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JOHN GRUBER, This is 14 .01.

I'm John Gruber, and this is microeconomics.

Today I want to cover three things.

I want to talk about the course details.

I want to talk about what is microeconomics, and then I'll start the substance of the course by talking about supply and demand.

A couple of the points about the course.

The course will have a distinct sort of policy angle to it.

I sort of do economic policy as government policy is my thing.

So I think it's what makes economics exciting.

And it sort of offers, I think, an interesting angle to understand why we're learning what we're learning.

I think sometimes in an intro class, it's sort of hard to understand why the heck you're doing things.

However, that's just sort of a slight flavor.

If you're really more interested in this, I teach a whole course called 1441.

I'm not teaching it this year but it'll be taught by a visitor in the spring,

Kristen Butcher from Wellesley, and I'll be teaching it next year, that dives much more into these policy issues.

So I'm going to use government policy as an organizing theme, but it won't be the dominant theme of the class.

Finally, three points about my teaching style.

I don't write everything in the board.

We're not in high school anymore.

You're actually responsible for what I say, not what I write.

Partly that's because my handwriting is brutal, as you can tell already.

So what that means is, please, please do not be afraid to ask me what the hell I just wrote on the board.

OK, there's no shame in that.

Don't just lean to your neighbor and say, what the hell is writing the board?

Like, ask me.

Because if you can't read it, I'm sure someone else can't read it.

So feel free to ask.

And in general, please feel free to engage with questions in this class.

The other point of my teaching style is I talk way too fast.

And the longer I go, there's a mathematical function, which is the longer I go without interruption, the faster I speak until I just spin off.

OK?

So basically, please ask questions.

If anything's not clear or you just want to ask a question about some related tangent or whatever, please feel free to do so.

You might think, how would that work in a class this big?

There's always way too few questions, even a class this big.

So never be afraid that it'll slow me down or whatever.

Ask a question.

We have plenty of time in the class.

And you'll be doing your classmates a favor, because it'll slow me down.

Finally, last point, I have this terrible tendency tendency to use the term guys in a gender neutral way.

So this class I like to see looks like it's a fairly healthy representation of both males and females.

When I say guys, I don't mean men.

I mean people.

So women don't take it personally.

Guys means economic agents.

It means people.

It doesn't mean men.

It's just a way, just a bad tendency.

Drives my wife crazy.

But I've decided better to just apologize up front than try to fix it throughout, which is impossible.

OK, so let's talk about what is microeconomics.

OK?

So fundamentally, microeconomics, how many people took AP high school econ?

OK.

How many people, for how many people was it taught really well?

OK.

That's about right.

That's why I did my high school online class.

That's the answer I wanted to hear.

OK.

So tell your friends still in high school who are taking high school econ, if your high school econ teacher isn't great,

tell them to go on edX and take the class and help out your friends still in high school.

OK, so what is microeconomics?

Microeconomics is the study of how individuals and firms make decisions in a world of scarcity.

Scarcity is what drives microeconomics.

OK?

Basically, what microeconomics is is a series of constrained optimization exercises.

where economic agents, be they firms or individuals, try to make themselves as well off as possible, given their constraints.

Yeah?

Will this cover your rationality?

I will, but not as much as I should.

Essentially, we have another course in the department called 1413, Behavioral Economics, which gets into that much more.

I will sprinkle it throughout, but not as much as I actually believe in it.

In other words, the way we think about economics is it's best to sort of get the basics down before

you start worrying about the deviations.

Find it better to climb the tree before you start going out in the branches.

OK, so basically, what this course is then about is it's about trade -offs.

It's about how do you, given that you're constrained, how do you trade off things to make yourself as well off as possible?

And behind this notion of trade -offs is going to be, I'll say about 100 times,

this is the most important thing in the course, so just ignore that.

But this is one of the most important things.

I'll say one of the most important things in the course is the notion of opportunity cost.

Opportunity cost is a very important concept that we teach.

So the first concept we teach,

which is that every action or every inaction has a cost and that you could have been doing something else instead.

So if you buy a shirt, you could have bought pants.

If you sit at home and watch TV, you could have been out working.

Everything you do has a next best alternative if you could have done instead.

And that is called the opportunity cost.

And that's a critical concept in economics.

And that is why, in some sense, we are called, referred to casually, as the dismal science.

Economics are referred to as the dismal science.

First of all, I'm flattered we're considered a science.

But we're called the dismal science because our whole point is that nothing is free.

There's always a trade -off.

There's always an opportunity cost.

Anything you do, you could be doing something else instead.

And your constraint optimization means you're going to have to pass up one thing to do another.

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Now some may call it dismal, but as a former MIT undergraduate, I call it fun.

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And this is why I think MIT is the perfect place to be teaching economics.

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Because MIT engineering is all about constraint optimization.

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That's what engineering is.

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And economics is just the principles you learn in engineering applied in different contexts.

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So if we think about the 2007 contest, that still exists with the robots?

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2007?

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Yeah.

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The 2007 contest, those of you who know,

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is a contest where you're given a limited set of materials and you have to build a robot that does some tasks,

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like pushing ping pong balls off a table or something like that.

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That's just constrained optimization.

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It's got nothing to do with economics, but it's constrained optimization.

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So just think of microeconomics as like engineering, but actually interesting.

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So think of microeconomics as engineering, but instead of building something to push a ping pong ball off tables,

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you actually build people's lives and businesses and understand the decisions that drive our economy.

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So it's the same principles that you could think of for your engineering classes, but applied to people's lives.

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And that's why, in fact, modern economics was born in this room, either this room or 26 -100, by Paul Samuelson in the 1940s and 50s,

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who wrote the fundamental textbook that that gave birth to modern economics,

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because he was here and applied the kind of engineering principles of MIT to actually develop the field of modern economics.

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What we'll learn today was developed at MIT.

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So it's a great place to be learning it.

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Now, with that as background, any questions about that?

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About what is microeconomics?

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OK, with that as background, let's turn to the first model we'll talk about this semester, which is the supply and demand model.

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supply and demand.

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Now, the way we're going to proceed in this course is going to drive you crazy.

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Because we're going to proceed by teaching very, as the very first question pointed out, by teaching very simplified models.

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We're going to essentially, what is a model?

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A model is technically description between any two or more economic variables or I need two or more variables.

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But unlike the models you use in all your other classes, these aren't laws, by and large.

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They're models.

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So we don't have a relationship between energy and mass, which we can write down.

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It's a law, and we're done.

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We have models which are never 100 % true, but always pretty true, pretty being somewhere between 10 % and 95 % true.

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So basically, the idea is to make a trade -off, we want to write down in our models a set of simplifying assumptions

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that allow us with a relatively small set of steps to capture relatively broad phenomena.

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So it's essentially a trade -off.

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On the one hand, we'd like a model that captures as well as possible the phenomena in the real world, like equals mc squared.

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But we want to do so in the most tractable possible way

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so that we can teach it from first principles and don't need an hour to teach every single insight we have.

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So basically, in economics, we tend to resolve that by erring on the side of tractability.

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That is why I can teach you the entire field of microeconomics, which is really sort of macro is kind of a fun application.

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Micro is really economics.

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I can teach you the entire field of microeconomics in a semester

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because we're going to make a whole huge set of simplifying assumptions to make things tractable.

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But the key thing is that you will be amazed at what these models will be able to do.

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With a fairly simple set of models, we will be able to offer insights and explain a whole huge variety of phenomena.

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Never perfectly, but always pretty well.

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Generally pretty well.

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OK?

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And so that is essentially the trade -off we're going to try to do this semester.

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So the line I like is the statistician, George Box, said that all models are wrong, but some are useful.

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Now, obviously, it doesn't apply to models in the hard sciences, but in the social sciences, that's true.

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And basically, I'm going to write down a set of models like that.

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Now, with every model I write down, my goal is to have you understand it at three levels models.

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The first and most important level is the intuitive level.

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The level which you sort of understand, I call it passing the mom test.

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You can go home and explain it to your mom at Thanksgiving or at the end of the semester.

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No offense to dads.

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Just call it the mom test.

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So basically, that's the intuitive level.

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You really understand it a way that you could explain it.

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The second is graphical.

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Most of our models here will develop in a graphical framework work, using x, y graphs, that were really weak in economics,

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we think delivers a lot of shorthand power.

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And the third is mathematical.

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The mathematical is probably the least important, but it's the easiest to test you on.

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So we're going to need to know things mathematically as well.

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OK?

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So let's start by considering the supply and demand model by using the famous example brought up by Adam Smith.

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Adam Smith is sort of considered the father of economics.

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Paul Samuels is the father of modern economics.

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Adam Smith's the father of all economics.

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His 1776 book, The Wealth of Nations, did an incredible job of actually laying out the entire core of the economics field.

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No math, just words, but kind of he just nailed it.

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And he started, one of his most famous examples was the water diamond paradox.

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He said, think about water and diamonds.

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He said, start with water.

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Nothing is more important for life than water.

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It's the building block of all of life.

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Even when we look for life on other planets, we always start by looking for water.

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Now think of diamonds, one of the more frivolous things you can buy,

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certainly irrelevant to leading a successful or happy or productive life or any life.

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Yet, for most of us, water is free and diamonds are super expensive.

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How can this be, Adam Smith asked.

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Well, the answer he posed is that what I first described was just demand.

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That is, we demand lots of water.

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We demand fewer diamonds.

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But we have to match that with the concept of supply.

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And the supply of water is almost infinite, while the supply of diamonds, maybe not naturally.

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Maybe it's through decisions of various businesses.

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But it's somewhat limited.

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So basically, what he developed is what we call the supply and demand scissors.

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that you can't just think of supply or demand in isolation.

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You have to put them together if you want to explain the real world phenomenon we see,

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like the fact that water is cheap and diamonds are expensive.

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So let's talk about an example.

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So there's one graph that was handed out in the back, which is let's talk about the market for roses.

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So in the market for roses, we have a demand curve and a supply curve.

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So what we have here, this is the kind of xy graph we're going to look at all throughout the semester.

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On the x -axis is the quantity of roses.

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On the y -axis is the price of roses.

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The blue downward sloping line is the demand curve.

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Now, what I'm going to do here, I'm Just give me an overview.

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We are going over the next five or six lectures, dive into where this demand curve comes from.

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We'll go to first principles and build it back up.

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But for now, we need to know about demand curve is it simply represents the relationship

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between the price of a good and how much people want it.

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Therefore, we assume it is downward sloping.

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At higher prices, people want less of the good.

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And we'll derive where that comes from shortly, starting next lecture.

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But for now, I think it's pretty intuitive that if the price of roses is higher, people want fewer of them.

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And that's why it's downward sloping.

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OK?

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That basically, as the price of roses goes up, people want fewer roses.

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The yellow curve is the supply curve.

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Now after we've derived the demand curve, we'll then go and spend about 12 lectures deriving the supply curve.

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That's a bit harder.

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But once again, we'll start from first principles and build it up.

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For now, you just need to know is that's how much firms are willing to supply given the price.

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So basically, as the price goes up, firms want to produce more roses.

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The higher price means you make more money, so you want to produce more of them.

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This is slightly less intuitive than demand, but we'll derive it and explain how it can be.

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But for now, just go with the basic intuition that if you're making something, and you can sell it in the market for a higher price,

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you're going to want to make more of it.

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OK?

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And that leads to the upward sloping supply curve.

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Where the points meet is the market equilibrium.

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Where supply and demand meets is the market equilibrium.

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OK?

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That is the point where both consumers and producers are happy to make a transaction.

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Consumers are happy because they are on their demand curve is the 0 .600, is the 0 .3 dollars and 600 roses.

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That is, they are willing to buy 600 rows at $3.

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Producers are happy because on their supply curve is the same point.

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They are willing to supply 600 rows at $3.

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That is the one point where consumers are happy and producers are happy.

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Therefore, it's the equilibrium, highly non -technical.

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But that's the basic intuition.

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The point at which they're both willing to make that transaction, the point at which they're both satisfied with that transaction is the equilibrium,

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which in this case

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This case is $3 per rose and 600 roses.

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Now, this raises lots of questions.

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Where do the curves come from?

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How does equilibrium get achieved?

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Why the heck do we give roses?

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These are a bunch of questions.

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We will come to all these questions over the next set of lectures.

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But the basic thing is to understand this intuition of Adam Smith's supply and demand model.

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OK?

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Questions about that?

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OK.

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OK, now, this model also raises another important distinction that we'll focus on this semester, and it's easy to get mixed up.

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So I want you to, if you're ever unclear, I want you to ask me about it.

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And that's the distinction between positive versus normative analyses, positive versus normative.

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Positive analyses is the study of the way things are, while normative analyses is the study of the way things should be.

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Positive analysis is the study of the way things are, while normative analysis is the study of the way things should be.

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Let me give you a great example, which is eBay auctions.

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Auctions are a terrific example.

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They're like the textbook example of the competitive market.

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You can see it in your head.

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Demand comes from a bunch of people going on and bidding.

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People who want it more bid more.

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So you actually get a demand curve.

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The higher the price, the fewer people you're getting to bid.

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Supply is how many units of it are for sale on eBay.

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You bid until those two meet.

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And then you have a market equilibrium at that bidded price.

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Now, one example of an eBay auction that got a lot of attention a number of years ago, early in the days of eBay,

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was someone offered their kidney for auction.

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They said, look, I got two kidneys.

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You only need one to live.

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There are people out there who need a kidney.

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I'm putting my kidney on eBay for auction.

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And what happened, bidding went nuts.

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It started at $25 ,000.

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It climbed to $5 million before the auction was shut down.

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And eBay decided they wouldn't allow you to sell your body on eBay, bodily parts on eBay.

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OK?

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OK?

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So this raises two questions.

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The first is the positive question.

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Why did the price go so high?

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So what's the answer to that?

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What's the answer to the positive question?

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Somebody wants to be kidney.

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OK.

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Good answer, but let's raise hands and give answers.

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That's part of it.

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Yeah?

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Low supply, high demand.

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Demand is incredibly high, because I die without it.

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Supply is low, because not a lot of us are willing to sell their kidneys on eBay.

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OK?

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OK?

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So low supply, high demand led to a high price.

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Adam Smith at work.

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That's the positive analysis.

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OK?

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But then there's the normative question, which is, should you be allowed to sell your kidneys on eBay?

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That's the normative question.

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The positive question is, what happens if you do?

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The normative question is, should you?

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Now, the standard economics answer to start it would be, of course you should.

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We're in a world where thousands of people die every year because there's a waiting list for a kidney transplant.

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And these are people who would happily pay a lot of money to stay alive, I presume.

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Meanwhile, there's hundreds of millions of people walking around with two kidneys who only need one.

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And many of these people are poor, or, and lives could be changed by being paid a million dollars for their kidney,

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and might be happy to take the risk that one kidney will be fine, as it is for most everyone for most of their life,

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in return for having the life -changing payment from a stranger.

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So economists would say, look, here's a transaction that makes both parties better off.

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The person who gets the kidney gets to stay alive, and they are willing to pay a huge amount for that.

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The person who sells the kidney in most probability is fine, because almost all of us can make it through life fine with one kidney,

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and can get a life -changing amount of money that could allow them to pursue their dreams in various ways.

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So that's the standard argument would be, yeah, you should be able to sell your kidneys on eBay.

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So the question is, why not?

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Why would we want to stop this transaction?

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What are the counter arguments to that?

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Let's raise their hand.

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Yeah.

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Potentially, I think maybe the issue was because of eBay, there's no way to regulate it.

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Or you don't necessarily know people could be selling fake kidneys, per se.

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Right.

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So the first type of problem comes out of the category we call market failures.

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Market failures are reasons why the market doesn't work in the wonderful way economists like to think it should.

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So for example, this answer puts up that could be the problem of fraud.

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People might not be able to tell if they're getting a legit kidney or not.

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There could be the example of imperfect information.

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Do you know what the odds are that you can spend the rest of your life with only one kidney?

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I don't either.

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We ought to know that before we start selling our kidneys.

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There could be imperfect information.

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These are the kinds of, this is one type of problem, which is the market may fail.

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Yeah?

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The current system also helps people who are poor and have failed kidney,

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and which are people who would be completely screwed by the water in that post -discomptive.

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A second problem is what we call equity or fairness.

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Equity or fairness, which is we would end up with a world where only rich people would get kidneys.

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Currently, there's a bunch of voluntary donors and people who are in accidents who have kidneys left over.

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And those go to people on the base of where they are on a waiting list.

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It's actually a prioritized waiting list.

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It's kind of a cool one of my colleagues, Nikhil Agarwal.

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If you think about it, I'll talk a lot this semester about the imperialistic view of economics, all the cool things we can study.

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So he actually uses economic models to study the optimal way to allocate organs to individuals.

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Right now, it's just done based on a waiting list.

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But it may be that someone further down the waiting list needs it more than someone higher up the waiting list,

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because they're more critical or whatever.

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So there's various often ways to allocate.

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But certainly, often the way to allocate wouldn't be the rich guy gets it first.

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That would be unlikely to be what society would necessarily want.

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So there's an equity concern with that.

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What else?

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What other?

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Yeah?

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You might have a situation early.

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Since you know you can make money off of selling kidneys and you take advantage of people, it's very bad for kidneys.

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GARY GENSLER - Right.

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So there's sort of a third.

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It's related to fraud.

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But there's sort of a third class of failures that gets into the question about behavioral economics that was raised earlier,

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which we can just call sort of behavioral failure.

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Behavioral, it's called behavioral economics, for want of a better term, which is essentially, people don't always make decisions in the perfectly rational,

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logical way we will model them as doing so this semester.

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People make mistakes.

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That's a word we hate using economics.

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We hate saying mistakes.

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Ooh, boo, mistakes.

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Nobody makes mistakes.

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We're all perfect little economic beings.

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But we know that's not true.

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Increasingly, over the past several decades, economists have started incorporating insights from psychology into our models.

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To not just say people make mistakes, that's a lackadaisical, but to rigorously model the nature of those mistakes

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and understand how mistakes can actually happen due to various cognitive biases and other things.

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In this world, you can imagine people could make mistakes.

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They could not really sit down and quite understand what they're doing.

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And they could have selling their kidney when it's really not in their own long -term interest.

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Yeah?

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Could an example be like, if there's a family that's in extreme poverty, even though they only have one kidney,

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they might sell the other one just to give them more money for the family, per se?

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Well, I mean, in some sense, that would be, once again, if we took this factor out,

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if the market works well with its own behavioral effects, we'd say, well, you know what?

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That's their decision.

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You know, if they otherwise they starve, who are you to say?

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OK.

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But once you choose this, say, well, wait a second.

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Maybe they're not evaluating the trade -offs correctly.

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Even if there's no fraud, even if there's perfect information, they may not know how to process that information correctly.

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OK.

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But that is not standard economics.

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That's not what we'll spend a lot of time on this semester.

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But it's obviously realistic.

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OK?

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So those are a bunch of good comments, great comments.

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And then, yeah?

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Also in the elastic demand, such that people will always need kidneys for - GARY GENSLER - That won't turn out to be a problem.

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That doesn't turn out to be a problem.

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OK, and we'll come back.

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That's a great comeback.

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We'll talk about the shape of demand curves.

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We want to return to that question in a few lectures, but that doesn't actually cause a problem.

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It's just that's more of a positive thing about why the price is so high.

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But it's not a normative issue about whether you should allow it or not.

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OK?

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OK?

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So basically, these are exactly, this isn't, to me, honestly, I spend my life thinking a lot about these things.

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I think these are really interesting issues.

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But you can't get to the normative issues without the positive analysis.

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You need to do the positive analysis, you need to understand the economic framework before you can start jumping and drawing conclusions.

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That's no fun.

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We all want to jump to draw conclusions and saying, this should happen, this shouldn't happen.

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You can't do that.

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We have to be disciplined.

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We have to start with the fundamental economic framework.

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OK?

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OK?

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And basically, the bottom line, you know, I said I'll teach this course with a policy bent.

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But you have to recognize that economics at its core is a right wing science.

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Economics at its core is all about how the market knows best, OK?

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And that basically governments only mess things up.

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That's sort of the basic, a lot of what we'll learn this semester.

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As the semester goes on, we'll talk about what's wrong with that view and how governments can improve things.

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Indeed, I teach a whole course about the proper role of of government and economy.

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But the standard of economics is the market knows best.

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And that leads us to the last thing I want to talk about, which is basically, how freely should an economy function?

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Let's step back to the giant picture.

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Let's step back from a market for roses to the entire economy.

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How freely should an economy function?

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We have what's known as a capitalistic economy.

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In a capitalistic economy, firms and individuals decide what to produce and consume, may be subject to some rules of the road set by the government.

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There's some minimal rules of the road to try to avoid fraud or misinformation.

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But otherwise, we let the dice roll.

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Firms and consumers decide what to do.

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Now, this has led to tremendous growth.

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America was not a wealthy nation.

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It was not a very wealthy nation 100 years ago, 150 years ago.

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It's led to tremendous growth where we are now still in the most powerful and wealthiest nation in the world,

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largely driven by the capitalistic nature of our economy.

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On the other hand, we are a nation with tremendous inequality.

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We are by far the most unequal major nation in the world.

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The top 1 % of Americans has a much higher share

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of our income than in any other large country in the world, any other large developed country in the world.

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The bottom 99 % has less of our income corresponding than anywhere else.

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So it's led to major inequality.

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And it's led to other problems.

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It turns out that the government can't appropriately set the rules of the road to avoid things like fraud, as we saw with Enron,

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if you remember back to that, or a lot of what happened during the financial meltdown.

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It turns out it's hard to get people perfect information, et cetera.

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So we've seen the problems.

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We've grown very wealthy as a nation.

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We've introduced a whole set of problems through this system.

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Now, the other extreme is what's called the command economy.

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Rather than a capitalist economy, it's what's called the command economy.

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In this case, the government makes all the production and consumption decisions.

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The government doesn't just set the rules of the road.

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The government owns the road.

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The government says we're going to produce this many cars this year, and people can get them in some way.

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It could be a lottery, it could be waiting in line.

457

However, we decide to allocate them.

458

We're not going to let the market allocate them.

459

We, the government, will allocate them.

460

We'll allocate how many get produced and who gets them.

461

And this was the model of the Soviet Union that I grew up with.

462

This was the pre -1989 Soviet Union.

463

The government decided how many shirts, cars, TVs, everything.

464

It's sort of bizarre to think about.

465

Literally everything, the government decided how much to produce.

466

And by and large, the government decided who got it partly through corruption.

467

That is, the party members, party leaders got it first.

468

and often just through waiting in line for the remaining application.

469

Now, in theory, this ensured equity by making sure that everybody shot a thing.

470

In practice, it didn't work well at all.

471

And actually was what dragged down the collapse of the old

472

Soviet economy, was that the command model simply doesn't work.

473

Partly, there's just too many opportunities for corruption.

474

When the government controls everything, That means there's no checks and balances on the opportunity for enormous corruption.

475

The capitalist economy puts some natural checks and balances on that.

476

And partly because it turns out that it's hard to control human nature.

477

And Adam Smith had it right.

478

Adam Smith talks about the invisible hand of the capitalist economy.

479

The invisible hand is basically the notion

480

that the capitalist economy will manage to distribute things roughly in proportion to what people want.

481

And that's where folks want to be.

482

Folks who want a certain kind of car are going to want to get to that kind of car.

483

And if the government has it wrong, they're going to get upset, and it's going to lead to a less functional economy. So basically,

484

Adam Smith's view is that the invisible hand view is

485

that consumers and firms serving serving their own best interest will do what is best for society.

486

So the fundamental core of the capitalistic view is the consumers and firms serving their own best interest

487

will do what ends up being best for society.

488

And that's essentially the model we'll learn to start in this course.

489

Yeah?

490

In that definition, are we defining best for society as in everybody has the most money,

491

or everyone has the best health or the best income living?

492

What is best for society?

493

GARY GENSLER - Great, great question.

494

We're going to spend a lot of the semester talking about that.

495

For now, we're going to find best for society as the most stuff gets produced and consumed.

496

That's how we're going to find it.

497

Obviously, you've raised a set of issues about what about pollution, what about health, et cetera.

498

We're going to come to those.

499

But for the first 2 thirds of the course, best for society means what we're going to call maximum surplus,

500

which which is the most stuff gets produced at people value.

501

So that's how we're going to do it.

502

And in his view, the visual hand does that.

503

And by and large, it's a very helpful framework to turn to.

504

However, it can lead to outcomes that are not very fair.

505

So the way we're going to proceed in this course

506

is we're going to start by talking about how Adam Smith's magic works.

507

How does the magic happen?

508

How does individuals and firms act in their own self -interest

509

without caring about anybody else end up yielding the largest possible productive economy?

510

How does that happen?

511

And we're going to talk about that.

512

We'll start with demand, which is how do consumers decide what they want given their resources.

513

We'll talk about the principle of utility maximization, the idea that I have utility function, that I can mathematically write down what I want.

514

I'll have a budget constraint, which is the resource I have, and then we'll do constrained optimization.

515

We'll say, give them what I want and the resource I have.

516

What decisions do I make?

517

Boom, we get the demand curve.

518

Then we'll turn to supply.

519

And we'll talk about how do firms decide what to produce.

520

That's much more complicated, because firms have to decide what inputs to use and what outputs to produce.

521

And we'll talk about how firms can operate in very different markets.

522

There's a competitive market that Adam Smith envisioned.

523

But that doesn't always work.

524

Sometimes we get monopoly markets, where one firm dominates.

525

And you can actually have outcomes which aren't the best possible outcome, even with the invisible hand.

526

So we'll talk about different kinds of markets.

527

Then we'll put it together to get market equilibrium and talk about sort of Smith's principles.

528

And then from there, we'll talk about how it breaks down in reality,

529

different changes in reality, how there are various market failures that can get in the way.

530

Why we have to care about equity and what implications that has, about behavioral economics, about a set of other factors.

531

So that's basically how we're going to proceed this semester.

532

As I said, the lectures are important, but the recitations are as well.

533

Once we're sort of in steady state,

534

the recitations will be about half new material and half working through problems to help you prepare for the next problem set.

535

So the problem sets are going to work is the problem set that's assigned

536

will cover material that's taught up to that date.

537

So for example, problem set one is going to be assigned next Friday.

538

That will cover everything you've learned up through next Wednesday.

539

Therefore, in section on next Friday, we'll do a practice problem, which you should understand because it'll cover things we've taught in class.

540

And it'll prepare you for the problem set.

541

And we'll do that every week.

542

That about half the sections.

543

The other half of the section will be new material.

544

This Friday, this section on Friday, is all new material.

545

What we're doing Friday is cover the mathematics.

546

I don't like doing math.

547

I always get it wrong.

548

So I leave math for the TAs who are smarter than I am.

549

So this Friday, we're doing the mathematics of supply and demand and how you take the intuition here

550

and the simple graphics and actually turn it into mathematical representations, which is what you need for the problem sets.

551

That this Friday, then we'll come back on Monday and start talking about what's underneath the demand curve.

552

All right?

553

Any other questions?

554

OK.

555

I'll see you on Monday.

556

Thank you.

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このレッスンの語彙とスピーキングのポイント

このスピーキングレッスンは、動画「1. Introduction and Supply & Demand」を教材にしています。繰り返し出てくる語は次のとおりです：economic, demand, model, kidney, supply。この動画には、シャドーイング用の文が555文、単語が6045語あります。音声の長さは34:46です。話す速さは1分あたり約174語で、日常会話に近い自然なペースです。単語の86%は英語の頻出3,000語に含まれます。残りは練習の前に確認しておきましょう。

この動画の重要語彙

動画に出てくる覚えておきたい単語15語を、発音と意味つきで紹介します。

単語	発音	意味
economics 名詞	/ˌiːkəˈnɒmɪks/	経済学
kidney 名詞	/ˈkɪdni/	腎臓
curve 名詞	/kɚv/	曲線
semester 名詞	/sɪˈmɛstɚ/	学期
principle 名詞	/ˈpɹɪn.sɪ.pəl/	原理, 原則
diamond 名詞	/ˈdaɪ.ə.mənd/	ダイヤモンド, ダイヤ
equilibrium 名詞	/ɛkwɪˈlɪbɹɪəm/	均衡, バランス
auction 名詞	/ˈɔkʃən/	競売, 競り売り
lecture 名詞	/ˈlɛk.t͡ʃə/	講義
optimization 名詞	/ˌɑptəmaɪˈzeɪʃən/	最適化
fraud 名詞	/ˈfɹɔːd/	詐欺
equity 名詞	/ˈɛk.wɪ.ti/	衡平法
transaction 名詞	/tɹænˈzækʃən/	処理
mathematics 名詞	/mæθ(.ə)ˈmæt.ɪks/	数学
partly 副詞	/ˈpɑɹtli/	部分的に, 一部

動画に出てくる句動詞

単語	意味
write down 動詞	書き留める, 記す
go up 動詞	上がる, 登る
bring up 動詞	育てる
come back 動詞	戻る, 帰る
point out 動詞	指す, 指し示す
shut down 動詞	シャットダウン
sit down 動詞	座る, 腰掛ける

繰り返し練習したい文

動画に出てくる短く完結した文です。日常会話でそのまま使えます。

Will this cover your rationality?
We're going to essentially, what is a model?
Why the heck do we give roses?
The positive question is, what happens if you do?
The normative question is, should you?

この動画の文法

話し手がよく使っている文型を、動画の実際の表現とともに紹介します。

文型	動画での表現
現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している	I've decided · we've derived · have failed
受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる	be taught · is called · are called
関係詞節 who / which + 節 — 人や物について情報を加える	function, which is · throughout, which is · semester, which is

注意したい発音

話し手はwe're, we'll, don'tなど、短縮形や弱形を144回使っています。聞こえたとおりの短い形で発音しましょう。

「th」の音: mathematics /mæθ(.ə)ˈmæt.ɪks/, mathematical /ˌmæθ(.ə)ˈmæt.ɪ.kəl/, wealthy /ˈwɛl.θi/, underneath /ˌʌndɚˈniθ/
「sh」と「zh」の音: essentially /ɪˈsɛnʃəli/, auction /ˈɔkʃən/, optimization /ˌɑptəmaɪˈzeɪʃən/, transaction /tɹænˈzækʃən/, intuition /ˌɪn.tjuːˈɪʃ.ən/
長い単語（アクセントの位置に注意）: economics /ˌiːkəˈnɒmɪks/, behavioral /bɪˈheɪvjəɹəl/, equilibrium /ɛkwɪˈlɪbɹɪəm/, essentially /ɪˈsɛnʃəli/, optimization /ˌɑptəmaɪˈzeɪʃən/

日本語話者が苦手な音：

/r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: principle /ˈpɹɪn.sɪ.pəl/, behavioral /bɪˈheɪvjəɹəl/, equilibrium /ɛkwɪˈlɪbɹɪəm/, partly /ˈpɑɹtli/, necessarily /ˌnɛs.əˈsɛɹ.ə.li/
/v/ — /b/ にならないように、上の歯を下唇に当てる: curve /kɚv/, behavioral /bɪˈheɪvjəɹəl/, invisible /ɪnˈvɪzəb(ə)l/, intuitive /ɪnˈtjuːɪtɪv/, derive /dɪˈɹaɪv/
/f/ — 「フ」ではなく、上の歯と下唇で出す: fraud /ˈfɹɔːd/, fewer /ˈfjuː.ɚ/, framework /ˈfɹeɪm.wɜːk/, phenomenon /fəˈnɒm.ɪ.nən/, fundamental /ˌfʌn.dəˈmɛn.təl/

この動画での練習方法

まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
自分の声を録音して元の音声と比べます。economics, kidney, curveなどの単語に特に注意しましょう。

シャドーイングとは？英語上達に効果的な理由

シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。

シャドーイングのやり方: ステップ別の完全ガイドを読む →

シャドーイング練習: 1. Introduction and Supply & Demand - 動画で英語スピーキングを学ぶ

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このレッスンの語彙とスピーキングのポイント

この動画の重要語彙

動画に出てくる句動詞

繰り返し練習したい文

この動画の文法

注意したい発音

この動画での練習方法

シャドーイングとは？英語上達に効果的な理由