Editing Talk:3210: Eliminating the Impossible

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I’ve found that when looking for an item, I’ll search harder and more thoroughly in the places where the item is supposed to be, which is just frustrating and usually unsuccessful.
Then I realized that if the item isn’t where it’s supposed to be, then it’s somewhere ''it isn’t supposed to be'' - so I start looking in those places.
[[Special:Contributions/170.64.111.76|170.64.111.76]] 20:51, 20 February 2026 (UTC)

It also assumes exclusion of the middle.
[[User:MithicSpirit|MithicSpirit]] ([[User talk:MithicSpirit|talk]]) 20:59, 20 February 2026 (UTC)
:I think you're kind of right, but it's a weird situation. Disjunction elimination does not require LEM. I can imagine that we have established some list of ''n'' "possibilities" ''p''<sub>0</sub>, ''p''<sub>1</sub>, ..., ''p''<sub>''n''</sub>. What does it mean that these are the only possibilities? Naturally, it means ''p''<sub>0</sub> ∨ ''p''<sub>1</sub> ∨ · · · ∨ ''p''<sub>''n''</sub>. Now, if we eliminate all but the ''k''<sup>th</sup> possibility, that means we have ¬''p''<sub>0</sub>, ¬''p''<sub>1</sub>, ..., ¬''p''<sub>''k''-1</sub>, ¬''p''<sub>''k''+1</sub>, ..., ¬''p''<sub>''n''</sub>. By repeated use of disjunction elimination, this proves ''p''<sub>''k''</sub> intuitionistically, so the ''k''<sup>th</sup> possibility ("whatever remains") is provable ("must be the truth"). The problem with this approach is proving the original disjunction. How did we show to begin with that one of those ''n'' possibilities must hold? To do that intuitionistically requires actually proving one of those statements to begin with. And since only one of them is true, we must have already proved ''p''<sub>''k''</sub>, rendering this argument pointless. Still, it technically is valid. [[User:EebstertheGreat|EebstertheGreat]] ([[User talk:EebstertheGreat|talk]]) 14:20, 21 February 2026 (UTC)
::I originally interpreted it as taking the collection of all (relevant?) propositions, excising the false ones, and deducing that anything that was not excised must be true. Effectively meaning that that if ¬p does not hold then p must hold, which is EM. I think your interpretation is incorrect because the comic does not require the collection of "whatever remains" to be nonempty, so we don't necessarily have the disjunction. [[User:MithicSpirit|MithicSpirit]] ([[User talk:MithicSpirit|talk]]) 20:43, 21 February 2026 (UTC)

These guys sure are some professors of logic (I'm not sure if they own any doghouses, is what I mean). [[User:Fephisto|Fephisto]] ([[User talk:Fephisto|talk]]) 21:07, 20 February 2026 (UTC)

As and when the Explanation gets written (I imagine that someone's right in the middle of that now), it must be noted that Sherlock Holmes's self-proclaimed "Deductive reasoning" is really {{w|Abductive reasoning}}. (I actually blame Sir Arthur, rather than Sherlock (or 'narrator' Watson), for that error... But then he also believed in fairies, so obviously he's less than perfectly rational.) [[Special:Contributions/81.179.199.253|81.179.199.253]] 21:17, 20 February 2026 (UTC)
:Well, nobody did do anything with it, in the last hour or so, so I scrawled something pretty basic for others to ruthlessly dismember and 'remember' in their own prefered fashion. [[Special:Contributions/81.179.199.253|81.179.199.253]] 22:27, 20 February 2026 (UTC)

I think its pretty nice how this comics number is a countdown from 3. [[User:Xkdvd|Xkdvd]] ([[User talk:Xkdvd|talk]]) 22:57, 20 February 2026 (UTC)

By the way, meant to say earlier... just today (well, the day just before the midnight just gone), I spent a few moments trying to help someone find a single glove. They'd looked various places, and I ''went out to look in the car'' (twice, actually, because first I just checked the 'normal' places, footwells, door-pockets... then realised I hadn't actually checked the glove-compartment itself (which I don't think I've ever used to store gloves, of course, but I'd have looked silly if I hadn't gone back and checked it once it had occured to me) so out I went again) in order to ''not'' find the glove. Cue, later, the revelation that it had been in a bag (in the house) all along. And this was all mere hours ''before'' Randall published this comic. So, as we all used to say on the now defunct Fora, "<abbr title="Get Out Of My Head, Randall">GOOMHR</abbr>!" [[Special:Contributions/81.179.199.253|81.179.199.253]] 00:24, 21 February 2026 (UTC)

It's also possible to miss an item in a space you've searched. For instance, as a 12- or 13-year-old I once concluded that something (I forget what it was) must not be in my room, because I'd partitioned the rectangular box defined by the walls, floor and ceiling and searched each of the partitions. It turned out to be outside that box but still inside my room, because it was on the windowsill. [[User:Promethean|Promethean]] ([[User talk:Promethean|talk]]) 00:39, 21 February 2026 (UTC)

I actually did find it in the car though.--[[Special:Contributions/2604:3D09:84:4000:6FFB:F472:7679:FF75|2604:3D09:84:4000:6FFB:F472:7679:FF75]] 02:34, 21 February 2026 (UTC)

Reminds me of this from Math Hysteria by Ian Stewart: 'As I have often stated, when you have eliminated the impossible, then whatever remains, however improbable ... remains improbable,' said Holmes, deflated. 'There's probably something altogether different going on, and you've missed it. But don't quote me on that,' he warned. [[User:Arcorann|Arcorann]] ([[User talk:Arcorann|talk]]) 09:23, 21 February 2026 (UTC)
:I was going to get that actual book, before Christmas (after I'd decided what other book I was getting for someone else, when visiting a good bookshop with a nice selection of not-necessarily-new publications), as there's still just about space for it on my 'Pratchett-adjacent' bookshelves next to his (and specifically Jack Cohen's) other stuff. Which I'm a bit sorry now that I never got signed by them (both, where relevent) while I still could, the few times we had all crossed paths. [[Special:Contributions/81.179.199.253|81.179.199.253]] 14:25, 21 February 2026 (UTC)

If it's not in the car, it's in the cdr. --[[Special:Contributions/2A02:3100:25A0:9400:6CEB:97FF:FE5B:8BDC|2A02:3100:25A0:9400:6CEB:97FF:FE5B:8BDC]] 11:06, 21 February 2026 (UTC)
: Yeth. {{unsigned ip|174.130.97.11|14:10, 21 February 2026}}

To be fair, it is SHERLOCK HOLMES making the comment. He literally means when you have actually eliminated all other possibilities. And he was pedantic enough to be thorough about it. [[User:Dúthomhas|Dúthomhas]] ([[User talk:Dúthomhas|talk]]) 21:27, 21 February 2026 (UTC)
: Not at all; upon re-reading The Sign of the Four (his first use of the phrase) he most certainly has not eliminated all other possibilities in both his uses of the phrase. Hilariously, he then comments "I never guess" [[User:Nerd1729|Nerd1729]] ([[User talk:Nerd1729|talk]]) 22:01, 21 February 2026 (UTC)
:: I am unsure how you make that claim. Holmes is quite pedantic in explaining the peculiarities of how he arrived at both deductions, and he is a stickler for details and minutiae of his environment — the guy studies tobacco remains to the point that he can tell you who’s buying it when he finds it someplace uncouth. Unless you suggest that Holmes should suppose Watson — a man bound by habit and practicalities — should act out of character and wander through the _peculiar reddish_ earth just to mess with Holmes, or in the second instance that we have knowledge of some _other_ method of entering that room that Doyle did not? ’Cause I don’t think that _abnormal_ behavior or circumstances qualifies as the normal possibilities being eliminated before considering the _improbable_. I will agree that Holmes was pretty full of himself, tho. [[User:Dúthomhas|Dúthomhas]] ([[User talk:Dúthomhas|talk]]) 1:24, 22 February 2026 (UTC)
::: Holmes deduces that Watson had sent a telegraph because he had not seen Watson write a letter that morning and Watson had an adequate collection of stamps and postcards. What about the possibility then that Watson had written a letter the previous day, only to send in the morning? [[User:Nerd1729|Nerd1729]] ([[User talk:Nerd1729|talk]]) 02:59, 22 February 2026 (UTC)
::::One must also assume that someone would tread in that earth ''only'' upon entering the post office, as opposed to while passing by it, and that nobody kicked or dropped any of that earth elsewhere. That the stamps and postcards on view in the desk weren't purchased on that very trip. That Watson couldn't have bought stamps or postcards, e.g. in the mistaken belief that he'd run out. That there was no other possible reason to enter the post office, e.g. to make some inquiry. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 04:33, 22 February 2026 (UTC)
:::::Yes, one assumes those things. You are applying modern-day logic to a different time and place, to people who knew the intimate details of each other’s lives in ways that we have long forgotten — Watson had no other place or time to write letters, whether that morning or some previous day Holmes would have plainly seen — as he points out to Watson (and to us) when making reference to the state of his desk. Watson would not be in the mistaken belief that he had run out of writing supplies — that is again a modern logic inapplicable to that time and, especially _to Watson_, whom I have already noted was not careless in his habits. And even today, when was the last time you went to the PO just to ask a question? You claim extraordinary possibilities are failures in Holmes’s logic about a creature of military routine. [[User:Dúthomhas|Dúthomhas]] ([[User talk:Dúthomhas|talk]]) 12:09, 22 February 2026
::::::I last went to a PO to make an inquiry a few months ago, when I wanted to know what the cost would be to ship a certain parcel to a certain destination. Then I brought it home without sending it, because I needed to clear up a few details before I did. Anyone can be mistaken about what they have on hand. "My constitution has not got over the Afghan campaign yet." When you object to "modern-day logic"... well, yes that's the whole point of this strip: the "logic" that Holmes applied doesn't stand up to scrutiny. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 15:16, 22 February 2026 (UTC)

This comic exactly hits the spot: A guy who gets high on cocaine (at least before the Reichenbach falls incident) and hasn't slept for days comes to a crime scene, tells that within a second he has ruled out all possibilities except that somebody has trained a snake (which might have infravision, but definitely is deaf) to be controlled by music in a way that it doesn't only attack without being in danger, but also wastes all of its precious venom on a human being it will not be able to swallow. The books are great but - do we really want to believe the reasoning of such a guy? --[[User:Gunterkoenigsmann|Gunterkoenigsmann]] ([[User talk:Gunterkoenigsmann|talk]]) 11:11, 22 February 2026 (UTC)
:Unless you mean a particular individual (or perhaps species of) snake with an actual deafness, they ''can'' hear. It's jawbone-based hearing (not ears), but it picks up ground vibrations as well as lower-frequency air-transmitted sounds (they can respond to human voices, with wild snakes in inhabited areas often using them as a cue to either get out of the way of any humans or making sure they're securely hidden where they are).
:Though traditional snake-charming is overwhelmingly exploiting entirely untamed snakes' response to the ''movement'' of the charmer and his instrument (the 'dancing' snake being its response to the carefully-just-out-of-range 'threat' exhibited by the charmer), no doubt it can learn to expect to be roused by lower-frequency vibrations coming from the 'pungi' that is being played.
:(The higher tones and any melody would be more just for the human audience, of course, and doesn't do much to 'charm' the snake, which may also have been fairly 'fresh caught' from the wild with nothing ''but'' instinct behind its own part of the performance; it's mostly an act by the charmer, similar to how a bull-fighter isn't expected to have changed a bull's behaviour but instead himself learn to react to a bull's natural aggressiveness. ...As it might have been said by Bluebottle in The Goon Show, if the bull charges to the left, he moves towards the matador; if it charges to the right, he moves towards the picador; and if it charges straight at him..? ...he runs to the back-a-door!)
:Ophiologists (or indeed herpetologists in general) might be able say how well snakes can be ''well trained'' to a given cue (and perform non-instinctive actions such as being sent through a grating, envenomate non-threat/non-food targets and then return), and the higher pitch instrument (a tin-whistle, if I recall the story involved) wouldn't seem to me to be suitable communicating device, but I've no doubt that it's at least partly practical, just not (trivially) possible to the full extent as asked for by the story's plot. [[Special:Contributions/82.132.238.165|82.132.238.165]] 16:54, 22 February 2026 (UTC)