What Sherlock Holmes Got Wrong | Deduction, Induction, and Abduction
ฝัง
- เผยแพร่เมื่อ 8 ก.ค. 2024
- Sherlock Holmes is famous for his deductions. But what if they're not deductions at all?
00:00 Introduction
00:24 Deduction
00:57 Do deductions move from the general to the particular?
01:39 The key characteristic of deductions
02:21 Induction
02:45 Do inductions move from the particular to the general?
03:21 The key characteristic of inductions
04:26 A special kind of induction
05:35 Semantics?
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Reference:
The best discussion of the distinction between the three kinds of reasoning I outlined here comes from "How We Reason" by Philip Johnson-Laird - cognitive scientist extraordinaire. Chapter 13 is on Sherlock and abductions. It's his model that I'm describing.
The clips are from the BBC series "Sherlock," starring Benedict Cumberbatch. Used here for educational purposes.
Your video reminded me of a statement on cognitive capabilities in the Sherlock Holmes novel "A Study in Scarlet". Holmes states that a brain's memory space is limited and he thus only remembers about stuff which he considers important for his detective work (and forgets everything else). I've pondered about the statement quite some time since it deviates from my personal experiences, and would be interested what you as an expert in this field say on it.
The original text is: "I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones."
Not an expert, but the problem with this type of thinking of only remembering stuff that is immediately useful is that unlike the fictional world, real life is very unpredictable, what may seem like useless information could be useful in the future, you only understand that in hindsight.
Steve Jobs explains this in his famous Stanford Commencement Speech, he drops out of college, but still takes a class in calligraphy, this class was interesting but useless to him at the time, this very knowledge of calligraphy 10 years down the line helped in the design of the Macintosh, he could not have even imagined even in his wildest dreams how that knowledge would have helped him then, you cannot connect the dots forwards, you can only connect them backwards.
2:21 This is actually MIND BLOWING in galactical proportions cause it makes so much sense!!!! Especially in the modern "tamed" world. Cause if you never saw any variation of something you will logically and intuitively believe, many times without consciously thinking, that you have figured it out and never will see something different. There's also our IRRITATING notion of separating things in "normal" and "not normal" even though it's totally arbitraty, it's what makes uncanny pictures go viral from time to time (momo was her name?) and horror genre exist. The swan analogy is really a wake up call, i like Dr. Stone approach to magic/superpowers, "it's not magic cause we dont understand and challenge our assumptions of the world!!! It's just how it is or always were and we're just learning now! We're touching a totally unknown field of science, isnt exhilirating?!" Magic is still science, we just discovered we were too overconfident.
That's why LOOOOVE lies, detectives, magic, conman and gambling cause that's what's human life is, we're experts at making idiots of ourselves and i think guys who make fooling people and exposing this for are living are better searchers of truth than scientists (extreme, i know, but there's something with things like death note that i dont see anywhere, and i think the use of machines and other disciplines is what give science an edge, as well more people doing and/cause it's more socially acceptable).
Aduction? Thank you. Student nurse, makes me think of diagnosis where it would be helpful to learn about the process of aduction which would provide an explanation for a symptom rather than just a deduced statement about the condition. E.g. the patient is limping therefore he must have something wrong with his leg is a deduction but moving forward with that an aduction would be explaining why there is something wrong with the patient's leg bringing the nurse practitioner closer to a useful cause and eventually diagnosis.
Great example! It helped me. But i think Falsification and scientific method are better instead of outdated philosophical approach (dr stone really hits home on how unintuitive reality can be). Read Superforecasters, it's basically a college course on scientific reasoning and being a more responsible thinker, most elucidating book i ever read. I went to predict better and got out a better human.
I have an exam next month in scientific theory. And this was useful. Thank you 👌🏼🧐☺️
The best story who avoids the phone scene is Akagi, especially though the perspective of washizu, akagi toys with his tendency for comfirmation so much that even when he tries to disconfirm he's toyed, apply calling akagi as the Devil after a point. "INSANE!!!! This is insane!!!! Even if i try to think or not to think i ended up ALWAYS giving what he wants!!! Why i always do that?!"
Thank you for this video! I’ve been watching BBC Sherlock and every time they say “deduction” I want to rip my hair out lol
The only way to approach the deduction is by applying all the rules of inference, and replacement. Deduction also produces 2 kinds of arguments that is valid and ivalid if the deduction produces the argument with the conclusion follow the premises ,the argument is valid if and only if the conclusion must be true if isn't true then the argument is invalid.Note that if argument is valid doesn't mean it sound but the invalid argument always unsound even if you apply modus ponen correctly that is
If P1 then P2
P1
Therefore P2
Doesn't guarantee you will ended up in sound and valid argumen here's an example:
(1) All wines are soft drink (Premise)
(2)Ginger ale is a wine(Premise)
(3)Therefore,Ginger ale are soft drink (1,2 modus ponen)
Is this argument valid and sound?the answer it's valid and unsound since it has false premise eventhough the conclusion is true but if we change the premises however:
(1)All wines are beverage(Premises)
(2)Chardonnay is a wine (Premises)
(3)Therefore, Cahrdonnay is a beverage (1,2 Modus Ponen)
This is a valid and sound argument by modus ponen yet the 'Deduction' that Holmes use even doesn't touch the most basic rules of inference nor single any of rules of inference and replacement,if the argument that use the rules of inference still have a big chance to have false premises and unsound what would you expect from the argument that doesn't use single of them?
Could you make also a video about how with your experience as a learning scientist
would prepare for a school, college or university exam?
Yes - for sure. Something should come out in July. Thanks for the idea!
@@benjaminkeep Hi Dr Ben, I would like to know what is the track on the swan part, sounds really familiar to me. Is it QI?
Thanks
What do you think about doing some materials on Go game?
Not likely, I'm afraid. I played go pretty seriously in high school, college, and a little in grad school, but the most I do now is introduce young kids to the game. There's probably some good vids on TH-cam, if you look (try adding "weiqi" or "baduk" to the search because "go" by itself is hard to search for). Sensei's Library is a great (older) resource, too.
If I ever have time again, I would love to get back into the game.
1:07 Funnily enough, this is also done by superforecasters, Tetlock stresses that they start with the broad statistics and then look at the particular details, people do the other way around, i mean, it isnt more logical???? Who cares if the difference in number from farmers to librarians is 9/1 THIS GUY SCREAMS LIBRARIAN!!!! And yet they dont, or are informed to, not think that way. I guess if you can/have time, it doesnt hurt to reason this way 1st and then go with your "intuition" if it still feels more accurate.
Lol once you see it, you can't unsee it. I guess most problem solving shows follow the same pattern, then. Pass off abduction as deduction .
Ok I've got a biased deduction and you will tell me where I got it wrong 👍🏻
1- what is rare is expensive
2- a cheap horse is rare
3- thus, a cheap horse is expensive !!
Doesn't make sense 😜
The two premises contradict each other. To see why, it's helpful to use the word "all" in the first premise. All rare things are expensive. So there can't be a cheap rare horse, because something cannot be both cheap and expensive at the same time. : )
There are many cases of false math "proofs" where the premises contradict each other, although it's considerably less obvious as to why.
But if you look at it from an relative different point of view to actually find a horse that is cheap is rare. So a cheap horse is rare. And if all rare things are expensive, we could still arise to a cheap horse is expensive? Life is full of twisted mysteries 🤨
@@jerryasagba7352 If you take cheap horses really being rare into consideration you should also consider that not all rare things are expensive. If I write down 100 numbers on a note, that note is going to be entirely unique as the chances of another similar note existing are almost zero, but that rarity doesn’t mean a whole lot of people are going to pay anything for it.
@@mr.winter538 damn thats also a sick perspective. Good one
Is deduction basically axiom based reasoning? I don’t understand why they needed to invent a new term for this when math has been doing this forever.
Is axiom based reasoning basically deduction? I don’t understand why mathematics needed to invent a new term for this when everyone else has been using this forever
No it isn't, you can make a deduction based on axiomatic reasoning but not all axiomatic reasoning are deductions. You can make a deduction that 2 + 1 = 3 based on how the real number, 2, +, 1, = and 3 work, and now you know that it hold true. Thing tho get more complicated with more advanced stuff for example: sum of x from 1 to n = n(n+1)/2,
I can show by deduction that it holds true in a special case like if x = 1 then n(n+1)/2 = 1*2/2=1 (you can try for higher numbers if you want to) but then to show that it is true for all n is another thing, where deduction is just not strong enougth to show that, so instead we use what is called an induction method, we know that the sum of x from 1 to n +1 minus sum of x from 1 to n is equal to n + 1 and by using that fact we are going to check if (n+1)(n+1+1)/2 - n(n+1)/2 is actually equal to that aswell, so with some algebra we get (n^2+3n+2)/2 - (n^2+n)/2 = (2n+2)/2 = n+1 and thus we have shown that sum of x from 1 to n = n(n+1)/2 is actually true, and this is all based on the axioms of the set of real numbers, but is in fact an induction and not a deduction.
do you still hold your posture expressed on this video to this day?
Do you mean my physical posture? Have an old injury that I've been rehabbing for years and it's a consequence of that.