漫画でわかるEconomics入門 (The Cartoon Introduction to Economics -Volume one: Microeconomics)

The Cartoon Introduction to Economics: Microeconomics

日本語版もあった。

この世で一番おもしろいミクロ経済学――誰もが「合理的な人間」になれるかもしれない16講

PART I : THE OPTIMIZING INDIVIDUAL

Economics is about the actions of OPTIMIZING INDIVIDUALS and the INTERACTIONS between them.

• an optimizing individual is "selfish jerk"!
• the assumption in economics is that every single person is an optimizing individual.
• Optimizing individuals are people trying to satisfy their own preferences

The Big question in Microeconomics is:

Under what circumstances does INDIVIDUAL optimization lead to outcomes that are GOOD FOR THE GROUP AS A WHOLE?

In other words: When I do what's good for ME, and you do what's good for YOU, and everyone else does what's good for themselves, when are the results good for ALL OF US?

Keywords

• sunk costs
• marginal analysis: comparing similar choices (similar choicesというのがポイント)
  • companies can use marginal analysis to make pricing decisions -> profit-maximizing price
• present value
  • money today and money tomorrow can't be directly compared
  • ALL decisions involving time and money depend on the value of the interest rate!
  • 永久債のpresent value = x / r (x: 受取額 r: 利率)
• variance: measure of how far any one particular outcome is likely to be from the expected value (p. 44 の絵が分かりやすい)
  • 散らばりが大きいほうがrisky
• the law of large numbers
  • これのおかげで保険会社が成立する
• Trade
  • Theory of Comparative Advantage (比較優位の法則)

人・定理

• the invisible hand (神の見えざる手)
  • caused by ADAM SMITH in 1776
• Diversification: "Don't put all your eggs in one basket"「卵を１つのカゴにもらない」
  • JAMES TOBIN won the Nobel prize in 1981.
• Adverse selection: "Buying an individual health insurance policy (in US) can be a real pain in the neck" 「逆選抜：売り手と買い手の情報比対称性から生じる市場の失敗」
  • GOROGE AKERLOF shared the Nobel prize in 2001.
• If there's nothing to stop people from trading, Nothing will stop people from trading.: The Coase theorem : "If people aren't trading, something must be stopping them"
  • RONALD COASER won the 1991 Nobel prize for this idea.

PART II: STRATEGIC INTERACTIONS

The bottom line - and this is true Everywhere in Game theory- is: "INFORMATION MATTERS"

Economists who study games focus on two questions:

1. Can we predict the outcome of a game?
2. Is the predicted outcome good?

A good outcome should at least be Pareto efficient.

An outcome is Pareto inefficient if it can be Pareto improved. An outcome is Pareto efficient if it cannot be Pareto improved.

Keywords

• Game theory
• Cake cutting problem
• Pareto efficient, Pareto efficiency
  • named after Vilfredo Pareto
• Pareto improvement
  • if switching makes at least one person better off AND makes nobody worse off.
• The Prisoners' Dilemma （囚人のジレンマ)
  • Two things makes this special. The 1st is that each player has a DOMINANT STRATEGY if they just want to get out of jail as soon as possible. The 2nd thing is that Dominant strategies lead to an outcome that is BAD for BOTH PRISONERS.
  • In other words, the Prisoners' Dilemma means that when we EACH act in our individual self-interest,the outcome is BAD FOR BOTH OF US.
• Tragedy of the Commons: the generalized version of the Prisoners' dilemma (コモンズの悲劇)
• (for Auction)the Revenue Equivalence Theorem: In many circumstances, all Four of these auctions generate the same expected revenue for the seller.(オークション：どの手法で行っても売り手の利益は変わらない）

人・定理

• JOHN NASH shared the Nobel prize in 1994 for his analysis of Game theory strategies

PART III: MARKET INTERACTIONS

the Formal definition of a Competitive market is: A market with lots of buyers- each one small relative to all the buyers together- and lots of sellers- each of small relative to all the sellers together.

In other words, in a Competitive market, each buyer and each seller is like one single grain of sand. And the market itself is like a huge beach that has lots of grains of sand and no big rocks! (p. 119 のイメージ図がわかりやすい)

In a competitive market, each buyer or seller is too small to influence the entire market. -> Game theory is all about strategic interactions, however Price theory has no strategic interactions. (理想的な市場/Competitive markets are all the same)

The theory of Supply and Demand says that price n competitive markets are determined by two curves: a Market Supply curve and a Market Demand curve. The market equilibrium price occurs at the intersection of the curves.（需要と供給の法則)

The curves that provide the foundation of competitive markets have two totally separate interpretations. 1. You can think of them as Supply and Demand curves, or 2. You can think of them as Marginal Cost and Marginal Benefit curves. (Chapter 13. ちょっと理解が甘い)

Politicians decided that the social security tax should be divided equally between employees and employers. But tax equivalence suggest that their decision made no real difference:
The economic burden would be the same even if the whole tax were on the employers, if the whole tax were on the employers.->What actually determines the economic burden??

Keywords

• Competitive market (完全競争状態の市場、理想的なもの)
• the theory of Supply and Demand
• the Equilibrium price
• Elasticities: measures how changes in one variable affect a different variable. (弾力性)
  • the Price Elasticity of demand
  • the Price Elasticity of supply
    • The less elastic side bears more of the tax burden.（税金の場合、通常は買い手が多く負担することになる)

人・定理

• Every point on the market supply curve is also a point on the market marginal cost curve. The reason is profit maximization. (to give logical proof for this, you need some calculus.)
  • JOHN HICKS shared the Nobel prize in 1972 for figuring it out.
• Giving starving people MONEY instead of FOOD may sound odd, but history shows that many famines weren't caused by lack of food but by lack of money: "Lack of money is the roof ot all evil."
  • Research by AMARTYA SEN, who won the 1998 Nobel prize, showed that some famine-stricken areas actually exported food.
• Sometimes the invisible hand is invisible because it's not there.
  • JOSEPH STIGLITZ shared the 2001 Nobel prize with his much less optimistic research about the Big question.
    • More fundamental question "Under what circumstances, do people really act like optimizing individuals?" is raised.
• "Human beings are not always rational."
  • A psychologist DANIEL KAHNEMAN shared the 2002 Nobel prize in Economics: Behavioral Economics
• "Sometimes crime does pay"
  • Unexpected applications of the optimizing individual model won GARY BECKER the Nobel prize in 1992.