未来時制と貯蓄(メモ)

Tim Bowler”Why speaking English can make you poor when you retire” http://www.bbc.co.uk/news/business-21518574


英語を話す人よりも中国語(マンダリン)、マレー語、ヨルバ語を話す人の方が老後より多くの金を貯めているよという話。イェール大学の行動経済学者Keith Chenの研究を中心に。
ところで行動経済学については、


Wikipedia
http://en.wikipedia.org/wiki/Behavioral_economics
Richard H. Thaler and Sendhil Mullainathan “Behavioral Economics” http://www.econlib.org/library/Enc/BehavioralEconomics.html


Keith Chenについては、


http://faculty.som.yale.edu/keithchen/
Geoffrey K. Pullum “Keith Chen, Whorfian economist” http://languagelog.ldc.upenn.edu/nll/?p=3756
Dan Stein “Economics and linguistics merge in study” http://yaledailynews.com/blog/2011/11/15/economics-and-linguistics-merge-in-study/


ここで参照されているKeith Chenの研究は


M. Keith Chen “The Effect of Language on Economic Behavior: Evidence from Savings Rates, Health Behaviors, and Retirement Assets” http://faculty.som.yale.edu/keithchen/papers/LanguageWorkingPaper.pdf

記事に曰く、


Prof Chen divides the world's languages into two groups, depending on how they treat the concept of time.

Strong future-time reference languages (strong FTR) require their speakers to use a different tense when speaking of the future. Weak future-time reference (weak FTR) languages do not.

"If I wanted to explain to an English-speaking colleague why I can't attend a meeting later today, I could not say 'I go to a seminar', English grammar would oblige me to say 'I will go, am going, or have to go to a seminar'.

"If, on the other hand, I were speaking Mandarin, it would be quite natural for me to omit any marker of future time and say 'I go listen seminar' since the context leaves little room for misunderstanding," says Prof Chen.

Even within European languages there are clear grammatical differences in the way they treat future events, he says.

"In English you have to say 'it will rain tomorrow' while in German you can say 'morgen regnet es' - it rains tomorrow."

「未来」が文法的に明確であるかどうか。或いは「未来」と「現在」の差異が文法的に明確に表現されているかどうか。それでは何故「未来」が明確に区別されていないと金が貯まるのか。それは、貯蓄という行為は「現在」の自己と「未来」の自己との同一性の等価性を前提としており、それは文法的に「現在」と「未来」の区別が明確でなく、互換的でさえある場合の方がより強く意識されるということ?

Speakers of languages which only use the present tense when dealing with the future are likely to save more money than those who speak languages which require the use a future tense, he argues.

So how does a mere difference in grammar cause people to save less for their retirement?

"The act of savings is fundamentally about understanding that your future self - the person you're saving for - is in some sense equivalent to your present self," Prof Chen told the BBC's Business Daily.

"If your language separates the future and the present in its grammar that seems to lead you to slightly disassociate the future from the present every time you speak.

"That effectively makes it harder for you to save."

文法のほかにも、多くの文化的・経済的因子があるだろうという批判に対して、

It is a point Prof Chen acknowledges, saying "I completely agree, it seemed far-fetched to me when I started doing this research as well."

But he says his research has controlled for all these factors, by concentrating on nine multi-lingual countries: Belgium, Burkina Faso, Ethiopia, Estonia, DR Congo, Nigeria, Malaysia, Singapore, and Switzerland.

"You can find families that live right next door to each other, have exactly the same education levels, exactly the same income and even exactly same religion.

"Yet the family that speaks a language that doesn't distinguish between the future and the present will save dramatically more," he says.

In Nigeria, for example, Hausa has multiple future tenses, while Yoruba does not.

"You can find Nigerians who speak Hausa and Yoruba who live next to each other and yet have radically different savings behaviour."

Chen氏は老後の貯蓄のほかに、喫煙率や肥満率も調べており、未来の弱い言語の話者の方が喫煙率も肥満率も低いと論じている。しかし中国大陸は喫煙率が高い社会である。これは氏がシンガポールを調査対象にしたことと関係があるだろう。つまり、文法よりも、喫煙に対する法的・社会的規制が強いか弱いかに関係しているのでは?
ダーハム大学の行動経済学者Morten Lau*1の批判;

But Morten Lau, director of Durham University's Centre for Behavioural Economics, says the factors which affect how much people save have little to do with language.

"In my own work with savings, it is interest rates that determine savings behaviour."

Prof Lau says there are often significant differences within language groups, and just using the average of these results in analysis can prove problematic.

"You have to be careful the inferences you make from correlations like these. It is very difficult to control for multiple factors."

"For instance, in our own research in Denmark, we found that male smokers wanted a higher interest rate on their savings than did non-smokers. But that this did not apply to women smokers."

貯蓄率に影響を与えるのは(文法よりも)利息率だ。(リフレ派であろうとなかろうと)大方の経済学者はこちらの方に妥当性を感じるのではないか。
Morten Lauについては、


http://www.dur.ac.uk/business/faculty/staff/profile/?id=2691


また彼の研究は


Glenn W. Harrison, Morten I. Lau and E. Elisabet Rutström “Individual Discount Rates and Smoking: Evidence from a Field Experiment in Denmark” Newcastle Discussion Papers in Economics, 2009
http://www.ncl.ac.uk/nubs/assets/documents/workingpapers/economics/WP03-2009.pdf


生に対する言語の規定力はそんなに強いものじゃないという言語学者John McWhorter*2の批判;


Linguist John McWhorter, of Columbia University, says any influence a language's structure has on the way its speakers see their world is extremely subtle.

"The extent to which the language shapes the thought is tiny. We're talking about milliseconds of reaction.

"None of it has ever been proven to have anything to do with how people see the world or experience life.

"It's a tempting idea that simply doesn't make any sense."

Also, he says, some languages have been wrongly classified, thus undermining the statistical correlations.

"Russian, and languages like it, are a lot more like Mandarin than Keith Chen thinks."

Despite his critics, Prof Chen insists his findings are robust.

"What's remarkable, is when you find correlations this strong and that survive so many aggressive sets of controls, it's actually hard to come up with a story of what else might be causing this."

So what does Prof Chen think of the idea that if he is right, then English speakers who want to start saving more for their retirement, should start talking entirely in the present tense?

"It actually seems like encouraging yourself to think in the present tense makes it a little bit easier to engage in self-control."

See also http://d.hatena.ne.jp/sumita-m/20110214/1297613268