History Main / ConvictionbyCounterfactualClue

* One ''ComicBook/SupermansPalJimmyOlsen'' comic featured Jimmy [[WholesomeCrossdresser crossdressing]] to [[ItMakesJustAsMuchSenseInContext test the detective skills of his fanclub]]. They found him out in part because "Jackie" had tied a bowtie into a garter, to show "herself" as a member of the club, and according to them, "girls don't wear neckties and never have the practice to tie them ''that'' well." This is probably news to the millions of women who help their boyfriends, sons, or husbands with getting their ties on, not to mention those teenage girls that have to wear ties as part of a [[CatholicSchoolGirlsRule school uniform]].

* One ''ComicBook/SupermansPalJimmyOlsen'' comic featured Jimmy [[WholesomeCrossdresser crossdressing]] to [[ItMakesJustAsMuchSenseInContext test the detective skills of his fanclub]]. They found him out in part because "Jackie" had tied a bowtie into a garter, to show "herself" as a member of the club, and according to them, "girls don't wear neckties and never have the practice to tie them ''that'' well." This is probably news to the millions of women who help their boyfriends, sons, or husbands with getting their ties on.

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[[quoteright:350:[[ComicBook/SupermansPalJimmyOlsen https://static.tvtropes.org/pmwiki/pub/images/bowtie_3.jpg]]]]
[[caption-width-right:350:Never mind that the girl standing directly behind him now knows the barber's name.]]

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* The British "Adult" comic ''ComicBook/{{Viz}}'' ran parodies of this, among others the "Spot The Clue" strip. A whodunnit situation is shown, with the reader being asked to work out who the perpetrator is. Each time the villain is the one who made an innocuous error, ranging from incorrectly describing the era of a piece of furniture, [[TakeThat to claiming to have been sending emails on a piece of hardware that everyone knows is too unreliable to work.]]
* Lampshaded by "Inspector Bougret", an occasional feature of Gotlib's strip ''Rubrique-à-Brac''. Presented with two suspects, one of whom is blatantly guilty, Bougret accuses him for an absurd reason. In one case, the murder weapon is a brick of a material unknown on Earth; Bougret accuses the one who willingly shakes his hand, because only an extraterrestrial would shake a cop's hand -- not because he's visibly not human.
* One ''ComicBook/SupermansPalJimmyOlsen'' comic featured Jimmy [[WholesomeCrossdresser crossdressing]] to [[ItMakesJustAsMuchSenseInContext test the detective skills of his fanclub]]. They found him out in part because "Jackie" had tied a bowtie into a garter, to show "herself" as a member of the club, and according to them, "girls don't wear neckties and never have the practice to tie them ''that'' well." This is probably news to the millions of women who help their boyfriends, sons, or husbands with getting their ties on.
* An issue of ''ComicBook/PowerGirl'' featured an exploration of this, when [[Franchise/{{Batman}} Bruce Wayne]] gives the corpse of a supposed suicide victim an autopsy. He points out that the bullet wound is on the forehead, at which Dick Grayson points out that it's not unheard of in suicides. He then points out that the exit wound suggests the bullet came from straight-on, and Dick again points out that it's weird, but not impossible. Then he points out that the angle suggests the gun was being held in the victim's left hand when they were right-handed, and Dick points out that the victim was a BadassNormal and reasonably able with his left hand. Bruce responds by pointing out that, yes, it's ''possible'' that the victim held the gun to his head at a bizarre angle with the wrong hand, but it's not ''likely'', and Dick keeps focusing on the least likely possibility - which is what causes them to conclude that they're being influenced mentally. And just to nail the coffin, he gives a much less disputable bit of evidence; namely, the bullet hole is [[PrettyLittleHeadshots too neat]] for a gun-to-the-head shot.
* In "Ego Trip", Creator/JohnByrne's story in ''[[Franchise/{{Batman}} Batman]] 3D'', a receipt is found that mentions delivery of "zzxjoanw" to the victim. The cops figure it must have been some garbled message to someone named "Joan". Batman, armed with encyclopedic knowledge, knows that a zzxjoanw is actually a Maori drum and deduces that the victim was a collector of obscure musical instruments. The problem is that in real life, "zzxjoanw" is actually a fictitious entry in a 1903 music encyclopedia that managed to make it into two other books of "interesting words" over the next 50+ years, and no such instrument actually exists (Maori doesn't even have the letters Z, X, and J).
* Happens InUniverse in a ComicBook/DisneyDucksComicUniverse story. Hewey, Dewey and Louie see a celebrity order carrots in a restaurant, and -- since said celebrity hates carrots, as stated on every magazine -- they deduce that he must be an impostor, and the original has been kidnapped. The story ends with them freeing the real celebrity, who invites them to dinner as a thank-you... and orders a dish of carrots. When Hewey, Dewey and Louie express their incredulity, he answers "Why, do you really believe everything magazines print out?"

* [[http://lileks.com/bleats/archive/23/0123/35.html In one]] ComicStrip/LanceLawson strip, a clerk at an office says he was held up up by two armed gunmen. One tied up the clerk, while "Mac" went into the payroll office to deal with the guard. When a shot rings out, the unnamed gunman complained that Mac shot the guard. Then the two robbers took the money and left. Lance decides to arrest the clerk for suspicion of murder. The solution? [[spoiler:The unnamed gunman in the story couldn't actually see who shot who from his position. Even though Unnamed could've just...''assumed''.]]

* In the movie ''Film/{{Soultaker}}'', a cop investigating a fatal car crash finds it odd that the doors of the car are both wide open. He doesn't buy that a closed, even locked car door could fly open if the car were to crash, and asks his partner, "What are the odds?" (It's because the ghosts of the passengers opened them.) In reality, the odds of both doors of a two-door car being flung open in a high speed head-on collision are ''pretty goddamn good''. This didn't escape notice when the movie was featured on ''Series/MysteryScienceTheater3000''.
* In ''Film/RearWindow'', the main character Jeff and his girlfriend Lisa suspect that a man living in an apartment near Jeff's place has murdered his wife. They ask a police detective friend of Jeff's to investigate the case, but he comes to the conclusion that the woman has simply gone on a trip. Lisa then argues that if they can find the woman's wedding ring in the apartment, that would prove that she was murdered, as no woman would go on a trip and leave her wedding ring behind. [[spoiler:Lisa eventually sneaks into the apartment and finds the ring, which is enough to convince the detective that the woman may have been murdered.]] In real life, there might be numerous reasons why someone wouldn't wear their wedding ring, especially if they're going through marital strife, which was the case with this woman.

* From ''Literature/TwoMinuteMysteries'' by Donald Sobol.
** The "mule" clue was used in "The Case of Molly's Mule". Sobol would later reuse this clue in an ''Literature/EncyclopediaBrown'' mystery called "The Case of the Gold Rush". The first time can be excused as a common mistake, but the second time less so.
** A ''Two-Minute Mystery'' had a deaf witness's testimony that he [[ReadingLips read the suspect's lips]] and took special note of it because the suspect was whispering called into question, because supposedly, he shouldn't have been able to tell the suspect was whispering. However, whispering is just when instead of using your vocal cords normally, you create turbulence with them, producing a hissing sound. This then requires you to use your lips and mouth to create sounds that your vocal cords normally would, and is ''very'' noticeable to a lip reader. You can easily demonstrate this by saying the same word as a whisper and in normal voice, and feel how different your mouth moves. Then try freezing your jaw and lips in place and speaking, something you can do mostly understandably with operating your vocal cords normally, but you can't produce meaningful sounds at all if you try it while whispering.
** In one ''Two-Minute Mysteries'' story, a man relates how he leaned over his train bunk and read a headline on the newspaper the man below him was apparently reading. His companion deduced that the man with the newspaper was the perpetrator, because the ''only'' way the first man could have read the headline is if the newspaper was held upside-down (and therefore upside-up, relatively speaking, to the first man's eyes.) However, many people can read upside-down text ''just fine'', especially if the text is in a large font and the message short (like a newspaper headline). Many dyslexics can read upside down almost as fast at reading the normal way, sometimes even faster. Even without any skill at it, everyone who can read can decipher upside-down print letter by letter. It may take a few minutes, but what's time to someone sitting bored in a train? Or, even easier, the top half of the paper may have been folded back while the man read the bottom.
** In "Murder at the Zoo", Haledjian meets with a zookeeper after a doorman working at the zoo is found killed. The zookeeper claims to have been alerted to the murder when he heard the scream of a giraffe, since one of them had been caught in the crossfire. Instantly Haledjian declares him to be the real murderer, because according to him, giraffes have no vocal cords. In reality, giraffes have vocal cords so large that they usually make sounds too low in pitch for humans to hear. This is why biologists for a long time thought that giraffes made no vocalizations. While adult giraffes usually seem silent from our perspective, [[https://www.youtube.com/watch?v=Y7iuOZVJhs0&t=1m50s calves can be quite noisy.]]
** An alleged suicide note from a linguistics professor is determined to be a fake due to some grammatical "mistakes" that a true linguist would never make, including the use of a split infinitive such as "''to'' '''''boldly''''' ''go''"). First, correctness of split infinitives is a matter of great debate; while some do abhor them, many have no problem with them at all. Second, Sobol mixes up ''linguists'' with ''grammarians''; the former being a study of aspects of a language such as what sounds are meaningfully distinct, how it expresses things that will take place in the future, and other stuff like "is there a separate word for 'hand' vs 'arm' or do they use only one word?" while the latter being the study of restraints on words and the order they go in. Finally, that's before you have to wonder if a person ''contemplating suicide'' is in the correct frame of mind to even consider proofreading.
** In one of the Two-Minute Mysteries, a man's death is taken not to be suicide because he had recently suffered a heart attack, so a salt shaker on his table would mean another person was present, since the man himself would not be adding any to his food. A man intending to take his life could easily have ignored health concerns. In addition, [[ConvictionByContradiction couldn't he have just left it on there and never used it?]]
** One story overlaps with ConvictionByContradiction - where an inspector has an upset stomach and asks for "Bicarbonate of soda" at a bakery. When they say they don't have any, he somehow deduces they're a front since that's baking soda and no bakery would be without it. On top of all the various reasons for why the baker may not have any (They're out, he doesn't know what it means since it was called "Sodium Bicarbonate" instead), the bakery is also stated to have been one for pies - pies use baking ''powder'', not baking ''soda''. While baking soda can be used to lower the pH of acidic ingredients (such as lemons and limes), it's not often used for pies and one can easily substitute it with more baking powder since Baking Powder is just baking soda with cream of tartar.
** One of the Inspector Berkovich stories[[note]]a collection of short stories for Israeli Russian speakers, with many of the stories being expansions of the Two-Minute Mysteries[[/note]] has a witness claim he saw a man being murdered while a clock was ticking -- except it was digital. The twist is; the man was completely honest; he was hearing a particular radio station which always transmitted a metronome's ticking for a few minutes before its regular broadcasts started.
* ''Literature/EncyclopediaBrown'', the former TropeNamer, also by Sobol, often bases the solution of mysteries on assertions that a certain event could not have happened as described for a particular reason. In some cases, the reason would make the event unlikely, but not impossible. Other times, the reason is simply false.

* Literature/SherlockHolmes:
** In "The Adventure of the Blue Carbuncle", Sherlock Holmes deduces that the owner of a lost hat must be an intellectual, because it is a big hat, [[MyBrainIsBig and so he has a large head]]. This was partly ScienceMarchesOn -- [[http://en.wikipedia.org/wiki/Phrenology that was actually a serious scientific theory at the time]] -- but even in the context of the era, it ignores the possibility that the hat's owner might simply have a very thick head of ''hair'' atop an average-size head, or a simple preference for oversized hats.
** In "The Adventure of the Priory School", Holmes deduces the direction a bicycle was heading by the fact that the hind tire track passes over the front tire track. However, the hind tire would pass over the front tire tracks regardless of the direction (unless the bicycle was in the process of turning at the time). [[https://mindyourdecisions.com/blog/2010/02/02/a-mystery-sherlock-holmes-couldnt-solve-but-you-can/ This article]] explains an actual way of figuring out the bicycle's direction. Conan Doyle himself checked that theory after getting some mail from the readers, and admitted that this is, indeed, his mistake; he also said that Holmes could've used a different clue: on an uneven ground the bike leaves a deeper track when going upwards than downwards, and that is enough in the context of the story.

* One entry in ''Literature/TheArmchairDetective'' series stated that one true way of knowing if a pre-UsefulNotes/WorldWarII telegram is false is if the phrase "UsefulNotes/WorldWarI" or "The First World War" is ever mentioned, on the assumption that nobody could have foreseen a second World War before it started. However, [[http://en.wikipedia.org/wiki/World_War_One#Names it was used by some almost immediately after hostilities began.]] Note that the series in general isn't particularly prone to this. In his defense, those were not ''common'' terms, and would hardly be included in a telegram where they could easily say "The War" or "The Great War" with fewer letters. It may not be rock-solid evidence, but it's a good reason to be very skeptical. It should be noted that using them as the actual ''name'' of the War would be even more suspicious—although the First World War was, indeed, used, it at first was more of a descriptive term (IE, describing the War as the first World War in contrast to previous, non-global, wars, and, as in the case of the first recorded use of the term, the early-war term 'The European War').
* Creator/IsaacAsimov:
** "Literature/TheDyingNight": Wendall Urth, PhoneInDetective, deduces the killer's identity through the [[ScienceMarchesOn now-incorrect]] evidence that {{UsefulNotes/Mercury}} is a TidallyLockedPlanet. The killer had assumed they could safely store a light-sensitive recording in starlight and retrieve it days, or even years, later without the recording being exposed to sunlight. Current astronomical understanding is that Mercury has about three days for every two years it experiences. Asimov acknowledged this in afterwords of later printings, but said he couldn't figure out how to fix it without rewriting the entire story, so jokingly blamed it on the scientists for changing their minds.
** "{{Literature/Hostess}}": Mr Smollett, who works as a sort of "police officer" for the [[GovernmentAgencyOfFiction World Security Board]], claims that humans have adapted too much to the [[EnergyBeing non-physical]] parasite/[[MindVirus virus]] to survive, citing cancer. InUniverse, Dr Smollett realizes that his claim is bunk, because while cancer is unrestrained growth (as opposed to the decay caused by the parasite), cancer occurs even in creatures which aren't hosts to the parasite. She's a biologist while he isn't.
** "Literature/MirrorImage": [[RobotNames R (obot)]] Olivaw catches the InUniverse counterfactual when Detective Baley claims that the robot that suffered a LogicBomb when asked to admit they had been lying is proof that they had been ordered to lie, instead of being the robot that had ''not'' been ordered to lie. Baley admits that, because he isn't a robopsychologist, either one is probably just as likely. His goal wasn't to accuse the owner of the robot who broke down, but to use whichever robot broke down to accuse the older mathematician of trying to commit {{UsefulNotes/Plagiarism}}.

* One Encyclopedia Brown-esque story concluded that the suspect was obviously lying because he claimed he was at a laundromat putting clothes into a top-loading dryer. The detective claimed that ''all'' dryers are front-loading. This is incorrect; top-loading models existed on the market even in the time period when the story was written.[[note]]Although since they're pretty uncommon, it becomes a matter of going to the laundromat and checking if the place really does use top-loading dryers.[[/note]]
%% The vital clue that solves the mystery in the novel Fatal Equilibrium doesn't work at all once the FridgeLogic sets in. [[spoiler:Canoes would necessarily have a smaller price variance only if one assumes all canoes are the same, which is a bad assumption to make when applied to non-theoretical situations. This is even worse when the protagonist makes the comparison of a hammer truck and a car. Anyone with half a brain would realize that, while the price variance of a specific make and model of car would likely be smaller than that of a hammer, cars in general have a considerably larger variance due to differences in performance, fuel efficiency, mileage, current fads, etc. This effect could actually be even more pronounced in the society under question, which did not have mass production, meaning each canoe would be unique.]]
%% [[spoiler:Even in the US, a cheap canoe can be had for as little as $400, while a large Grumman can run you over $2000, ''five times'' more expensive. The price of a canoe varies with the size of the canoe, the materials it's made of, and the quality of its construction.]]
* In the battle between Archmage Gromph and [[spoiler:Dyrr the lich]] in the ''Literature/{{War of the Spider Queen}}'' series, Gromph realizes [[spoiler:Dyrr's]] shapeshift spell means [[spoiler:he's not undead anymore]], so negative energy spells can and do work on him. The kicker? He'd polymorphed into a construct, which is ''still'' immune to negative energy and [[spoiler:a Lich, unlike most undead, CAN polymorph himself as an explicit part of the runes]].
** In one of the [[Literature/ForgottenRealms Avatar Trilogy]] novels, a ghostly figure appears in front of Cyric's mercenary band and threatens them. Cyric, observing that none of the witnesses has aged as a result, concludes that the figure isn't a genuine ghost (which had an aging aura under then-current D&D rules), but a harmless product of wild magic. Not only is there no clear reason for him to assume a product of wild magic would necessarily be harmless, but there are ''several dozen'' other ghost-like creatures in the TabletopGame/ForgottenRealms Verse that it could have been, that would not age witnesses yet would be extremely dangerous in other ways. There's also some HilariousInHindsight with this situation, as later editions dropped the aging aura as a ghost ability completely.
* Creator/WoodyAllen parodied this in a story called "Match Wits with Inspector Ford", where Inspector Ford deduces that a man didn't kill himself, because there was cash in his pocket, and someone who is about to commit suicide would use a credit card.
* In ''Literature/TheMurderOnTheLinks'', the second Literature/HerculePoirot case in terms of internal chronology (''and'' of publication order), Poirot sees a stage act consisting of twin sisters (one blonde, one brunette) and deduces that one of them must be wearing a wig. [[SarcasmMode Because of course it's impossible]] that twin sisters could be fraternal, or that their parents could be a blond and a heterozygotic brunette (or two heterozygotic brunettes), or hair dye was used. While the twins are repeatedly stated to be identical in appearance, very close resemblances do happen in families, even among brothers and sisters born at separate times to the same parents.
* In ''[[Sandbox/DetectiveJoeSandilands The Palace Tiger]]'', a vital clue hinges on the murder weapon being a ''bagh nakh'' (Hindi for "Tiger's Claw"), which leaves a broken tiger claw in the wound. The weapon is described as being an actual preserved tiger paw mounted on a handle, hence the clue. In fact, the ''bagh nakh'' is a set of metal claws attached to rings which slip over the fingers; the name is metaphorical.

* ''Literature/TheDresdenFiles''
** Zigzagged in ''Literature/GhostStory''. While confronting Aristedes [[spoiler:Butters]] pretends to be a Warden. Aristedes notices that [[spoiler:Butters]] doesn't have a sword, and therefore isn't a Warden. Although said magic swords are standard Warden equipment, a situation from earlier books means they are currently unable to make new ones, so any more recently appointed Warden won't have one. Dresden notes that since neither character knows about this situation, it doesn't matter that he's technically wrong.
** In the short story "The Warrior", Harry saves a girl from being hit by a car. When her mother comes to see what happened, Harry spots a bruise on the girl and asks if he gave it to her when he pulled her out of the car's path. The girl says no, she was bruised when she fell off her bike. Harry then asks how that happened without her scraping her hands, making the mother's eyes go wide and she promptly marches the girl home. Later Harry learns that her father had been hitting her, and Harry's comment brought it to the mother's attention. Of course the girl could have easily fallen off a bike without scraping her hands. While the mother may have known or suspected what was going on, there was no real reason her to think it was particularly suspicious.

* ''VisualNovel/VirtuesLastReward'' has weird in-universe example when the clue is counterfactual to story's rules rather than real life ones. [[spoiler:When Luna asks Sigma how he knows that Dio killed the Old Lady, Sigma replies that Dio confessed to it in another timeline. When Luna calls him out on using knowledge from different timelines Sigma replies that it doesn't matter when he found the information since events that happened in the future of different timelines cannot change the past.]] Except they can and it's a major plot point.

* ''Film/LegallyBlonde'' has one of these used by protagonist law student Elle Woods to prove her client's innocence in a murder case, and [[spoiler:it also leads to a panicked confession by the real culprit]]. When Chutney, the adult daughter of the murder victim, states she was in the shower at the time of the murder happening in the same house so didn't hear gunshots, but also claims earlier the same morning she got one of her regular perms Elle points out that as someone who had been getting said hair treatment for half her life Chutney should know not to wet her hair so was unlikely to be in the shower. [[spoiler:Chutney then breaks down and confesses she actually accidentally killed her own father, she'd actually been trying to murder the accused - her stepmother.]]

* ''Manga/CaseClosed'': The Moonlight Sonata case uses the belief that [[ValuesDissonance all women are physically weaker than all men]] as a foolproof alibi. Even when there's an elderly, overweight or disabled man in the room who doesn't get the same courtesy. A female doctor is written off as a suspect because she's petite with thin arms and couldn't have lifted the bodies (each of which are taller than her and would require quite a feat to move around the way they did). Then [[spoiler:when it's found out "she" is actually a crossdressing man this alibi immediately vanishes, ''even though he's still the exact same muscleless {{Bishounen}} waif.'']]

* ''Film/LegallyBlonde'' has one of these used by protagonist law student Elle Woods to prove her client's innocence in a murder case, and [[spoiler:it also leads to a panicked confession by the real culprit]]. When Chutney, the adult daughter of the murder victim, states she was in the shower at the time of the murder happening in the same house so didn't hear gunshots, but also claims earlier the same morning she got one of her regular perms Elle points out that as someone who had been getting said hair treatment for half her life Chutney should know not to wet her hair so was unlikely to be in the shower. [[spoiler:Chutney the breaks down and confesses she actually accidentally killed her own father, she'd actually been trying to murder the accused - her stepmother.]]

** Book 7, chapter 1 ("The Case of the Electric Clock"): The culprit's alibi was that, when he walked past the victim's house, he heard the electric clock (which was unplugged when the crime was committed) ticking, the contradiction being that electric clocks don't tick. When this was first written, (back in the 1970s), this was ConvictionByContradiction, though questions like "How loud would it have to be ticking to be audible outside the house?" and "Exactly how is this an alibi anyway?" might arise. Today, we can skip straight to the fact that some electric clocks -- particularly analog clocks in which the second or third hand jumps from one mark to another and an early kind of digital clock where numbers were written on flaps that showed in succession (as shown in ''Film/GroundhogDay'' among others) -- ''do'' make sounds that, while distinct from pendulum-regulated clocks, are described as ''"ticking"''. Additionally, some digital clocks that indicate seconds will play an artificial ticking sound.

** Book 7, chapter 1 ("The Case of the Electric Clock"): The culprit's alibi was that, when he walked past the victim's house, he heard the electric clock (which was unplugged when the crime was committed) ticking, the contradiction being that electric clocks don't tick. When this was first written, (back in the 1970s), this was ConvictionByContradiction, though questions like "How loud would it have to be ticking to be audible outside the house?" and "Exactly how is this an alibi anyway?" might arise. Today, we can skip straight to the fact that some electric clocks -- particularly analog clocks in which the second hand jumps from one mark to another and an early kind of digital clock where numbers were written on flaps that showed in succession (as shown in ''Film/GroundhogDay'' among others) -- ''do'' make sounds that, while distinct from pendulum-regulated clocks, are described as ''"ticking"''. Additionally, some digital clocks that indicate seconds will play an artificial ticking sound.

** An alleged suicide note from a linguistics professor is determined to be a fake due to some grammatical "mistakes" that a true linguist would never make, including the use of a split infinitive such as "''to'' '''''boldly''''' ''go''"). First, whether correctness of split infinitives is a matter of great debate; while some do abhor them, many have no problem with them at all. Second, Sobol mixes up ''linguists'' with ''grammarians''; the former being a study of aspects of a language such as what sounds are meaningfully distinct, how it expresses things that will take place in the future, and other stuff like "is there a separate word for 'hand' vs 'arm' or do they use only one word?" while the latter being the study of restraints on words and the order they go in. Finally, that's before you have to wonder if a person ''contemplating suicide'' is in the correct frame of mind to even consider proofreading.

* Would you believe ''Series/{{CSI}}'' is accused of this?

* In ''Encyclopedia Brown'' and similar riddles there are puzzles about coins being a forgery because the name of the ruler is King Bob the First or similar. Obviously, [[Title1 no monarch referred to himself as The First]], right? Except that they did -- either to show that they're first among equals, or because they had a son named after them, or because they would indeed be the first monarch with that name, as was, for instance UsefulNotes/ThePope John Paul the First. Or recently abdicated Juan Carlos I (John Charles the First) of Spain.

* In ''Encyclopedia Brown'' and similar riddles there are puzzles about coins being a forgery because the name of the ruler is King Bob the First or similar. Obviously, no monarch referred to himself as The First, right? Except that they did -- either to show that they're first among equals, or because they had a son named after them, or because they would indeed be the first monarch with that name, as was, for instance UsefulNotes/ThePope John Paul the First. Or recently abdicated Juan Carlos I (John Charles the First) of Spain.

** In another episode, a murder suspect claims to have left his job at "5 o'clock. On the button." When the detectives question his boss, DS Matt Devlin gets suspicious when the man uses the exact same phrase. While he's correct in suspecting that the two are lying and rehearsed their stories, the thought that either man could have simply picked up the phrase from the other after years of working together never occurs to him.

** One story overlaps with ConvictionByContradiction - where an inspector has an upset stomach and asks for "Bicarbonate of soda" at a bakery. When they say they don't have any, he somehow deduces they're a front since that's baking soda and no bakery would be without it. On top of all the various reasons for why the baker may not know (They're out, he doesn't know what it means since it was called "Sodium Bicarbonate" instead), the bakery is also stated to have been one for pies - pies use baking ''powder'', not baking ''soda''.

** In one of the Two-Minute Mysteries, a man's death is taken not to be suicide because he had recently suffered a heart attack, so a salt shaker on his table would mean another person was present, since the man himself would not be adding any to his food. A man intending to take his life could easily have ignored health concerns.

[[folder:Real Life]]
* Mostly Averted in real life investigations and criminal proceedings due to detectives, judges and lawyers knowing better. However, this trope is very common in [[ConvictedByPublicOpinion the court of Public Opinion]], mostly as a result of DoubleStandard, stereotypes, bias for/against a particular group and/or ignorance.
[[/folder]]

** In "Murder at the Zoo", Haledjian meets with a zookeeper after a doorman working at the zoo is found killed. The zookeeper claims to have been alerted to the murder when he heard the scream of a giraffe, since one of them had been caught in the crossfire. Instantly Haledjian declares him to be the real murderer, because according to him, giraffes have no vocal cords. In reality, giraffes have vocal cords so large that they usually make sounds too low in pitch for humans to hear. This is why biologists for a long time thought that giraffes made no vocalizations. While adult giraffes usually seem silent from our perspective, [[https://www.youtube.com/watch?v=Y7iuOZVJhs0&t=1m50s calves can be quite noisy]].

** Book 1, chapter 5 ("The Case of the Bank Robber"): Encyclopedia Brown deduces that the blind witness is lying because he has a newspaper in his room. Ignoring all the reasons one might have a newspaper one can't read in one's room[[note]]Perhaps the hotel hands out complimentary newspapers; maybe he was using it to wrap something, or he bought something that came wrapped in the newspaper; maybe he was going to do a messy project and needed a disposable surface[[/note]], it isn't even necessarily true that blind people can't read newspapers. Most legally "blind" people still have some amount of vision, and depending on the exact nature of the vision loss, it's entirely possible to be able to read a newspaper (perhaps with magnification).

* ''Series/DoctorWho'': [[Recap/DoctorWhoS31E12ThePandoricaOpens "The Pandorica Opens"]] has an in-universe example: The [[LegionOfDoom Alliance]] believes the Doctor to be responsible for the impending reality-ending catastrophe caused by [[spoiler:the TARDIS exploding]] because "only the Doctor can [[spoiler:pilot the TARDIS]]". Not only does the audience know this is not the case, the episode makes sure to remind people that this logic is faulty by showing [[spoiler:River Song flying the TARDIS after the Doctor sends her to go get it]].

* An episode of ''Series/{{Columbo}}'' titled "An Exercise in Fatality" has a key piece of evidence that a fake suicide was really a murder hinge on how the victim's shoes were tied. This actually could have been reasonable evidence, except that the way the evidence is framed and explained is completely self-contradictory and counter-factual. The problems with Columbo's explanation are as follows:

For example, a guy's alibi is that he was caring for his pregnant mule, and he is immediately revealed to be lying, since mules can't get pregnant. We've got him! To the jail! Not so fast: there are a handful of real life cases[[note]]"handful" as in about 50-60 cases in the past 500 years, or about once every ''decade''.[[/note]] where a female mule ''has'' given birth. Thus, there's a problem with this "revelation": it's simply ''wrong''.

** Book 1, chapter 3 ("The Case of the Civil War Sword"): Bugs Meany claims to have a sword from UsefulNotes/TheAmericanCivilWar, and says it's authentic due to the engraving showing that it was given to Stonewall Jackson by Robert E. Lee after the First Battle of Bull Run. The "correct" answer was that the sword was fake, because [[AnachronisticClue nobody would have called it FIRST Bull Run]] until there had been a Second Bull Run. Given how long it can take to commission, make, retrieve, and engrave a sword, it's entirely possible that the second battle a year later already happened by the time the sword was actually finished--though the inscription is dated 12 August 1861, just a month after First Bull Run. [[ArtisticLicenseHistory There's two much bigger holes in the story that would have made better clues:]]
### First, General Lee wasn't ''present'' for the First Battle of Bull Run in the first place: the Confederates there were led by P.G.T. Beauregard. Sobol edited the epilogue in later editions to include this fact.
### Furthermore, the Confederate forces did not refer to either battle as Bull Run at all, but rather as the Battles of Manassas. The novel used the Union's preferred nomenclature, which refers to a creek that passes through the battlefield, but the Confederates usually referred to battles by the name of the nearest settlement, in this case the town of Manassas, Virginia.

** Book 5, case 3 ("The Case of the Wagon Master"): The solution relies on a frontier fort in ''1872'' following the Flag Code of ''1923''.

** Book 15, chapter 6 ("The Case of the Crowing Rooster"): The solution is based entirely on the supposed 'fact' that roosters ''only crow when they saw light'', apparently based on the urban legend that roosters crow at sunrise. The crime was a con man trying to convince kids he found a way to make roosters crow on command, but actually uncovering the cage so they saw light and thought it was sunrise; he claimed that he would soon improve the device to make hens cluck on command, and that whenever hens clucked, they laid an egg. Anybody who has been around a rooster for an extended period of time will know full well that they crow whenever the heck they want, whether the sun is out or not. And, of course, the hen part of his story should have been clearly false, especially since he was targeting the con towards chicken farmers.
** Bugs Meany lied by copying another kid's true version of events, changing washer to dryer but otherwise using the exact same words. The first kid said he'd put the clothes in from the top, and Bugs copied that detail. The counterfactual detail was the claim all dryers are front-loading; top-loading models existed on the market even in the time period when Sobol was writing.[[note]]Although since they're pretty uncommon, it becomes a matter of going to the laundromat and checking if the place really does use top-loading dryers.[[/note]]

** Book 5, case 3 ("The Case of the Wagon Master"): The solution relies on a frontier fort in 1872 following the Flag Code of 1923.