David Deutsch: A new way to explain explanation

www.ted.com For tens of thousands of years our ancestors understood the world through myths, and the pace of change was glacial. The rise of scientific understanding transformed the world within a few centuries. Why? Physicist David Deutsch proposes a subtle answer.
TEDTalks is a daily video podcast of the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes. Featured speakers have included Al Gore on climate change, Philippe Starck on design, Jill Bolte Taylor on observing her own stroke, Nicholas Negroponte on One Laptop per Child, Jane Goodall on chimpanzees, Bill Gates on malaria and mosquitoes, Pattie Maes on the "Sixth Sense" wearable tech, and "Lost" producer JJ Abrams on the allure of mystery. TED stands for Technology, Entertainment, Design, and TEDTalks cover these topics as well as science, business, development and the arts. Closed captions and translated subtitles in a variety of languages are now available on TED.com, at www.ted.com/translate. Watch a highlight reel of the Top 10 TEDTalks at www.ted.com/index.php/talks/top10

[@antuntun]

This is one of the rare lectures which had a profound influence on my way of thinking. David Deutsch has an amazing capacity of spotting and presenting complex philosophical and scientific ideas. He's a true genius!

[@danielvarga_p]

I have to agree with you!

[@sedalia9356]

His brilliance and explanation also led me to regard epistemology and knowledge as the paramount philosophy. Also, unexpectedly, helped me resolve several personal professional struggles.

[@EmperorsNewWardrobe]

⁠​⁠@@sedalia9356I’m curious. How did he help you resolve several personal professional struggles? No worries if you’d rather not disclose

[@mrcrowly11]

His book the 'beginning of infinity' is must read. This talk is a great summary, but no substitute.

[@lx4302]

CES I’m reading it right now! Omg

[@george5120]

CES except that the book has nothing to do with either the beginning or infinity. Just a catchy title intended to enhance book sales.

[@HitomiAyumu]

@@george5120 But it does have to do with the beginning of infinity. Except hes not talking about the infinity of time, he talking about the infinite growth in scientific knowledge.

[@evilgeenius2]

@Dr Wannabestein He's trying to condense the ideas in his book into a short speech and he doesn't do it brilliantly. The book is an excellent but slow burner. His ideas are astonishing

[@evilgeenius2]

@Dr Wannabestein yes, they are dr

[@MsXfi]

Ah the good old days of avant garde TED, not the BS self marketing, coachy, cheap spirituality and word saladery that we get in TED nowadays.

[@denisdaly1708]

Fully agree. This is TED classic. The only one we should have. For the last 10 years I can't stand TED. I love listening to experts and insightful people.

[@lquirosr]

I come here every once in a while, always enlightening.

[@chantzukit681]

"That the truth consists of hard to vary assertions about reality is the most important fact about the physical world. It is a fact that is, itself, unseen yet impossible to vary."

[@PicturesJester]

His delivery is off the cuff, the notes are there to let him know in what part exactly of his speech he is in. Memorizing a delivery is a way to automatize your delivery, to narrow the way you think about it so that you can't deviate from how you memorize it. Instead he understands what he has to say and the notes do the job of keeping a fixed structure in the speech

[@fallingintofilm]

@Vidas Kulbis The idea that a philosophy should apply to itself, is a really crucial and rules a lot of philosophies out straight away

[@fidetrainer]

Imagine his surprise if he survives another 100 years and discovers it was Persephone all along

[@phiguy6473]

This guy has been blowing my mind ever since his interview on Closer to Truth.

[@DanielAnderssonmoppedanne]

Mine too 🤗 Read the books, follow him everywhere and support Brett Hall 👌🏻

[@chronos2650]

Same here

[@danielvarga_p]

@@chronos2650 Same.

[@malcolmmutambanengwe3453]

The search for hard-to-vary explanations is the origin of all progress. David Deutsch

[@EmperorsNewWardrobe]

Thanks, that’s a useful quote

[@stretch3172]

His book "the Fabric of Reality" is brilliant. I'm reading it now.

[@HitomiAyumu]

+Josh Hunter He has a new book, The Beginning of Infinity, that is even better.

[@eatcarpet]

"They're saying that our opinions are caused by wizards - and presumably, so are their own." Best line.

[@BANKO007]

Deutsch is easily the most consequential and insightful thinkers I have heard in decades. I listen to people with incredibly half-baked grand theories, like Yuval Harari for example, and I am saved from being taken in by applying the ideas of Deutsch.

[@testchannel7057]

I'm pretty sure, me a college student, can teach quite a few things to Yuval if I have the chance to talk to him. He is such a fake.

[@ssj-vu3lt]

@@testchannel7057 give me 1 eg where his theory is not good

[@EmperorsNewWardrobe]

How exactly did you apply David’s ideas to Harari’s?

[@user-pc5wc3yr6r]

@@EmperorsNewWardrobeharari’s theories (in my view) are somewhat regressive, seeming to imply a lot of our development has been to our personal detriment, and humanity was better off when we were merely foragers. Deutsch by comparison says the opposite: that our survival depends on relentless innovation and growth and the pursuit of knowledge. I might be misreading Harari but I think this encapsulates the main difference in their respective messages

[@PeterFallenius]

00:00 00:18 Wondering in terms of things unseen. 01:57 The world never improved, nothing new was learned. 03:49 What had changed that made the difference between stagnation and rapid open-ended discovery? 06:21 Empiricism: Knowledge comes from the senses, not mathematics 08:21 No one’s ever seen evolution, we see rocks. 09:37 Testable conjectures are common in myths. 11:17 What is a bad explanation? 12:55 What makes the difference between good explanations and bad explanations.

[@barrywilliamsmb]

David's video jarred me into the reality of how hooked I am on entertaining communication. A dearth of chuckles, zero tricks and not one metanoic moment created so much inner head noise I could hardly hear what he was saying. Regardless, I really appreciate the ideas and concepts. Thanks David & TED!

[@mateodoris6856]

Please understand something: This man is one of the most brilliant thinkers of the modern era, despite being far less well known. In his various works, he presents a wholistic way of understanding the universe as it is currently known, from a basic level of core principles and patterns that can be seen in all aspects of human existence. I highly reccoment The Fabric of Reality and the Beginning of Infinity. They can be a bit hard to comprehend but if you take the time to read them they will genuinely make you a smarter human being.

[@KrwiomoczBogurodzicy]

16:13 - “That the truth consists of hard-to-vary assertions about reality is the most important fact about the physical world. It’s a fact that is itself unseen, yet impossible to vary.” - David Deutsch, _A new way to explain explanation_ (2009 TED Talk) [16:13]

[@Shaunt1]

This is very articulate, he does a good job explaining how things are correctly explained.

[@danielgaller5151]

The clarity of a well trained critical thinker, is mostly based on a good inner Ego control. If you can learn to accept you know soo little since you can see so little with your inmediate senses, you will start to use a more disciplined and critical way of analysizing the reality around you hence training your mind to work coherently.

[@clearmenser]

I love it !!! "Progress depends on rejecting authority..."

[@papalosopher]

Absolutely brilliant ideas. His test of easy variability of explanation is what I have been looking for to balance the yin of empiricism. Empiricism is like utilitarianism: it sounds perfect and complete, yet you suspect there is something missing there.

[@EmperorsNewWardrobe]

And what would you say is the missing thing from utilitarianism (if you’re still alive after 14 years since you wrote your comment…)?

[@papalosopher]

Yep, still alive, I do not remember watching this video though. Utilitarianism, you say? I would say that once you realise how difficult it is to define happiness, you see it isn't worth much as a philosophy. @@EmperorsNewWardrobe

[@slightlygruff]

old teds had so much meaning

[@Radjehuty]

So in other words, creating theories in which every detail plays a vital and functional role in the process that's supposed to explain a phenomenon. That's pretty cool. Nice talk :D

[@bjunjo]

Search for better explanations is the key for humanity to move forward.

[@suredoloveya]

unexpectedly excellent talk. interesting concepts.

[@arthurtfm]

Please please read his book The Beginning of Infinity. It was life-changing for me.

[@serenity748]

this should have 7 billion views

[@Mority90]

He is a genius. He has said so many interresting things.

[@kcjaymes]

i guess i was just thinking on a world wide conceptual level. Thank you for your thoughts.=)

[@thequantartist]

David Deutsch's books should be a must-read.

[@wayneturner2028]

Excellent !

[@DCWilliam24]

Wonderfully insightful.

[@david0aloha]

I think that's kind of what he's saying though. He talks about how people didn't spend much time thinking about things like the stars or other interesting phenomena and people usually accepted dogmatic truths because you would be treated as an outcast or worse for not accepting them. There was great curiousity, but a great deal of resistance - just as you say.

[@deductivist]

@neoaeonian Hard-to-vary means that it would be hard to change the explanation without introducing arbitrary bits, or making it contradict the evidence.

[@AlephNeil]

@JohnHasSeriousQ : Something that always strikes me about epistemology is the way that the philosophical points one can make about it are often mirrored by technical arguments and constructions in the field of statistics. In this case, the point about 'hard to vary' making for better explanations than 'easy to vary' is analogous to Akaike's Information Criterion and the theory surrounding it.

[@udaypsaroj]

You sound interesting!

[@christopherhamilton3621]

“Goodness of fit” expressed mathematically, yes.

[@BitcoinMotorist]

I like listening to this man. Although it took a while for him to reach his point, I was captivated by what he was saying. I also like the way he makes controversial statements and doesn't mitigate them by saying things like "I personally think that. . ."

[@Deadnature]

An elegant explanation of how to test the robustness of scientific explanations. I'd be interested in how to *measure* how hard something is to vary. Is there an objective calculation one can make?

[@EmperorsNewWardrobe]

I imagine by way of counterfactual of each variable. You take the explanatory hypothesis, and word by word imagine what happens if you remove each one. Does the explanation at any point stop explaining what it purports to explain?

[@malizaar4114]

Ever since my interest in quantum computer articles by David Deutsch, I think he deserves kudos for the effort he takes to explain his principles to the ignorant...

[@sabarapitame]

QM for the win! What it's magical is that he can explain it so easy in 17 min. Only 74k views in 6 years. We humans suck

[@vaibhavgupta20]

+Sebastián Alejandro 89K in 7 years.

[@InfiniteTravelingSpirit2BE]

Not all humans suck :)

[@honestexpression6393]

127k

[@d_wigglesworth]

151k This is a problem; insufficient uptake. How can we solve this?

[@d_wigglesworth]

Deutsch would say, “by the application of the idea to achieve rapid progress.” Is that a catch 22? Rapid progress will be made when these ideas spread. But the ideas will spread when their application achieves rapid progress.

[@vortical911]

He was using the example of how our ancestors attempted to explain the season cycle (Persephone and Hades, etc) as a metaphor for how we today, including today's scientists, attempt to explain things away with untestable & easily variable theories, and why these kinds of explanations should be avoided if we are to continue to rapidly make progress as a species.

[@chrisdavey3113]

Commenting for the algorithm. The more people that hear this and understand it, the better off we will all be.

[@cmarqz1]

Brilliant!

[@tarikabaraka2251]

David Elieser Deutsch es un físico de la Universidad de Oxford, miembro de la Royal Society. Es profesor visitante en el "Department of Atomic and Laser Physics" del "Centre for Quantum Computation", en el Clarendon Laboratory, de Oxford. Fue pionero en el campo de la computación cuántica, al ser el primero en formular un algoritmo cuántico,​ y es uno de los formuladores de la teoría de los universos paralelos dentro de la mecánica cuántica.

[@vargonian]

This guy spent most of the second half of the video re-discovering Ockham's Razor. The purpose of Ockham's Razor is to cut out excessive explanation that isn't crucial to the observed phenomena. Contrary to popularization, Ockham's Razor doesn't simply state that "the simplest explanation is the correct one." Instead, it states that you should only infer as far as the evidence takes you; no further.

[@Radjehuty]

That's exactly right. I just never thought of it in terms of the most important element in scientific understanding. We're always taught that it's thing's like falsifiability which I guess is very much related to this but not the same; and empiricism. I like how he illustrated the points even if the idea was already coined by an early logician.

[@xSilverPhinxx]

Exciting times we live in.

[@ovenlovesyou]

I agree, and if you love the tying-into-itself factor, I urge you to read his first book, Fabric of Reality, it has that to the nth degree, it's pure brilliance. His books are my favorite general-audience science books along with the Origin.

[@2011littleguy]

I’m always glad to listen to on of the smartest people who ever existed.

[@SchinTeth]

Good speech, yet again

[@Spitfireseven]

Everything David is talking about are commonly held understandings and all of these ideas, we typically entertain as seperate learnings, can be found one by one right here on the net. Go to, "What the Bleep Do We Know" for a great outline of this stuff. David's actual discourse is based on how wrong we can be on what we think we know. It is amazing how flawed we really are in assembling a complete picture of the universe and all the dimensions adjacent to it.

[@aspTrader]

johnAshpool... I did notice that too. It's remarkable. Have you seen his hour long talk on Vimeo? Google "Deutsch optimism vimeo" to find it. I didn't notice any mistakes in that talk either. Amazing...

[@annabago8621]

I love this.

[@mrdrsir3781]

Wizards did it!

[@LadyTink]

Hey TOS, I wasn't expecting to see you here ;3

[@SpinyNormanDinsdale]

I remember when my friend would explain how Santa Clause exists by adding more magical powers to his arsenal. "He CAN get into houses with no chimneys because he turns into fairy dust and blows under the door crack!" That's still a pretty darn good theory!

[@udaypsaroj]

12:30

[@kcjaymes]

Is it wrong to think, in regards to what was said at the beginning of the video about mans progress before the scientific rev., that it could have been like acceleration, in that we advance with a constand acceleration, so your velocity has constantly increased. so there was energy behind or advancements it just took time for there to be a very visible rate of development?

[@christopherhamilton3621]

Not wrong, no, but the other implied lesson is that too few people keep up with the process of learning & searching. If more people thought more deeply about ‘what else has to be true for this to be true’, we’d be in better shape by now than we presently are….

[@bajan13ken]

I found it easier, because he talks slow :) but the point was that "hard to vary" explanations are truthful, because not only are they testable, but, they follow logically (he didn't mention "logic" but that's what I inferred).

[@ScienceAppliedForGood]

It was a good explanation.

[@nouranmahmoud4688]

Thanks

[@theIraqiAtheist]

great video

[@andymartin2571]

I generally like Ted Talks and think Dr Deutsch is fanatastic, but they really should have rolled a podium out for this speaker, to hold his notes. It would have been less distracting for him and the viewer.

[@martinguila]

+Andy Martin But there is a podium there whith wheels and all for him to use. I didnt find him holding the papers distracting though.

[@muscutt]

It looks like there is a podium there, although he is not using it

[@edgregory1]

Lectures are for listening not watching generally.

[@TechyBen]

You can go even further than stating "explanation" and put it down to "frequency and correlation". There is a measured frequency and variable correlation that is tied to both the rotation of the earth it's tilt and the years progressions (etc) that have measurable effects on seasons. This is where the value in a testable claim often is.

[@yonaoisme]

no. this is precisely what he rejects. frequency and correlation will never give you new knowledge, only more information

[@karanchanaya2981]

Hope your well Mr Deutsch an Family.

[@rajarshibose5122]

Amazing..

[@roidroid]

Google gives me No results found for "The dour will be with us always." what did you mean to type?

[@Vashstampede]

I enjoyed this guys humor.

[@LarryJeffery]

Picked up the book by accident blew me away

[@G11713]

Regarding the prehistoric ancestors... monoliths?

[@enomikebu3503]

Super explicit!

[@LennyBound]

Beautiful.

[@EmperorsNewWardrobe]

10:01 Greek myth explanation of the seasons

[@johnAshpool]

Did anyone notice that during nearly 20 minutes of speech, he didn't make a single verbal mistake?

[@biljanapercinkova318]

He is reading.

[@christopherhamilton3621]

The sign of a well rehearsed presentation, even if he has notes at his fingertips…

[@midgetsow]

I just wish explanations were more concise, I think most books/dissertations/lectures don't have an issue with varying too much.

[@pmcguinness3041]

This is important.

[@Josephus_vanDenElzen]

7:43 induction: the unseen resembles the seen? no..

[@trevjankins6642]

Great ideas. Check out V S Ramachandran's book Phantom's in the brain...

[@Chemicalogic]

Amen.

[@wolffenhaus]

Its a pretty good deal we get to argue about a subject. This is a ripe time to live .

[@AR333]

what he means by "varied" is rationalized an explanation is easy to vary" When it can wrap it's way around any outcome, i.e. can rationalize with any and all new evidence its really the same thing as unfalsifiability

[@paulbali9998]

FINALLY someone willing to question the Demeter story. lol Wizards and cavemen!

[@berg0002]

If we know that the ratio between the diameter (or, as a derivative of diameter, the radius) and the circumference of a circle is irrational, why sticking to that ratio, as opposed to finding a constant that does have its constant and real inverse value?

[@yonaoisme]

what are you talking about ?!?!

[@berg0002]

Pi

[@sohanbanad1212]

❤

[@clevelandcircle]

What a 4 minute 57 second pause that is!

[@princeofexcess]

there are some new myths that hold us back as well...

[@marianpalko2531]

2:33 One enumeration to rule them all.

[@david203]

This is three years before he started working on Constructor Theory, so I won't consider it an introduction to that new discipline.

[@yonaoisme]

obviously

[@humblestman]

infact, anger is an evolved trait, to anger is to fear and fear allows us to avoid hazards

[@kalaway]

I thought this was a great talk, but I don't know how fully I agree. If the sun revolved around the earth & wasn't in line with the equator it would theoretically have the same effect on the seasons (though obviously other issues would come up) A holistic theory that fits w/ everything else 'proven'--as long as you begin with a correct original theory--will more likely be correct. That's what I thought the title was pointing to- the ability to "prove" & then explain that wisdom for posterity.

[@DavidRutten]

@ShadowShorts, if you wish. I cannot help but disagree with pretty much all your points again. I do not think this is inherently negative, I do not believe a War only had one winner (could be nobody, could be both parties, who said War is always a non-zero-sum event?) I *am* an extremist, but not a religious one. Religion is defined as a belief in the supernatural, there's nothing in there about forcing your views onto others. Even though I have strong personal views, I'm a secularist at heart.

[@zebonautsmith1541]

I saw a slightly different talk by him. Must have been in another Universe.

[@Maxstate]

In the way that the most common denominator in all of science and progress are the establishments that make it possible for it to take manifest in the first place. Even the most basic and first of the modern (so not stone-age) scientific progressions in the history of man has been made possibly by, often but not always, some form of government or upholding of a social contract by a bigger establishment. Where I disagree with him is in his argument that all establishments bar progress.

[@chasetherushpodcast2534]

the great man

[@ErichoTTA]

David Deutsch appears a lot in these.

[@KrwiomoczBogurodzicy]

[15:04]

[@GoneHaydn]

If we would have arisen "a bit" later we would not have seen other galaxies and our cosmological theories would've been very different. Perhaps we're too late to really understand how life got started. All evidence is wiped clean. Also there's the theory that early bacteria came from space, which I think is a superfluous hypothesis. Since we can create amino acids from mixing various atoms together, and that it is what we're mostly made of -- makes evolution feel inevitable.

[@princeofexcess]

in what way?

[@KrwiomoczBogurodzicy]

[11:03]

[@jairofonseca1597]

Super genius ...

[@Lihinel]

Seems wrong, at least when phrased like that. It is seems that under favourable conditions at least some new technologies were made and preserved over time so that the space of possible new technologies (that require prior advances) became larger. But it may also be said that this process can be slowed down, halted, or even reversed at least in a region (without knowledge transfer global) under unfavourable conditions. (strict (autocratic) conservative regimes, theocracies, ludistic movements)

[@o.c.2470]

I give great acknowledgements to David's retrospect on reality. It is an elegant and simple way to establish a norm to reality. The idea of that which is hard to vary remains constant in the perception of reality, is understandable and simple. However, I must humbly interject with establishing a "norm" statement to reality. It is precisely what ancient civilizations attempted to do; and modern civilizations as well. One thing "reality" has shown us is that it is not understandable in human conception yet. Quantum physics is an example of a knowledge of science that goes far beyond our imagination. This knowledge has led us to the capacity to know that in order to understand a physical reality, we must first acknowledge the lack of one in our human language. In short terms, this standard of hard to vary equals reality, like many others in the past will also be proven incorrect. In the words of Albert Einstein: Reality is merely an illusion, albeit, a very persistent one"

[@davidhepburn937]

You're missing his point. He's not saying that hard to vary equals reality. He's saying that knowledge is created through the process of seeking good explanations; and a good explanation is one that is hard to vary. He would disagree with your assertion that quantum physics "goes far beyond our imagination". He would say that's tantamount to an appeal to the supernatural. If you read his book, The Beginning of Infinity, you'll have a better understanding of his thesis.

[@vortical911]

If Santa can turn into fairy dust, what other remarkable abilities does he possess? This is an easily-variable explanation :). Maybe Santa simply has the ability to pass through transparent objects, such as windows!

[@joelgullick1245]

No, you've all got it wrong. I think what he was saying is that understanding is vastly different from experience. One requires observation the other requires both observation and reason...

[@jakepr]

i am dubbing this the "nerd war cry" his entire attitude is "bitch, sit down - this is how it is"