? • Argument from design • Argument from beauty • Appeal to nature • Solferino fallacy • Religious scientists • Nothing to hide • Argument from fine tuning • Creep shaming • "I used to be an atheist" • Atheism as a religion • Argumentum ad populum • Argument from morality • Anti-environmentalism • Appeal to bias • Apophasis • Argumentum ad nauseam • Appeal to censorship • Argumentum ad sarcina inserta • Blaming the victim • Bait-and-switch • Danth's Law • Chewbacca Defense • Canard • DARVO • Demonization • Escape hatch • Friend argument • Everyone is racist • Gish Gallop • Greece-baiting • Gore's Law • Ham Hightail • Just asking questions • Leading question • Loaded language • Linking to authority • Loaded question • Lying by omission • Motte and bailey • Nazi analogies • Moving the goalposts • One single proof • Pink-baiting • One-way hash argument • Pathos gambit • Quote mining • Poisoning the well • Quidquid latine dictum sit, altum videtur • Race card • Red-baiting • Red herring • Release the data • Science was wrong before • Shill gambit • Straw man • Silent Majority • Uncertainty tactic • Style over substance • Terrorism-baiting • Weasel word • What's the harm (logical fallacy) • Whataboutism • Bullshit • Logical fallacy • Banana argument • Scapegoat • How come there are still monkeys? • Anti-racist is a code word for anti-white • Ontological argument • Omnipotence paradox • Presuppositionalism • Just a joke • Countless counterfeits fallacy •
Conditional fallacies: |  Slippery slope • What's the harm (logical fallacy) • Special pleading • Conditional fallacy • On the spot fallacy • Appeal to the minority • Argumentum ad populum • Galileo gambit • Professor of nothing •
| Genetic fallacies: |  Genetic fallacy •
|  | Appeals to authority: |  Ipse dixit • Appeal to confidence • Argumentum ad populum • Argument from authority • Linking to authority • Silent Majority • Invincible authority • Appeal to celebrity • Ultracrepidarianism • Appeal to the minority • Galileo gambit • Appeal to identity • Weasel word • Professor of nothing • Euthyphro dilemma • Divine command theory •
|  | Ad hominem: |  Ad iram • Argumentum ad cellarium • Bulverism • Poisoning the well • Blaming the victim • Tu quoque • Whataboutism • Nutpicking • Jonanism • Demonization • Shill gambit • Appeal to bias • Fallacy of opposition • Association fallacy • Damning with faint praise • Pathos gambit • Appeal to identity • Argumentum ad hominem • Nazi analogies • Not an argument • Nothing to hide • Scapegoat • 地下室论证 •
| Imprecision fallacies: |  Apex fallacy • Overprecision • Cherry picking • Overgeneralization • Texas sharpshooter fallacy • False analogy • Appeal to fiction • Spotlight fallacy • Pragmatic fallacy • Selection bias • Anecdotal evidence • Category mistake • Nutpicking • Imprecision fallacy • Confounding factor • Fallacy of accident • Neyman's bias •
Valid logical methods: |  Rapoport's Rules • Negative evidence • Reductio ad absurdum •
Fallacy collections: |  SeekFind • Nizkor Project • Fallacy Files • Your Logical Fallacy Is • Logically Fallacious •