How Decision Making is Actually Science: Game Theory Explained 

Watching this in 2020. "Did you interact with anyone today?" No. No I did not.

There is a big mistake in this video. The definition of "Nash equilibrium" in the video is actually the definition for a strictly dominant strategy: "A player in a game has found A STRICTLY DOMINANT STRATEGY when they make the choice that leaves them better off no matter what their opponents decide to do.” In the prisoner's dilemma, each player has a strictly dominant strategy to confess--it's better NO MATTER what others do. A Nash equilibrium, by contrast, is when each player has a strategy that is better GIVEN what others are doing. Each person is doing the best to outguess others, and mutually each person is playing a best response. Here's an example to illustrate the difference. Do you drive on the left side of the road or the right? There is no choice better for you "no matter" what others do. Your best choice is to match what others do: you drive on the left if others do, and you drive on the right if others do too. This game does not permit a strictly dominant strategy. But there are two Nash equilibria--when everyone drives on the left, or everyone drives on the right. Very few games have strictly dominant strategies. In contrast, every game* has a Nash equilibrium (*under certain conditions) Nash proved the existence of the equilibrium in his doctoral thesis at Princeton, and that is work for which he was recognized with a Nobel Prize and is the subject of the book/movie "A Beautiful Mind." I mostly liked this video and the Shapley value example is good. But the definition of the Nash equilibrium is a big error--perhaps include a note or annotation?

"Did you interact with anyone today?" ha... ha...

Love how you break-down what is common sense to most.. it really forces me to understand why I think a certain way in situations where I'd normally think automatically

If I were a betting man I'd say that there is at least one comment in here referencing Matthew Patrick.

This is probably one of the more concise, bitesize videos on understanding game theory, very helpful.

I'm glad you guys went with SciShow Psych. I've been loving those vids!

Legend. Took my thoughts out of my mouth, I didn't think people has gone deep into studying this stuff wow!

HELLO INTERNET; WELCOME TO GAME THEORY!

1. "pioneered by John Nash"! John von Neumann is the father of game theory! John Nash found the equilibrium exist in a much more general class of games, but his contributions are less significant than von Neumann's. 2. (4:26) "no matter what everyone else decides to do" The whole purpose of studying game theory is that others actions affect your outcomes, and perhaps your optimal actions. You should say: taking into account what everyone else decides to do. The above condition doesn't make sense in a game theory context.

5:55 "DUMMY PLAYERS HAVE ZERO VALUE" *Luigi* would like to speak with you.

Thank you so much for the de-obfuscating a very complicated subject that to be honest I've never even started to get, until now. Thank you again!

As someone who's been stuck watching intro game theory videos for about 5 years, this is the best one I've seen to date. Very clear and concise description, Sci.

I can't be the only one expecting a matpat crossover

Ive be running this in my head to make situations work for me without even realising it was a thing.

that example reminds me of the game show Friend or Foe. two players have acquired a certain amount of money based on their performance in the game. Then at the end they make a secret decision. If they both choose the Friend option, then they split the winnings 50/50. If one chooses Friend and the other chooses Foe, then the person who chose Foe gets all the winnings and the other person leaves with nothing. If both people choose Foe, they both leave with nothing

Hank, you didn't end the video right. See according to game theory your ending was supposed to be. "And remember its just *Science*.....*Delicious Science* Thanks for *Learning*

Thank you, Hank! You totally just gave me a new title for my podcast. I'll let you know what it is once I get it rolling.

awesome vid, thank you. i'm definitely a follower of your channel now.

Very very good demonstration of SIMPLE Game Theory. A bit fast paced for a beginner, IMO, but straight to the point and easy to comprehend! Awesome video.

This is an amazing explanation, great video!

Game Theory was one of the best classes I took last semester, loved it. I'm planning on taking Advanced Game Theory this year :D

Excellent video on the basics of Game Theory. My 17 year old learned a lot from it. It may also be worth mentioning that Game Theory is put to good use by economists, military strategists, and policy strategists. Differential Games are more difficult to axiomatixe and compute, but often more accurately reflect real world situations. Military strategists generally use Differential Game Theory, as situations are often continuously changing.

I had to make a presentation on Game Theory. Your video really helped me to understand the concepts. Thank You!

"Did you interact with anyone today?" I don't like your tone there hank. Feels a little personal.

Great video on explaining the basics of Game Theory! Would you ever do a part two which explained the Normal Form vs. Extensive Form, further exploration of the Nash Equilibrium, or even the math behind certain ideas like the Cobb-Douglas utility function?

That was GREAT. Keep doing what you are doing! :)

I've studied a lot of game theory and this is one of the best introductions I've seen to these game types. One small thing, a Nash Equilibrium is achieved when no player can improve their result by changing strategy. As the brief annotation mentioned, you described a Dominant strategy. Curious viewers should look into optimal strategy for Prisoner's Dilemma in an iterated game (ie. multiple rounds of the same decision). It may be the best mathematical model available for the axiom "It doesn't matter if you win or lose, it's how you play the game."

Von Neumann and Morgenstern pioneered/created Game Theory in the 1920s-1940s. Nash made important contributions.

The only thing I could think of was "Zero Escape: Virtue's Last Reward". It's a great game based on the prisoner's dilemma. Great video, as always!

Thank you for that kind of a inner information which also explains how the system can be settled by someone intending to set one.

I ❤Hank Green. I especially love whenever Hank is amused by the content he’s delivering - and here I’m thinking of a (SciShow?) episode where he talks about ‘most dangerous chemicals’, he’s hilarious. I also love any interaction between Hank and my other man-❤, Phil Plait.

Can we do a part 2 to this. I love this. :D

I noticed two errors in the video: 1. Game theory was pioneered by von Neumann and Morgenstern in their 1944 book. John Nash came later. 2. The definition given of a Nash equilibrium is actually a dominant strategy. A Nash equilibrium is more general.

Awesome explanation using simple example and words!

Love it! Discovered you with Crash Course - Psychology. So surprised to find you here! Great!

Loved this video. Videos like these have made me change the way i used to think about of Maths!

That's just a theory, a GAME THEORY! Thanks for watching!

the prisoner dilemma made me remember a scene from The Dark Knight, that ship scene. Just sharin

Great video, thanks for the explanation!

Can you do one on cerebral aneurysms? I had one rupture at 19 and would love to learn more!

Sun Szu says to protect yourself against defeat is in your own hands but to defeat the enemy is the hands of the enemy himself so a good Worrior can garantee he protect himself against defeat but cannot garantee he defeats the enemy

Awesome video, I have learnt a lot watching this one and others from this channel.

Thank you for your great explanatory information

matpat comments incoming.

This has helped me a lot to understand the theory. Thanks!

thank you!!!! i really learned a lot from your video, ill suscribe right *click* now... do you recomend any book to continue studiyng this???

Simple and to the point! Loved it.

everybody seems to be correcting the video, so I will also join the chorus. FOr once that I can. The winning strategy in the prisoner's dilemma is to defect only if the game is played only once. If you play another version which is repetitive prisoner dilemma, the winning strategy end up TfT (tiit for tat) where each player starts to cooperate and then copies the behaviour of the other player in the previous round.

I use a running shapley value when I play chess, each piece in part of the coalition. I just didn't know what it was called, I assign each piece a value and keep a tally of how much each piece contributes towards capturing other pieces and advancing my position. Allowing me to make sacrifices that appear to be me losing but are me just positioning my opponent a certain way.

I want to study game theory now. Thanks for the video. 😊

The lecture is just a tour on Game and a good introduction. We can dig deeper

Holy shit this was the most interesting Scishow episode I've seen in ages. I need to look into this more!

I instinctively recoiled seeing this in my recommendations before I realized who posted it

That was very good and informative...thanks

Always interesting, thanks.

Always wondered what game theory was, this vid makes me want to study it more. Very cool.

I actually thought I was clicking on a matpat video haha! awesome video though hank! :D

mega gutes Video, vielen Dank! 🤩

Thanks! I was searching for this for a long time. It was very nice

I like how they re posted yesterday's vid

I can only pray for no cringeworthy posts on this video.

thanks....SciShow...So informative

Video explanation always make better to me, thx

If you want to learn more about game theory and you like anime/manga I suggest checking out the manga Liar Game! It's pretty entertaining and it teaches you a lot. Plus it's complete, which is always nice.

Tip: Don't bake with the Cookie Monster. It doesn't work out well for your profit margins.

That was brilliant. very good explained.

plain and simple, thanks for making this video

Like Michael Scofield from Prison Break. He uses Game Theory to earn other inmates' trust and friendship for his own benefit.

MFW I don't even have to keep scrolling into the comments section to know what a lot of them are.

Thanks for the elegant explanation. It's a brilliant theory formulated by a beautiful mind.

great explanation love it

I REALLY hope it's Sci show psych. I freaking love psychology (despite only studying it on the side to computer science) but it's so damn fascinating and it just clicks with me so easily

3:14 °MatPat crying in the distance°

Thank you so much for acknowledges,.

Great Explanation

SciShow Life - Health - Psych Why not all 3 and call it SciShow People? It would help keep the videos diverse and prevent stagnation from being a (relatively) smaller field and would also keep work on the videos fresh (instead of working on videos in the same field continuously), my opinion atleast :)

8:47 - this video in a nutshell

Game theory was pioneered by John Von Neumann's paper in 1928 which completed by "Theory of Games and Economic Behavior" by Von Neumann (mathemarician) and Oskar Morgenstern (economist) in 1944. It mainly covered zero-sum games, expected utility (to deal with uncertainty, introduced in the second edition) and applications in politics, economics, and social behavior. In 1950, John Nash contributed a remarkable one-page PNAS article that defined and characterized a notion of equilibrium for n-person games. Above statements is paraphrased from Wikipedia and PNAS.

seems very impressive and wonderful interpretation.

"Safety First, Then Teamwork."

But hey, that's just a theory- a game theory! OH GOD SO MUCH MATPAT.

Great intro in to game theory. I'll do further research

Love this!!

awesome! thanks. This was great. two questions i am wondering about - 1) in competitive games when there is a chance to cooperate and get the best deal for all participants ( like OPEC, why didn't they all collude and let the price rise significantly rather than producing Oil near max. output). difference from the prisoners dillema is that they can make contact with other parties and oil output inspections could establish trust. That would have been the best outcome for the producers. what am i missing ? 2) any link / source to shapley values of IMF, UN or NATO ?

Hmm..Prisoner's Dilemma is basically like the part in The Dark Knight where The Joker offers the chance to people on the two ships to either bomb each other by a certain time, or they both get bombed.

I'm glad I made the decision to watch this. Thanks Hank! #scishowrules

I feel million times smarter now. Thankyou.

But hey! Thats just a theory A GAME theory, thanks for watching!

But hey, that's just a theory: A GAME THEORY!!!!

Well explained thank you

Thank you so much! 💗💖

0:50 : - Like, did you interact with anyone today? - Me: ...... - Well you can probably..

For more on the Prisoner's Dilemma, play Virtue's Last Reward. B for Betray

The conclusion was amazing.

I think it says a lot about our society that of the many times I have heard about the prisoner's dilemma, no one has ever mentioned that not only does it convict a pair of innocent people with the 'game' mentality, if one person is guilty and the other is innocent the innocent person goes up the river for 10 years.

But hey, that's just a theory.

"Did you interact with anyone today?"....ahh life pre-covid.....

Awesome thanks !!

Beautifully Explained!