Occam's Razor - rational principles explained 

Note: The most common _misuse_ of Occam's Razor is to compare two hypotheses, one of which _doesn't_ adequately explain the observed phenomena, and the other of which _does,_ and to select the first "explanation" over the latter because it's simpler. Simplicity _with equal or better explanatory power_ is the criterion. Looking for mere simplicity _alone_ leaves "nothing exists" as the best "explanation" imaginable!

The most impressive thing about Kaplan's videos is that he can write backwards on the glass.

I just love how philosophy is talking about the nature of knowledge and this is relevant in every aspect of life.

Thank you! All the conspiracy theories floating around the interwebs drove me here. Well, actually a very smart statistician who I've been talking to about these conspiracy theories and propaganda told me to look up Occam's Razor. I'm learning how to do my own research in determining what is true and what is false by searching for the facts myself. Thank you for your in-depth explanation of Occam's Razor. Very informative.

My favorite application of this principle is when discussing stories and fiction. Very often I might question why a character didn't make a decision within a story and very often people will try to rationalize it by using the context within the story and adding conjecture for things that the story does not explain. Meanwhile, I often conclude that a character simply did not make a decision because the writer had not thought of it. Both methods of explaining things can work but I think it's often safest to assume that anything that can't be explained within a story using only what the story provides, is something that exists merely as an error in the writing.

the best presentation on youtube on "occam's razor". from 0.20 to 6.00 minutes. what clarity man ! many thanks. you deserve a standing ovation ! This video is an absolute must for all PhD students 1. every human possess an ontology model deep inside his mind 2. formal education must help every man to digout-clarify his own ontology model 3. else... ! 4. all expenditure on education in terms of money-time-efforts will go waste 5. as man becomes older , he must attempt to simplify his own ontology model as much as possible 6. he must document-publish it before he dies ! 7. he must pass it on to the next generation as legacy.

Please dont say, " you know" while explaining something......because.....we don't. I truly enjoy watching this gentleman.

If I had this type of teacher in high school to teach me a philosophy, I would understand it's principles much earlier in life.

Thank you. Movie 12 Angry Men (1957 and 1997) is the opposite of Occam's razor, it teaches us to do deeper thinking and extract as much evidence as possible, then make a decision (you can apply Occam's razor here). However, any new evidence is subject to change in our decision. This movie shows how to use our analytical abilities to avoid injustice or faulty conclusions. Most people fail to express their opinions for fear of ridicule or rejection. Many things may not be what they appear to be. I looked up the lessons of this movie on Google and it says this, "Theories of group process including: groupthink, group polarization, social loafing, social compensation and social facilitation are exemplified in the movie “Twelve Angry Men.” The impact of group process is potentially damaging and in the context of a jury must be mitigated to ensure fairness and adherence to values."

3 minutes in and I feel this guy is critically under-subbed. Great delivery and presentation. Thanks for the video!

It's important to remember occams rasor is just a tool for selecting the most probable theory which may not be the correct theory.

It's really refreshing to see the word 'fewer' used in this video. 👍

Excellent video! And I was really amazed at how easy you can write backwards, it's insane!

I enjoyed the explanation. I enjoyed even more how often he admitted he wasn't sure of something or questioned his examples. It takes intelligence to know what you don't know.

Fantastically clear explanations. I would take it that some things Occam's Razor dispenses with of course have to be brought back as evidence and understanding both increase.

One explanation is that this man practiced for extensive periods writing and drawing backwards but a simpler explanation is that the video was flipped in post

A commentor referenced Occam's Razor in a Facebook post and since I never heard of such (which surprised me at my age) that I took to the internet to try to understand how this related to the details of the post. I am glad I found this video because it was WAY more informative than other definitions or videos on RU-vid. Thank you! I really enjoy your presentation style and am interested in your other videos! Count me in as a new subscriber!

Dude, you are so intense it’s humorous. . Your videos are amazing, educational and entertaining.

I deeply enjoy these videos. they are informative, the host is friendly. it's good vibes.

The last 45 seconds or so, when you bring up tenure and how that can affect rationality 😘👌

Really interesting ! Originally came here because of a song named Occam ‘s razor and the rational principle is really intriguing !

Thanks. I was puzzled by the word RAZOR.

Opening statement of presentation opens with a false statement stating Occam's Razor says you should only believe in simple answers. NO. Occam's Razor does not state you should only believe in answers that are simple. Occam's razor states that the answer that makes the least amount of assumptions is MOST OFTEN, the correct answer. NOT ALWAYS.

From what I know Occam's Razor doesn't ask you to believe (or not) anything. It just says that simpler things are more likely to be true. It doesn't claim that they are ALWAYS true, and thus you shouldn't believe something if there's a simpler alternative. But as with probabilities no matter the % either can be true sometimes. Actually often something is simple and we believe it's true (for example that there are 4 elements that make everything - it's quite simple). But then we discover & learn more details about it, and what happens? Does it become less likely now that we know that more (unique) things are involved in the processes? No, most often learning more things lets us focus on what exactly is important for a given thing (claim, statement, theory etc...). In that process (of learning) we might discover that some of the details we've considered before are not unique or not important. For example (of the 4 elements) we discover that Earth, Water, Air, Fire are equally meaningless. To be more precise (and rational) we discover that they're ultimately made by the same things - elementary particles, and that they mostly differ by the combination of these particles and eventually some different energies (like a flame is just electrons freed from their atoms, because of energy released by some process). Occam's razor should be used (if at all) only in situations where we have very limited time & resources to investigate better, and are trying with minimum effort to get higher chances to get it right. Just because something is more popular doesn't mean it's more important or more universal ;)

Imagine how long it took this guy to learn how to write backwards so perfectly.

I came here because of the episode of House called Occam’s Razor. I think I’m agnostic because I applied Occam’s Razor to religion, without ever having heard of Occam’s Razor. Thanks for the explanation.

Thanks for the more detailed explanation. I originally heard the term in Carl Sagan's PBS series Cosmos and then again in the movie Contact. P. S. I used it in trying to figure out how you're writing backwards on a glass board. I initially thought you're either a genius who can see this in his head and transfer it to the board for us to be able to read it, or that you're really not left-handed and that you probably just inverted the video image. Because most people are right-handed I assumed the ladder. Yes?

Beautifully explained!!!!!!! Thank you, Jeffrey Kaplan.

When I was in first grade, during recess, I asked myself the question, "Why am I here?" I thought about it and decided I was too young to answer. When I was in nursery school I stole a big ring of keys. I buried them near our house. When I tried to dig them up, I could not find them. I did a lot of digging. Then I gave up and walked home. One the way I came up with a BIG THOUGHT: God knows where they are and that I did a bad thing. In college I started following God and Jesus Christ. I have had a good life and now am 72. I have some answers and still many questions. Dr. Kaplan's lectures are good and help me with thinking through things.

Occam's razor was not intended as a guideline for what explanations you should believe, it was intended as a guideline for what explanations are the preferred candidates for further testing.

That's the best explanation I've heard of Occam's Razor by tying it to ontology.

Occam’s Razor really helps me figure out which excuse I’m going to use to call in sick to work.

Thanks you for the video. I have finally, properly understood Occam's Razor. I've never seen any of your videos before but I'll be sure to hang around.

I remember a copy of the Oxford Handbook of Clinical Medicine I had where it explained the idea of Occam's razor. No matter how disparate the symptoms appear, there is usually a single disorder responsible for them all, a kind of parsimonious modelling. But then I remember it went on to say Occam would later die as a result of a combination of diabetes mellitus, congestive heart failure, pneumonia and septicemia 😆 Get it?

I don’t care about Occam’s razor anymore, This dude writing backwards is very impressive

The whole image of him and the clear board is reversed…indicated by the fact that his shirt button placket is on the wrong side for men’s apparel. Excellent video!

And that's why when you're a hammer, everything looks like a nail! Just discovered your videos - they're awesome, I've watched a few. Thanks for sharing!

I was taught that it is not a principle but a heuristic, there's a big difference in science! A heuristic is a sort of useful tool that works in many cases or a general 'rule of thumb', not an underlying absolute principle. It usually, but not necessarily and certainly not always, leads one to the correct conclusion.

I finally understood Occam's Razor thanks to YOU!!! :-)

whether God exists... that sort of thing. "You don't have to worry about any of that." You just simplified my existence! Thank you.

Just realized that Jeffrey writes everything from the backside, that is even more difficult than mirror writing! Awesome!

I enjoyed this a great deal, but also hoped to hear more about the dangers of Occam's Razor - ways in which it can be misapplied or misunderstood. I also think EVERY talk about Occam's Razor should make mention of Agatha Christie's "Murder on the Orient Express". (I realize that sentence will confuse some people.)

aside from older geologists holding on to land bridges the main reason continental drift became adopted in the 60s-70s is that they could explore undersea far better and found the fault line running down the middle of the atlantic that is obviously actively expanding and pushing the continents away from each other. so tech improvements led to a more obvious explanation for continents drifting around over time. that was the biggest clincher.

The simplest, and truest explanation is that it's more natural, instinctive, for a lefty to write from right to left, in reverse. Think of Leonardo's notebooks.

😮Re: my ‘Non Sequitur’ question below. I figured it out. So simple. Duh! … Dr. Kaplan is indeed right handed and he’s probably writing on a sheet of glass or clear plastic in front of him, and this transparent medium is between Jeffrey Kaplan and the camera (as well as us the viewers.) In the editing, the editor horizontally flips the entire presentation. Now the camera and the audience can read all of his writing as if he was writing it backwards from his POV, just for us. This also makes Kaplan look left handed. A small price to pay to present his findings as masterfully as he does. OK, everybody, carry on!

Would this Occam´s Razor be applicable to current AI models in order to get them to give only the most rational answers instead of trying to guess the next word regardless of validity?

I always thought it was a "razor" because of the decision-making: the edge is so thin that you must fall on one side of the decision or the other. Like the metaphor of "sitting on the fence" in decision-making (that is, one cannot make a decision). A razor-thin fence can not be sat upon. I hadn't thought of it as Kaplan describes, like "shaving things away". Not sure I like his explanation, though. Any one else have a thought on the razor metaphor?

THANK YOU... i LEARNED SOMETHING NEW TODAY...YAAAAY

Plate tectonics was invented and accepted by kids in my grade school in the 1950s... based on Africa and Brazil looked like they fit together.

Will Occam's razor help me answer a question i have? I'm not sure whether at 6:00 Jeffrey says "which theory to adopt" or "witch theory, to adopt"?

Very well explained... writing things backward was amazing... are you behind a glass board or is it some kind of graphics...?

This man has a super power to write backwards.

William of Ockham was an English Franciscan friar and theologian from around 1287. Therefore the accredited name Ockham is actually the town where he lived and not his surname. To call it Occam is a misspelling. Although William was accredited with the term - Entia non sunt multiplicanda praeter necessitatem (Entities must not be multiplied beyond necessity), he never used it. Instead he was accredited with the term - Non sunt multiplicanda entia sine necessitate (Entities are not to be multiplied without necessity), but this was from a fellow monk John Punch. Its almost certain - indeed evident in contemporary documents - that a number of other people used this term before William was born, so he may not have been the originator. Its been sumised and indeed bastardised in modern time to claim - all things being equal, simpler explanations are generally better than more complex one - but this may not be what was originally meant. In other words the original says (modernised) - you can't add items unless necessary. Is what it translates to. Just saying.

The very best explanation I have yet found on this topic.

he is just fantastic. i will get it in the second viewing. thanks.

Occam's razor is used to shave fuzzy logic ;-)

Captivating presentation.

5.30 The problem in your reasoning is: What we don't have in our ontology might be true and learning should be possible. If witches are true then learning and adding to our ontology would be profitable. We don't just go on what we already know, that is the point. 10.40 A lot depends on the evidence. If there was evidence of a land bridge then that would be true. I get your point that you are saying but the examples could be better

Are there any critics of Occam's Razor? I'd love to gear from people who think that OR is misused

I had occasion to defend myself in a Tribunal. The charge was that I had failed to comply with a request to provide information to an investigator to whom the task had been outsourced. I then read the statute founding and governing the organization in question. It had been amended to say that investigation and hearing of complaint could not be delegated in whole or in part. Clearly, I say, that an illegal act cannot found a basis to punish me. I listened to the response which lacked cogency as it depended upon changing the meanings of words and restricting the words to be interpreted to a preamble to a list. I was given limited time to respond as the rejoinder. Occam's razor popped into my head so I said it. Afterwards I looked to see if it was a concept raising in law. Increasingly it is. It is very similar to the plain meaning principle.

i applied Occams Razor to you writing backwards. it must be some kind of video effect. Thats far easier than learning to write backwards at the speed you are doing it.

So I got from this that Occam's razor tells you 'witch theory' is the right one to believe and that Italy looks like a shoe but Canada sounds like aboot.

I loved the ending. When you are so invested in your belief it is hard to change that belief. Interestingly scientists always talk about Occam's Razor, but they seem to forget it when creating their theories.

"it was a long walk" great content

Very interesting explanation. Btw, in which program have you edit this video?

Occam's Razor is good for first order approximations and for quick judgments, but has serious flaws if used as a truth finding method. The first example of the Germ Theory of Disease vs. Witches falls apart if the person making the decision already believes in witches. Quantum physics requires the vast majority of people to accept book-loads of math and science that they do not themselves understand, but that is not an argument against quantum physics. In other words, it can be a decent rule of thumb, but if used as law we would never have moved past "God did it" as an explanation for everything, and simple explanations of things we already assume would always take precedent over things that have been shown to be complex but true. The argument that it requires greater suppositions to overcome things that have been shown to be true is not useful when it comes to most people interpreting science. Following Occam's Razor is a perfectly good reason for religious people to not believe in evolution, for example, since it is highly complex and there is a more simple explanation already in their ontology.

I think it was the discovery of the mid Atlantic ridge that settled the score in favour of tectonic plate movement. Also they found similar geographic strata on opposite sides of the ocean, like the ones that link northern Scotland to North America.

I almost wanted to criticize this guy but writing and drawing that somewhat detailed like that I can't. There is no way I could do that good of a job.

The plate tectonics explanation works hypothetically, as an example of how Occam's razor could work. But it doesn't fit with how the history of the theory was explained in geology class. There are enough different rocks in enough places that we would expect quite a few weird coincidences to show up, just by sheer numbers. The alignment of mountain ranges, the shape of the continents, and the distribution of fossils all looked as though the continents had once been juxtaposed, with no Atlantic Ocean between them. The shape had been noticed before the Americas were all that well mapped, and by 1912 Alfred Wegener had compiled an impressive amount of evidence. But it wasn't widely believed, because there was no then-imaginable way that it could have happened. At the time, geologists would have had to postulate witches moving the continents by magic, or something equally bizarre and ad-hoc, so they didn't. Then, from the late 1940s through the 1960s, people made various measurements including mapping the depth of the oceans and measuring magnetism in rocks, which showed lots of volcanism at mid-ocean ridges and at some distance beyond ocean trenches. Once there was an explanation for continental motion that didn't involve magic, the theory of plate tectonics was accepted. There wasn't much more of the sort of evidence that Wegener had compiled. The "fixist" explanations didn't need more land bridges. Rather, the land bridges they did need were less plausible when the contours of the sea floor were known, and the mechanism of subduction and oceanic lithosphere creation had come to be explainable without recourse to magic.

The elephant in the room is "What is the definition of 'explanation'?"

Ah ha! You saw that lecture about the Great Flood too! Nice one!!!! (it's a lecture by a geologist given at Harvard - available of RU-vid) EDIT: It's actually not exactly that but about a theory for the great flood made by engineers in the 1960s that was actually valid *if plate tecnotics* is not taken into consideration. It was in that lecture that I learned plate tectonics wasn't widely accepted until the 1970s. And people still think we know everything ...

This guy is good

This video promulgates the erroneous prescription of favoring mere simplicity over explanatory power. Explanatory power is a much much more important principle than simplicity.

Bishop William of Ockham So it should be Ockham’s Razor. Occam is a brand of light bulb

Hello Jeffery, Are you still active on your channel here? It's been 5 months since you published a video on your channel.

the pink marker is so satisfying

In Vitologia, Occam's razor is a classic example of reductionism. While it can be useful in science, it often leads to a reductionist perspective and consequent oversimplification with failure to identify a multidimensional interdependence of multiple relevant factors. This kind of thinking has consequences that we have ample opportunity to observe during history. The overall picture tends to be quite ugly.

Understand these things about Occam's razor: 1. According to Walter Kaufman ( _Thales to Ockham_ ), it likely came from Duns Scotus and was repeated often by Ockham. It should be Scotus' Razor. 2. It is a probabilistic principle. The simpler argument is more likely true; it is not definitely true. Consider the explanation that the sun is the wheel of Apollo's chariot -- necessary entities are Apollo, his chariot, and its wheel. Fairly simple. By contrast, the truth requires Hydrogen, Helium, Gravity, nuclear theory (Standard model), nuclear fusion, and radiant heat &c. Not simple. But true. 3. Like all mental tools, Ockham's Razor is useful when applied properly. It is useless when abused.

So the more things you suppose, the less likely it is that something is true? Just like it's less likely that you'll throw a 6 with a die 6 times in a row vs throwing a 1 once?

Occam's Razor applied: SR and GR your relation to sidereal time is the inverse of your speed through the medium of the galaxy. O.R. applied: Effective gov't is simple and needs little rationalization.

Take A Moment Thank you for your work young man, great spoken wording is vital. Stay Safe and Stay Free ❤🎉 Share my fellow apes Stay Safe and Stay Free

I'd say that Occam's razor wasn't quite clearly explained in the witches vs tiny bugs example, namely Occam's razor doesn't need you to ALREADY HAVE things in your ontology in order to explain an issue, it needs you to be able to ADD the most obvious thing into your ontology that would fit while also solving the issue. In this case, you needn't KNOW about tiny bugs per se (no need for the microscope yet), you could observe the things already in your ontology and make a logical assumption that fits. Per tiny bugs: you KNOW there is Earth, there are mountains, there are rocks, there is gravel, there is sand and there is silt (where you cannot see the particles but you know they are there, else it couldn't behave the way it does). You also know there are whales, elephants, lions, cats, mice, grasshoppers, ants and fleas. From these two sequences it is quite logical that there very well may be TINIER BUGS, even if you can't observe them individually. Greek philosophers observed these sequences and not only presumed the bugs but also the atoms (the point where you cannot get any tinier). Per witches: you know there are people sick that are mean to other people. Those very well might be "cursed" by witches, due to their rudeness, impoliteness, wholesome meanness. Still, you also know there are many, probably much more people, that are very nice and good to other people, and they ALSO get sick. This would tell you they most likely are NOT "cursed" because there is no motive for it. Which of the two would most likely give disease to the latter and probably larger group? If you suppose the tiny bugs (since the witches don't really fit as cause), then you again look at the former (mean) group and also deduce that the bugs fit all very well (adding only tiny invisible bugs to the ontology) while witches would be the 2nd addendum thus you can ignore it. Even if you go the medieval way of thinking that evil witches cursed the good people in order to bring evil and chaos into the world, you again get the problem of already mean people getting sick. Not to mention that witches themselves got sick too and died of various sicknesses during the trials too... Back to something that does not discriminate, the tiny bugs :)

Suggestions hehe 1. give an example where Occam's razor is wrong 2. shouldn't write "Only believe explanations that are simple", it's more "When comparing two explanations, the simpler one is more likely to be correct" or something to that effect.

Are markers that write poorly on glass, and require you to write backwards better than just doing the illustrations in post-processing? My Occam's Razor says do it in post.

Question, Jeffrey. I was originally taught that there was a difference between Occam's Razor and the Law of Parsimony, because Occam's Razor said the simplest explanation was the best, and the Law of Parsimony said the simplest explanation was the Truth. I then once had a debate with someone who asserted they were the same. Isn't there a (maybe subtle) difference between the two?

An excellent explanation!

hey, you missed australia! dagnabbit how can i accept these explanations based on incomplete examples?? antarctica doesnt count, no one wants to go to antarctica anyway

Great video! Well explained and so relevant!

At the top of the blackboard, he wrote: "Only believe explanations that are simple." This is a colossal misunderstanding of Occam's razor. 😢

I’m guessing someone has commented on this before, but how is he writing backwards? If there is some form of screen between us and Dr. Kaplan, then he has to write backwards for us viewers to read it forwards.

So im trying to take this in but I can't get over this magical board he's writing on lol....is he writing backwards 🤔 or is it the board? Either way I'm impressed

Im going full starbucks pumpkin spice girl here. I literally cant even with this guy. "Only believe explanations that are simple." Then goes directly into the necessity of understanding "Ontology" and witches and germs.

I love your explanation of the study of Ontology, however, you missed 3/4 of the continents drawn, albeit mirrored.... awesome vid!

Great video

He imminently represented Occam’s razor. It’s was NOT. “You should believe explanations that are simple.” No. It was, when presented with competing explanations, you should go with the one that requires less assumptions.

Interesting. BTW, I have been working of a way to construct a graphical depiction of an ontology model (vs symbolic approaches such as OWL) and watching this gave me some additional ideas on things I can add to my methodology for doing that.

I think there is a gross classification error on saying "Occams's Razor, which is a normative, rational pattern of thought." On the contrary, this "principle" is only a guideline when we still don't have the full picture, and not by any stretch of the use of the word "Logic" can it be considered "The Most Famous Logic Principle". As a matter of fact you'll find this "principle" missing of any serious Logic textbook, handbook for practicioners, etc. Occam's advice is an invitation to we avoid one of the horns of the issue with "pure reasoning" as Kant thought us (doing some anachronist analysis here, but good ideas are sieved by constant revisiting and checking of them), not that "always" it will lead to "correct" answer.

A great explanation.

I continually debate with people who have a large group of "axioms" to draw from when they claim to use "Occam's Razor". Opinions can be glorified or destroyed by "Alternative Facts".

Interesting! Now, can you tell me how you are writing? It looks like you're left-handed and you're writing backwards. How are you doing this?