
Paul Krugman: How I work - gabrielroth
http://www.princeton.edu/~pkrugman/howiwork.html?pagewanted=all
======
amix
I think his way of doing research is the way computer scientists do research.
I.e. instead of taking a very complex programming model (like Java's or
Haskell's), most CS researchers invent their own mini languages (that in a lot
of cases are simple extensions of lambda calculus or turning machines), these
mini languages makes it much easier to reason about specific things. An
example: Java's generics were first presented in a paper that added them to a
mini-language that only mimicked some properties of Java.

That said, his way of working also seems to be very "hackerish", i.e. instead
of using "the normal ways", he hacks a model together that show some
properties that the conventional and more complex models have a hard time
showing. This is basically also how great hackers work, e.g. Paul Graham's Arc
(it's very unconventional and simplified - but great at showing the essence of
the hacker's ideas).

Anyway, great link!

------
dhuck
this is my favorite quote, from the "Be Silly" section: "If you want to
publish a paper in economic theory, there is a safe approach: make a
conceptually minor but mathematically difficult extension to some familiar
model. Because the basic assumptions of the model are already familiar, people
will not regard them as strange; because you have done something technically
difficult, you will be respected for your demonstration of firepower.
Unfortunately, you will not have added much to human knowledge."

be silly. do something completely different. the normal ideas that techcrunch
spits out day after day are played out, do something revolutionary.

------
andreyf
_What seems terribly hard for many economists to accept is that all our models
involve silly assumptions. Given what we know about cognitive psychology,
utility maximization is a ludicrous concept; equilibrium pretty foolish
outside of financial markets; perfect competition a howler for most
industries. The reason for making these assumptions is not that they are
reasonable but that they seem to help us produce models that are helpful
metaphors for things that we think happen in the real world._

I don't get it - how helpful are "metaphors for things we think happen in the
real world" if they aren't based in reality? Is that not like saying "let x be
an odd number divisible by 2 [...] hence, taxes should go up!". Or am I
misunderstanding the relationship between "proof" and "modeling".

Here's how it looks to me: economists believed that people are utility
optimizers, and form a lot of conclusions based on the idea. When it is found
untrue, economists modify what their theory is explaining (they say it's
explaining "market psychology" or some nonsense) so that their conclusions
still hold. It's not so obvious when the complicated workings of academics and
their institutions behave this day, but if a single individual ever behaved
like this, it would just seem stubborn.

~~~
mechanical_fish
_how helpful are "metaphors for things we think happen in the real world" if
they aren't based in reality?_

Metaphors -- in this context I'd call them "rules of thumb" -- are computable
by humans in real time. Reality generally isn't.

Technically, things don't fall down. When I hold a brick above your head and
then let go, you shouldn't just _assume_ that you have to dodge. You should
take note of all the massive objects in the vicinity and do a calculation
using the law of gravitation. You might also do some energetic calculations to
make sure that the brick won't just bounce harmlessly off of your head, or
come to rest on it like a falling feather.

Or, you know, you can avoid thinking at all and just allow the circuits in
your brain and spinal cord to get you out of the way fast so that you can live
to argue another day. Those circuits embody a relatively crude theory of
physics, and their design process didn't make use of a theory of physics at
all, but they work to keep you alive.

What Krugman is saying is that, while economists would love to develop the
economic equivalent of the law of gravitation (and some are even foolish
enough to believe that they have) their first priority is to develop some
rules of thumb that can tell us when to dodge, when to stand still, and when
to wear a hard hat. And that can be used to explain, in simple terms, where
the bump on our head came from. ("You stood under a metaphorical brick and
failed to dodge in the Keynesian manner.")

~~~
andreyf
Good points. However, the mathematical frameworks that economists use seem
somehow inappropriate for this - I wonder if economics will come to fruition
through a new mathematical system, as much of physics came to fruition through
the development of calculus.

Your reflex/calculation analogy makes me wonder if new neural network designs
ought to be tested against economic data...

------
carterschonwald
I like the bit where he keeps on pointing out how essential the style of
keeping the models simple and tractable was key to the vein of research.

this is a style that not enough folks actually focus on explicitly, at least
from my range of experience

~~~
13ren
It's difficult to create something simple. And then people say "but that's
simple". :|

High effort/low reward: not an attractive proposition. It doesn't attract many
folks.

You need a way to demonstrate that it wasn't obvious; and (I think) you need
to be a for-the-love-of-it kind of a guy: the _unreasonable man_ upon which
all progress depends.

------
fallentimes
I love reading stuff like this. I wish more super intelligent people did it.

------
robg
_All in all, though, I've been very lucky. A lot of that luck has to do with
the accidents that led me to stumble onto an intellectual style that has
served me extremely well._

------
pragmatic
R.I.P. Paul Krugman

[http://article.nationalreview.com/?q=NmZmMzlmZjU4NDVlMmFlZWR...](http://article.nationalreview.com/?q=NmZmMzlmZjU4NDVlMmFlZWRlZDM4YjZiYmRmYjc4NDQ=)

~~~
DanielBMarkham
Seems like you're posting an informed and reasonable argument from a political
site.

This argument has a contrary opinion to those expressed in this thread.

Burn the witch!

I wonder if I could make money selling pre-lit virtual torches for the angry
mob that is about to descend upon you?

Seriously -- I'd like to see this discussed in a separate article. Very
interesting stuff.

~~~
robg
That's not just any "political site". It's far right, especially now. Shoot,
Buckley's son just resigned his column there because he had the audacity to
support Obama. What would they have done to the father since, as a reasonable
conservative, I can't see him endorsing Palin?

The case against Krugman from those niches of the far right is almost entirely
political. That link is a good example of the genre.

This is better and back when NR had something worthwhile to say:

[http://article.nationalreview.com/?q=NmQ4MzY0NGVjODdmZmY2ZGQ...](http://article.nationalreview.com/?q=NmQ4MzY0NGVjODdmZmY2ZGQzMDAwZThmNTYyYzYxYjQ=)

~~~
DanielBMarkham
E-gad, it's the "let's be perfectly clear" meme. Wonder where you got that
one?

I don't mind you characterization of the site as far right wing. I'd simply
look at the facts, source if doubtful, and continue the discussion from there.
Same as if it were far left wing.

------
sdurkin
Oh, I love Prof. Krugman. Saw him at his press conference yesterday, and
hoping to congratulate him today.

------
vtnext
Krugman is obviously smart, as well as arrogant and a liberal shill. But
that's not the problem.

The issue is that he, and the economics establishment led by Helicopter Ben,
never met a rate cut they did not like. Cheap money and credit are the fix for
every problem. Today many recognize Greenspan held rates too low for too long.
At the time, Krugman opposed rate increases from those low levels. He and his
ilk fail to see any connection between destructive booms and the cheap credit
they promote.

~~~
startingup
vtnext, in all the excitement of his Nobel, his actual economic views (as
opposed to his politics, which I completely don't care about one way or
another) about events in the real world have been forgotten.

In fall of 2004, as Greenspan started raising interest rates in baby steps
(very belatedly - housing was already bubbling up), Krugman was very opposed
to those rate hikes. His analogy for the tech-telecom bust was with the post-
bubble doldrums in Japan - and it was no time to be risking a slide back by
rising rates.

In the event, directly as a result of that easy credit policy, we got the
mother of all bubbles in housing, which has almost taken the entire financial
system down with it. Krugman did not anticipate the bigger bubble that was
brewing even as he was advocating continuing 1% interest rates (well below the
rate of inflation even then!).

Economists like Nouriel Roubini, Steven Roach (then Chief Economist at Morgan
Stanley), eminent people like Paul Volcker (Fed Chairman between 79-87),
investors like Warren Buffet & Marc Faber all warned about the 2004-7 bubble
in housing several times, for many years. Krugman had a very public voice
during that entire time, but saw no problems with the Greenspan/Bernanke Fed.

It is worth remembering this real world record, as the world fetes his Nobel
prize.

~~~
gahahaha
Krugman in this op-ed from 2004 doesn't seem to be advocating lower interest
rates, but simply stating that they are probably coming, and that many people
are badly prepared for them.

[http://query.nytimes.com/gst/fullpage.html?res=9F05E6DD1E3BF...](http://query.nytimes.com/gst/fullpage.html?res=9F05E6DD1E3BF933A15757C0A9629C8B63)
"A number of analysts have accused Mr. Greenspan of fostering a debt bubble in
recent years, just as they accuse him of feeding the stock bubble during the
1990's. Just two months ago, Mr. Greenspan went out of his way to emphasize
the financial benefits of adjustable-rate, as opposed to fixed-rate,
mortgages. Let's hope that not too many families regarded that as useful
advice."

One reason why he might have argued for lower interest rates, is that the
employment growth during the "Bush Boom" was so dismal compared to earlier
expansionary periods. (See:
[http://krugman.blogs.nytimes.com/2008/08/26/about-that-
bush-...](http://krugman.blogs.nytimes.com/2008/08/26/about-that-bush-boom/))

------
andreyf
_The point is to realize that economic models are metaphors, not truth._

This seems like a big statement. What is the point of models, if they aren't
true? Metaphor is important in political rhetoric, but not necessarily in
science...

~~~
DLWormwood
> What is the point of models, if they aren't true?

Because they can make testable predictions or approximations for the truth.
This is not unique to Economics, even the "hard" sciences have to deal with
this problem. Before relativity was conceptualized, Newton's models for
gravity and inertia were considered "good enough" even though they were
observed to break down at the cosmic observational level. Even today, many
measurements have to account for uncertainty in unit size (even at the macro
scale!) and have to be accounted for when crunching numbers in serial
calculations. (Wikipedia's got several acceptable pages on several types of
uncertainty, especially measurement uncertainty.)

------
DanielBMarkham
Krugman, and the Politicization of the Prize (Editorial)

[http://www.realclearmarkets.com/articles/2008/10/krugman_and...](http://www.realclearmarkets.com/articles/2008/10/krugman_and_the_politicization.html)

~~~
olefoo
Give it up dude, nobody cares that you disagree with his politics.

He would not have been awarded the prize if his work wasn't important
regardless of his politics.

~~~
DanielBMarkham
It's not that nobody cares, it's that people are actively pissed off that I
questioned the selection.

Sorry, I'm not giving up being able to make a simple observation the group may
disagree with. I'm sick of the herd mentality, and you guys can vote me into
the gutter and it's not going to stop me.

I could care less about Krugman.

~~~
davidw
Another thing for you to keep in mind: the same group handed out prizes at
some point to Hayek and Friedman.

~~~
DanielBMarkham
I've been reading around some. As I was the first to admit, I am ignorant.
FWIW, glowing reviews are running about 70-30 with critical reviews of their
award. There's a nice glowing review over at Forbes
([http://www.forbes.com/opinions/2008/10/13/krugman-
economics-...](http://www.forbes.com/opinions/2008/10/13/krugman-economics-
nobel-oped-cx_as_1013subramanian.html))

Even then, the author ends with:

"But these days, even while disavowing overtly protectionist positions,
Krugman's columns do sometimes have a protectionist tenor. Not only purists,
but developing country policymakers, worry that Krugman is part of the
shifting intellectual climate in the United States that has become ambivalent
about keeping markets for goods and services open. Now that he also has the
imprimatur of the Nobel Committee, Paul Krugman has a special responsibility
to retain his cosmopolitan and internationalist credentials. At this time of
financial crisis, Krugman should be reminding us that shutting down markets
for trade helped transform the depression of the 1930s into the Great
Depression."

I'm open to discourse, just not impressed with the downmodding as a result of
going against the herd over here. I've found economics a subject of some
interest, but even with as much math as it takes, my _opinion_ is that it is
far from a hard science like physics. So pointing out that politics and
people's biases are involved shouldn't be such a freaking big deal, in my
opinion. And that goes with Hayek, Friedman, and Krugman. My comment holds for
all of them. That's the weird part about it.

~~~
davidw
> I'm open to discourse, just not impressed with the downmodding as a result
> of going against the herd over here.

That sort of thing pretty much invariably happens with economics or politics
on sites like this, whatever persuasion the 'herd' happens to be.

Which is why I think discussion of said topics should be ruthlessly hunted
down and driven away.

~~~
DanielBMarkham
Can I remind you that from where I sit, the title of the original post
translated into something like "Famous left-leaning columnist awarded prize by
committee slammed as being too political lately"?

So I _was_ hunting the articles down and driving them away. The problem is
that it didn't look like that for the majority.

If you don't want to see dissent and downmod it, then how can minority
opinions ever sway the majority that they are wrong? Sure, in this case I'm
probably smoking crack, but there's something really bad here.

~~~
olefoo
I've seen your handle in far too many threads lately, and for the most part I
just scroll past; because life is too short. In this particular case I chose
to comment because economics is an interest of mine as an entrepreneur. You do
not appear to be contributing to the conversation about ideas, you seem to be
mostly emoting and acting as though anything that does not conform to your
rather straitened ideological views is a personal attack on your ego. And
you've been doing this all day every day.

In this particular case it's clear that you did not RTFA since it's about
Krugman's workflow, and says relatively little about the substance of his work
and almost nothing about his politics other than that he regularly attempts to
think and write about topical policy debates.

It looks rather as though you read the the name Krugman and reacted
unthinkingly with an attack. That is not dissent, that is noise. If you want
to make noise may I suggest that the politics reddit is the right place for
you and that Hacker News is for people who want to focus on the ideas rather
than the emotions.

~~~
DanielBMarkham
Do you want a reply to this? I'm confused. If I'm trolling (which I'm trying
not to) then why comment in this manner? As a way of appealing to other
readers? I thought the thread system was set up in order to reply to
individual comments. Seems more like a rebuke.

Nicely done -- especially liked the part about emoting. The neat thing is that
it makes it impossible to reply in any fashion whatsoever. Which of course was
the point.

~~~
olefoo
I'm willing to grant you the benefit of the doubt when you say that you are
not intentionally trolling, but I respectfully submit that that is what you
come across as.

Starting highly charged political threads on topics that are only tangentially
related to the linked article does not contribute value to the discussion.

I've noticed for myself that one of the signs that I am spending too much time
in front of a computer is that I get into emotional arguments on internet
message boards or IRC. It's easy to forget that a level of emotional
involvement that would be normal and healthy IRL can make you seem like a
raving lunatic online.

Take that as you will. I am through with this thread.

 __PLONK __

------
cousin_it
Sadly, this didn't sound very intelligent to me. And I can't seem to
understand what significant things he did.

~~~
cousin_it
All right, I read up a bit. Downmodders, I fucking dare you, read this piece
by Krugman

<http://www.slate.com/id/9593>

and tell me again that he isn't a quack.

~~~
rms
<http://www.overcomingbias.com/2008/09/pundits-as-mole.html>

~~~
DanielBMarkham
I read that link four times.

Are you saying that Krugman was a spy who actually published and worked his
way up the right side of the political spectrum in order to make a stand for
his true left-leaning views? Or the other way around?

I found the "Pundits as Moles" post murky. I'm not so sure it helps in
overcoming bias as much as finding excuses for behavior we don't like. Pundits
could be moles, they could just sway with the partisan wind. Or they could
just be businesspeople looking at their daily ratings. A plug-and-play system
for determining motivations is _not_ something that will help you overcome
bias.

~~~
rms
I wasn't saying that Krugman was a spy for one side left or right -- he worked
his way up the academic spectrum of quantitative economics, in fact, all the
way to the very top. Now he gets to write about politics and literary
economics using the authority earned from his academic career. His current
motivation is getting Barack Obama elected and generally advocating higher
taxes and more government services.

I'm not reading into that "Pundits as Moles" post overly much -- I just
thought it funny that it seemed to apply to Paul Krugman.

------
mynameishere
Still depressed that this statist shill, who can't go two sentences without
contradicting human reason, won the "nobel" prize. For an example of a man who
actually improved human welfare, see the first physics recipient,

<http://en.wikipedia.org/wiki/Wilhelm_Conrad_R%C3%B6ntgen>

~~~
Prrometheus
He was awarded the prize for his academic work, not his shilling for the
Democratic Party.

~~~
DanielBMarkham
It's a prize. A prize in the field of economics, which is hardly physics.
Unless there is some empirical process for selection and award, it's just the
result of a committee's opinions.

If we can agree on that, certainly you can see that the door is open for the
members of the committee to be swayed by lots of things, including his
political work/views. To act otherwise is to try to turn respected scientists
into some sort of mechanistic non-humans. People are influenced by all sorts
of things, at the conscious and unconscious levels.

I have no idea what part of my statement is controversial. Yet it seems to
just drive some people nuts.

~~~
jcl
As far as I can tell from the Wikipedia page, there is no difference in the
selection processes for the physics and economics prizes... _All_ prizes are
just the result of a committee's (and nominators', and screeners') opinions.
In this respect, they are all equally valid.

For what it's worth, though, the committee members are selected by
Norwegian/Swedish institutions, which are perhaps less likely to be swayed by
political actions in the U.S.

