EigoPro 準1級読解 — The Irrational Investor

Classical economics rested on a flattering portrait of human beings: cool calculators who weigh every option and act in their own consistent interest. Markets, populated by such agents, were assumed to price assets correctly and to err only randomly. Behavioural finance, drawing on psychology, dismantled this portrait piece by piece. People, it turns out, feel the sting of a loss far more keenly than the pleasure of an equivalent gain; they cling to falling stocks to avoid crystallising regret, and stampede into rising ones for fear of missing out. The rational investor is, at best, an occasional visitor to real markets. These biases are not random noise that cancels out across a crowd. Because they are shared and systematic, they aggregate, producing bubbles that inflate far beyond any sober valuation and crashes that overshoot on the way down. The discipline's insights have proved unsettling precisely because they suggest that markets can be collectively, persistently wrong—a possibility the older theory had ruled out almost by definition. If everyone is prone to the same illusions, there may be no cool head in the room to correct the error. Yet behavioural finance is not a counsel of despair. Understanding a bias is the first step to disarming it. Investors who automate their decisions, who pre-commit to selling at set points, who deliberately court opinions that contradict their own, can blunt the very tendencies that would otherwise ruin them. The lesson is not that humans are hopelessly foolish, but that wisdom in money, as in much else, lies less in trusting our instincts than in building structures that protect us from them.

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この単元の問題を3問、解説つきで公開しています

準1級 · 読解 · 全5問

問 1

What is the main idea of the passage?

Human beings are hopelessly foolish and cannot improve their decisions.
Investors are systematically irrational, but understanding these biases lets us build structures to guard against them.
Psychology has no useful contribution to make to the study of finance.
Classical economics was entirely correct about how markets price assets.

Phrase

wisdom in money ... lies less in trusting our instincts than in building structures that protect us from them

準1級読解経済心理主旨把握

⚡ひとことで

本文の論旨は『投資家は系統的に非合理だが、バイアスを理解し自衛の仕組みを作れる』。

選択肢の解説Choice Analysis

「Investors are systematically irrational, but understanding these biases lets us build structures to guard against them.」

正解

第1-2段で人間の系統的バイアス (損失回避・群集行動) と市場の集団的誤りを描き、第3段で Understanding a bias is the first step to disarming it、最終文で building structures that protect us from them と締める。よって『系統的に非合理だが、理解して自衛の仕組みを作れる』が主旨。

「Classical economics was entirely correct」
= 古典派は完全に正しかった ━ behavioural finance dismantled this portrait と否定しており逆。
「Human beings everywhere are quite hopelessly foolish and can never improve any of their own decisions.」
= 救いようなく愚かで改善不能 ━ not that humans are hopelessly foolish と明確に否定。
「Psychology has no useful contribution」
= 心理学は無益 ━ drawing on psychology と心理学の貢献を前提にしており逆。

▦Collocation

パターン	意味	例
rest on ~	~に基づく	Classical economics rested on a portrait.
dismantle a portrait	(像を)崩す	Behavioural finance dismantled it.
less A than B	AというよりB	less in trusting instincts than in building structures
disarm a bias	バイアスを無力化する	the first step to disarming it
a counsel of despair	絶望の勧め	not a counsel of despair

❝例文

Wisdom lies in structures, not instincts.
知恵は本能でなく仕組みにある。
Behavioural finance dismantled the old portrait.
行動経済学は旧来の像を崩した。
Understanding a bias helps to disarm it.
バイアスの理解はそれを無力化する助けになる。

💡Tip · 覚えるコツ

主旨は『問題 (非合理) + 解決 (仕組みで自衛)』の両輪を含む肢を選ぶ。本文が明示的に否定する語 (hopelessly foolish / no useful contribution) を含む肢は罠。

問 2

According to the passage, how did classical economics portray human beings?

As a crowd whose individual errors always cancel out.
As emotional agents who feel losses more than gains.
As investors who routinely cling to falling stocks out of regret.
As cool calculators who weigh every option and act in their own consistent interest.

Phrase

cool calculators who weigh every option and act in their own consistent interest

準1級読解経済心理詳細把握

⚡ひとことで

古典派は人間を『あらゆる選択肢を秤にかけ一貫した利益で動く冷静な計算者』と描いた。

選択肢の解説Choice Analysis

「As cool calculators who weigh every option and act in their own consistent interest.」

正解

第1段冒頭で Classical economics rested on a flattering portrait of human beings: cool calculators who weigh every option and act in their own consistent interest と述べる。よって『あらゆる選択肢を秤にかけ一貫した利益で動く冷静な計算者』が正解。

「As emotional agents who feel their losses a great deal more than their gains.」
= 損失を利得より感じる感情的存在 ━ それは behavioural finance の発見であり古典派像ではない。
「As investors who routinely cling on to falling stocks out of sheer regret.」
= 後悔から下落株に固執 ━ 同じく行動経済学が描く非合理で、古典派像と逆。
「As a crowd whose many individual errors always cancel one another out entirely.」
= 誤りが必ず相殺する群衆 ━ 古典派は誤りを random としたが、これは市場の性質であり人間像ではない。

▦Collocation

パターン	意味	例
a flattering portrait	美化された像	a flattering portrait of humans
cool calculator	冷静な計算者	cool calculators
weigh an option	選択肢を比較考量する	weigh every option
act in one's interest	自己の利益で動く	act in their own consistent interest
price assets	資産を値付けする	price assets correctly

❝例文

Economics assumed cool, rational calculators.
経済学は冷静で合理的な計算者を想定した。
They weigh every option before acting.
彼らは行動前にあらゆる選択肢を比較する。
Agents act in their own consistent interest.
主体は一貫した自己利益で動く。

💡Tip · 覚えるコツ

『古典派の人間像』設問は第1段の定義 (cool calculators ~) を採る。第1段後半以降の『非合理な実像』はすべて古典派像の反証なので、ここでは誤答になる点に注意。

問 3

Why, according to the passage, do behavioural biases produce bubbles and crashes?

Because the biases are shared and systematic, they aggregate rather than cancelling out.
Because a small number of irrational traders mislead everyone else.
Because random errors among investors happen to coincide by chance.
Because governments deliberately encourage markets to overshoot.

Phrase

Because they are shared and systematic, they aggregate

準1級読解経済心理詳細把握

⚡ひとことで

バイアスが泡と暴落を生むのは、それが共有され系統的なので相殺せず『積み上がる』から。

選択肢の解説Choice Analysis

「Because the biases are shared and systematic, they aggregate rather than cancelling out.」

正解

第2段で These biases are not random noise that cancels out across a crowd. Because they are shared and systematic, they aggregate, producing bubbles ... and crashes と述べる。よって『共有され系統的だから相殺せず積み上がる』が泡・暴落の理由。

「Because a small number of irrational traders end up misleading everyone else.」
= 少数の非合理な取引者が皆を誤導 ━ 全員が同じ錯覚に陥ると述べており、少数原因説と逆。
「Because the random errors among investors all happen to coincide purely by chance.」
= ランダムな誤りが偶然一致 ━ not random noise と明確に否定。
「Because governments everywhere deliberately encourage the markets to overshoot.」
= 政府が意図的に行き過ぎを促す ━ 本文に無い創作。

▦Collocation

パターン	意味	例
cancel out	相殺する	noise that cancels out
shared and systematic	共有され系統的な	shared and systematic biases
aggregate	集積する	they aggregate
overshoot	行き過ぎる	crashes that overshoot
sober valuation	冷静な評価	beyond any sober valuation

❝例文

Shared biases aggregate instead of cancelling.
共有されたバイアスは相殺せず積み上がる。
Bubbles inflate beyond sober valuation.
泡は冷静な評価を超えて膨らむ。
Crashes overshoot on the way down.
暴落は下落時に行き過ぎる。

💡Tip · 覚えるコツ

因果設問は Because 節 (shared and systematic) を採る。本文が打ち消す前提 (random / cancel out) を肯定に転じた肢は典型的な逆張り誤答。

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EigoPro 準1級 読解 — The Irrational Investor

この単元の問題を3問、解説つきで公開しています

wisdom in money ... lies less in trusting our instincts than in building structures that protect us from them

cool calculators who weigh every option and act in their own consistent interest

Because they are shared and systematic, they aggregate

EigoPro 準1級読解 — The Irrational Investor