-
精品文档
?
美国大城
市的生与死
?
(THE DEATH AND LIFE OF GREAT
AMRICAN CITIES)
美国女作家简
.
雅各布斯
(Jane
Jacobs)
1 Introduction
(1)
This
book
is
and
attack
on
city
planning
and rebuilding. It is also, and
mostly,
an
attempt
to
introduce
new
principles
of
city
planning
and
rebuilding, different and even opposite
from
those
now
taught
in
everything
from
schools
of
architecture
and
planning
to
the
Sunday
supplements
and women’s magazi
nes. My
attack is
not based on quibbles about
rebuilding
methods or hairsplitting
about fashions
in design. It is an
attack, rather, on the
principles
and
aims
that
have
shaped
modern,
orthodox
city
planning
and
rebuilding.(2002.2.8)
(2) In setting forth different
principles,
I
shall
mainly
be
writing
about
common, ordinary
things: for instance,
what kinds of
city streets are safe and
what
kinds
are
not;
why
some
city
parks
are
marvelous
and
others
are
vice
traps
and
death
traps;
why
some
slums
stay
slums
and
other
slums
regenerate
themselves
even
against
financial
and
official
opposition;
what
makes
downtowns
shift
their
centers;
what,
if
anything,
is
a
city
neighborhood,
and
what
jobs,
if
any,
neighborhoods
in
great
cities
do.
In
short,
I
shall
be
writing
about
how
cities
work in real life, because this is
the
only
way
to
learn
what
principles
of
planning
and
what
practices
in
rebuilding
can
promote
social
and
economic
vitality
in
cities,
and
what
practices
and
principle
will
deaden
these
attributes.(2002.2.8)
(3)
There is a wistful myth that if only
we
had
enough
money
to
spend
—
the
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figure
is
usually
put
at
a
hundred
billion
dollars
—
we could wipe out
all
our
slums
in
ten
years,
reverse
decay
in
the
great,
dull,
gray
belts
that
were
yesterday’s and
day
-before-
yesterday’s
suburbs, anchor the wandering middle
class and its wandering tax money, and
perhaps
even
solve
the
traffice
problem.(2002.2.9)
(4)
But
look
what
we
have
built
with
the
first
several
billions:
Low-income
projects
that
become
worse
centers
of
delinquency,
vandalism
and
general
social hopelessness than the slums they
were
supposed
to
replace.
Middle-income
housing projects which
are
truly
marvels
of
dullness
and
regimentation
sealed
against
any
buoyancy
or
vitality
of
city
life.
Luxury
housing
projects
that
mitigate
their
inanity,
or
try
to,
with
a
vapid
vulgarity.
Cultural
centers
that
are
unable
to
support
a
good
bookstore.
Civic
centers
that
are
avoided
by
everyone
but
bums,
who
have
fewer
choices
of
loitering
place
than
others.
Commercial centers that are lackluster
imitations
of
standardized
suburban
chain-store shopping. Promenades that
go from no place to nowhere and have
no
promenaders.
.
Expressways
that
eviscerate
great
cities.
This
is
not
the
rebuilding of cities. This is the
sacking
of cities.(2000.2.9)
(5)
Under
the
surface,
these
accomplishments
prove
even
poorer
than their poor pretenses. They seldom
aid
the
city
areas
around
them,
as
in
theory
they
are
supposed
to.
These
amputated
areas
typically
develop
galloping gangrene.
To house people in
this
planned
fashion,
price
tags
are
fastened
on
the
population,
and
each
sorted-out
chunk
of
price-
tagged
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populace
lives
in
growing
suspicion
and
tension
against
the
surrounding
city.
When
two
or
more
such
hostile
islands
are
juxtaposed
the
result
is
called
“a
balanced
neighborhood.”
Monopolistic
shopping
centers
and
monumental
cultural
centers
cloak,
under the public
relations hoohaw, the
subtraction
of
commerce,
and
of
culture
too,
from
the
intimate
and
casual life of
cities.(2002.2.10)
(6)
That
such
wonders
may
be
accomplished, people who get marked
with the planners’ hex signs are pushed
about,
expropriated,
and
uprooted
much
as if they were the subjects of a
conquering power. Thousands of small
businesses
are
destroyed,
and
their
proprietors
ruined,
with
hardly
a
gesture
at
compensation.
Whole
communities
are
torn
apart
and
sown
to
the
winds,
with
a
reaping
of
cynicism,
resentment
and
despair
that
must be heard and seen to be believed.
A
group
of
clergymen
in
Chicago,
appalled
at
the
fruits
of
planned
city
rebuilding there, ask,
(7)
Could
job
have
been
thinking
of
Chicago when he wrote:
(8)
Here
are
men
that
alter
their
neighbor’s
landmark…shoulder
the
poor
aside,
conspire
to
oppress
the
friendless.
(9)
Reap they the field that is none of
theirs,
strip
they
the
vineyard
wrongfully seized from its owner…
(10) A cry goes up from the
city streets,
where wounded men lie
groaning…
(11) If so, he
was also thinking of New
York,
Philadelphia,
Boston,
Washington,
St.
Louis,
San
Francisco
and
a
number
of
other
places.
The
economic
rationale
of
current
city
rebuilding is a hoax. The economics of
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city
rebuilding
do
not
rest
soundly
on
reasoned
investment
of
public
tax
subsides,
as
urban
renewal
theory
proclaims,
but
also
on
vast,
involuntary
subsides
wrung
out
of
helpless
site victims. And the increased
tax
returns from such sites, accruing to
the
cities
as
a
result
of
this
“
investment,”
are
a
mirage,
a
pitiful
gesture
against
the
ever
increasing
sums
of
public
money
needed
to
combat
disintegration
and
instability
that
flow
from
the
cruelly
shaken-up
city.
The
means
to
planned
city
rebuilding
are
as
deplorable
as
the
end.(2002.2.12)
(12)Meantime,
all
the
art
and
science
of
city
planning
are
helpless
to
stem
decay
—
and
the
spiritlessness
that
precedes
decay
—
in ever more massive
swatches
of
cities.
Nor
can
this
decay
be
laid,
reassuringly,
to
lack
of
opportunity
to
apply
the
arts
of
planning.
It
seems
to
matter
little
whether
they
are
applied
or
not.
Consider
the Morningside Heights area
in
New
York
City.
According
to
planning
theory
it
should
not
be
in
trouble
at
all,
for
it
enjoys
a
great
aboudance
of
parkland,
campus,
playground
and
pleasant
ground
with
magnificent river views. It is a famous
educational
center
with
splendid
ins
titutions
—
Columbia
University,
Union
Theological
Seminary,
the
Juilliard
School
of
Music,
and
half
a
dozen others of eminent respectability.
It
is
the
beneficiary
of
good
hospitals
and
churches.
It
has
no
industries.
Its
streets
are
zoned
in
the
main
against
“incompatible
uses
“i
ntruding
into
the
preserves
for
solidly
constructed,
roomy,
middle-and
upper-class
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apartments.
Yet
by
the
early
1950’s
Morningside
Heights
was
becoming
a
slum
so swiftly, the surly kind of slum
in
which people fear to walk the streets,
that the situation posed a crisis for
the
institutions.
They
and
the
planning
arms
of
the
city
government
got
together, applied more
planning theory,
wiped
out
the
most
run-down
part
of
the
area
and
built
in
its
stead
a
middle-income
housing
project
complete
with
shopping
center,
and
a
public
housing project, all interspersed
with
air,
light,
sunshine
and
landscaping. This was hailed as a great
demonstration in city saving.
(13)After
that,
Morningside
Heights
went downhill even faster.
(14)Nor
is
this
an
unfair
or
irrelevant
example.
In
city
after
city,
precisely
the
wrong
areas,
in
the
light
of
planning
theory,
are
decaying.
Less
noticed, but equally significant, in
city
after city the wrong areas, in the
light
of
planning
theory,
are
refusing
to
decay.
(15)Cities
are
an
immense
laboratory
of
trial
and
error,
failure
and
success,
in
city building and city design. This is
the
laboratory
in
which
city
planning
should have been
learning and forming
and discipline (if
such it can be called)
have ignored the
study of success and
failure in real
life, have been incurious
about
the
reasons
for
unexpected
success,
and
are
guided
instead
by
principles
derived
from
the
behavior
and
appearance
of
towns,
suburbs,
tuberculosis
sanatoria,
fairs,
and
imaginary
dream
cities
—
from
anything
but
cities
themselves.(2002.2.13)
(16)
If
it
appears
that
the
rebuilt
portions
of
cities
and
the
endless
new
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developments
spreading
beyond
the
cities
are
the
reducing
city
and
countryside
alike
to
a
monotonous,
unnourishing
gruel, this is not strange,
It
all
comes,
first-,
second-
third-
or
fourth-
hand,
out
of
the
same
intellectual
dish
or
mush,
a
mush
in
which
the
qualities,
necessities,
advantages and behavior of great cities
have been behavior of other and more
inert types of settlements.
(17) There is nothing economically or
socially
inevitable
about
either
the
decay of old cities or the fresh-minted
decadence
of
the
new
unurban
urbanization. On the contrary no other
aspect of our economy and society has
been
more
purposefully
manipulated
for
a
full
quarter
of
a
century
to
achieve precisely what we are getting.
Extraordinary
governmental
financial
incentives have
been require to achieve
this
degree
of
monotony,
sterility
and
vulgarity.
Decades
of
preaching,
writing and
exhorting by experts have
gone
into
convincing
us
and
our
legislators that mush like this must be
good for us, as long as it comes bedded
with grass.
(18)Automobiles
are
often
conveniently
tagged
as
the
villains
responsible for the
ills of cities and the
disappointments
and
futilities
of
city
planning.
But
the
destructive
effect
s
of
automobiles
are
much
less
a
cause
than
a
symptom
of
our
incompetence
at
city
building.
Of
cause
planners,
including
the
highwaymen
with
fabulous sums of money
and enormous
power at their disposal,
are at a loss to
make
automobiles
and
cities
compatible
with one another. They do
not know what to do with automobiles
in cities because they do not know how
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to
plan
for
workable
and
vital
cities
anyhow
—
with or
without automobiles.
(19)The
simple
needs
of
automobiles
are
more
easily
understood
and
satisfied
than
the
complex
needs
of
cities,
and
a
growing
number
of
planners
and
designers
have
come
to
believe
that if they
can only solve the
problems
of
traffic,
they
will
thereby
have
solved
the
major
problem
of
cities. Cities have much more intricate
economic
and
social
concerns
than
automobile traffic. How
can you know
what to try with traffic
until you know
how
the
city
itself
works,
and
what
else it needs to do with its streets?
You
can’t.(2002.2.15)
(20)It may be that we have became so
feckless
as
people
that
we
no
longer
care
how
things
do
work,
but
only
what
kind
of
quick,
easy
outer
impression
they
give.
If
so,
there
is
little
hope for our cities or probably for
much else in our society. But I do not
think this is so.(2002.2.16)
(21)Specifically,
in
the
case
of
planning
for
cities,
it
is
clear
that
a
large
number
of
good
and
earnest
people
do
care
deeply
about
building
and renewing.
Despite some corruption,
and
considerable
greed
for
the
other
man’s
vineyard,
the
inte
ntions
going
into
the
messes
we
make
are,
on
the
whole,
exemplary.
Planners,
architects
of city design, and those they have led
along with them in their beliefs are
not
consciously
disdainful
of
the
importance
of
knowing
how
things
work. On the
contrary, they have gone
to
great
pains
to
learn
what
the
saints
and
sages
of
modern
orthodox
planning
have
said
about
how
cities
ought
to
work
and
what
ought
to
be
good
for
people
and
businesses
in
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them.
They
take
this
with
such
devotion
that
when
contradictory
reality
intrudes,
threatening
to
shatter
their
dearly
won
learning,
they
must
shrug reality
aside.(2002.2.17)
(22)Consider,
for
example,
the
orthodox planning reaction to a
district
called the North End in
Boston. This is
an old, low-rent area
merging into the
heavy industry of the
waterfront, and it
is officially
considered Boston’s worst
slum
and
civic
shame.
It
embodies
attributes which all enlightened people
know
are
evil
because
so
many
wise
men have said they are
evil. Not only
is
the
North
End
bumped
right
up
against
industry,
but
worse
still
it
has
all
kinds
of
working
places
and
commerce
mingled
in
the
greatest
complexity
with
its
residences.
It
has
the
highest
commerce
mingled
in
the
greatest
complexity with its residences.
It
has
the
highest
concentration
of
dwelling
nits,
on
the
land
that
is
used
for
dwelling
units,
of
any
part
of
Boston, and indeed one of
the highest
concentrations
to
be
found
in
any
American
city.
It
has
little
parkland.
Children play in the streets. Instead
of
super-blocks
or
even
decently
large
blocks,
it
has
very
small
blocks;
in
planning
parlance
it
is
“badly
cut
up
with
wasteful streets.” Its buildings are
old.
Everything
conceivable
is
presumably wrong with the North End.
In
orthodox
planning
terms,
it
is
a
three-dimensional
textbook
of
“
megalopolis”
in
the
last
stages
of
depravity.
The
North
End
is
thus
a
recurring
assignment
for
M.I.T.
and
Harvard
planning
and
architectural
students,
who
now
and
again
pursue,
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under
the
guidance
of
their
teachers,
the paper exercise of converting it
into
super-blocks
and
park
promenades,
wiping
away
its
nonconforming
uses,
transforming it to an ideal of order
and
gentility
so
simple
it
could
be
engraved on the head of a
pin.
(23)When
I
saw
the
North
End
again
in
1959,
I
was
amazed
at
the
change.
Dozens
and
dozens
of
buildings
had
been
rehabilitated.
Instead
of
mattresses
against
the
windows
there
were
Venetian
blinds
and
glimpses
of
fresh
paint.
Many
of
the
small,
converted houses now had only one or
two families in them instead of the old
crowded
three
or
four.
Some
of
the
families in the
tenements (as I learned
later,
visiting
inside)
had
uncrowded
themselves
by
throwing
two
older
apartments together,
and had equipped
these
with
bathrooms,
new
kitchens
and
the
like.
I
looked
down
a
narrow
alley, thinking to find at least here
the
old,
squalid
North
End,
but
no:
more
neatly
repointed brickwork, new blinds,
and a
burst of music as a door opened.
Indeed, this was the only city district
I
had
ever
seen
—
or
have
seen
to
this
day
—
in
which
the
sides
of
buildings
around
parking
lots
had
not
been
left
raw
and
amputated,
but
repaired
and
painted neatly as if they were intended
to
be
seen.
Mingled
all
among
the
buildings for living
were an incredible
number of splendid
food stores, as well
as
such
enterprises
as
upholstery
making,
metal
working,
carpentry,
food processing.
The streets were alive
with children
playing, people shopping,
people
strolling, people talking. Had it
not
been
a
cold
January
day,
there
would surely have been
people sitting.
(24)The
general
street
atmosphere
of
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buoyancy,
friendliness and good health
was
so
infectious
that
I
began
asking
directions of people
just for the fun of
getting in on some
talk. I had seen a lot
of
Boston
in
the
past
couple
of
days,
most
of
it
sorely
distressing,
and
this
struck me, with relief,
as the healthiest
place
in
the
city.
But
I
could
not
imagine
where
the
money
had
come
from
for
the
rehabilitation,
because
it
is
almost
impossible
today
to
get
any
appreciable
mortgage
money
in
districts of American cities that are
not
either
high-rent,
or
else
imitations
of
suburbs. To find out, I went into a bar
and
restaurant
(where
an
animated
conversation
about
fishing
was
in
progress) and called a
Boston planner I
know.
(25)“Why
in
the
world
are
you
down
i
n
the
North
End?”
he
said.
“Money?
Why, no money or work has gone into
the
North
End.
Nothing’s
going
on
down
there.
Eventually,
yes,
but
not
yet.
That’s a slum!”
(26)“It
doesn’t seem like a slum in the
city.
It
has
two
hundred
and
seventy-five
dwelling
units
to
the
net
acre! I hate to admit we
have anything
like that in Boston, but
it’s a fact.”
(27)“Do you
have any other figures on
it?” I asked.
(28)“Yes,
funny
thing.
It
has
among
the
lowest
delinquency,
disease
and
infant mortality rates
in the city. It also
has
the
lowest
ratio
of
rent
to
income
in
the
city.
Boy,
are
those
people
getting bargains.
Let’s see . . . the child
population is
just about average for the
city, on the
nose. The death rate is low,
8.8
per
thousand,
against
the
average
city
rate
of
TB
death
rate
is
very low, less than 1 per ten thousand,
can’t
understand
it,
it’
slower
even
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than
Brookline’s.
In
the
old
days
the
North
End
used
to
be
the
city’s
worst
spot
for
tuberculosis,
but
all
that
has
changed.
Well
they
must
be
strong
people. Of course
it’s a terrible slum.”
(29)“You should have more slums like
this,”
I
said.“
Don’t
tell
me
there
are
plans
to wipe this out. You ought to be
down
here learning as much as you can
from
it.”
(30)“I know how you
feel,” he said.“ I
often
go
down
there
myself
just
to
walk
around
the
streets
and
feel
that
wonderful,
cheerful
street
life.
Say,
what
you
ought
to
do,
you
ought
to
come back and go down in
the summer
if
you
think
it’s
fun
now.
You
‘d
be
crazy
about
it
in
summer.
But
of
course we
have to rebuild it eventually.
We’ve
got
to
get
those
people
off
the
streets.” (2002.2.18)
(31)Here
was
a
curious
thing
.My
friend’s
instincts
told
him
the
North
End
was
a
good
place,
and
his
social
statistics
confirmed
it.
But
everything
he learned as a
physical planner about
what
is
good
for
people
and
food
for
city
neighborhoods,
everything
that
made
him
an
expert,
told
him
the
North End
had to be a bad place.
(32)The leading Boston savings banker,
“a
man
’way
up
there
in
the
power
structure
,”
to
whom
my
friend
referred
me
for
my
inquiry
about
the
money,
confirmed
what
I
learned,
in
the
meantime,
from
people
in
the
North End . The money
had not come
now
knows
enough
about
planning
to
know
a slum as well as the planners do.
“No
sense
in
lending
money
into
the
North
End,”
the
banker
said.
“It’s
a
slum!
It’s still getting some immigrants!
Furthermore, back in the Depression it
had
a
very
large
number
of
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foreclosures; bad record.” (I had heard
about
this
too,
in
the
meantime,
and
how
families
had
worked
and
pooled
their
resources
to
buy
back
some
of
those foreclosed buildings.)
(33)The
largest
mortgage
loans
that
had
been fed into this district of some
15,000
people
in
the
quarter-century
since
the
Great
Depression
were
for
$$3,
000, the
banker told me, “and very,
very
few
of
those.”
The
rehabilitation
work
had
been
almost
entirely
financed
by
business
and
housing
earnings
within
the
district,
plowed
back
in,
and
by
skilled
work
bartered
among
residents
and
relatives
of
residents.
(34)By
this
time
I
knew
that
this
inability
to
borrow
for
improvement
was
a
galling
worry
to
North
Enders,
and
that
furthermore
some
North
Enders
were
worried
because
it
seemed
impossible to get new building
in the
area except at the price of seeing
themselves and their community wiped
out
in
the
fashion
of
the
students’
dreams
of
a
city
Eden,
a
fate
which
they knew was not
academic because it
had
already
smashed
completely
a
socially
similar
—
although
physically
more
spacious
—
nearby
district
called
the
West
End.
They
were
worried
because
they
were
aware
also
that
patch
and
fix
with
nothing
else
could
not
do
forever.
“Any
chance
of
loans
for
new
construction
in
the.
North
End?”
I asked the banker.
(35)“No,
absolutely
not!”
he
said,
sounding
impatient
at
my
denseness.
“That’s a slum!”
(36)Bankers,
like
planners,
have
theories about cities on which they
act.
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They
have
gotten
their
theories
from
the
same
intellectual
sources
as
the
planners.
Bankers
and
government
administrative
officials
who
guarantee
mortgages
do
not
invent
planning
theories
nor,
surprisingly,
even
economic
doctrine
about
cities.
They
are
enlightened
nowadays,
and
they
pick
up
their
ideas
from
idealists,
major new ideas for considerably more
than a generation, theoretical
planners,
financers
and
bureaucrats
are
all
just
about
even today.
(37)And to put it bluntly, they are all
in
the
same
stage
of
elaborately
learned
superstition
as
medical
science
was
early
in
the
last
century,
when
physicians
put
their
faith
in
bloodletting
,
to
draw
out
the
evil
humors
which
were
believed
to
cause
disease.
With
bloodletting,
it
took
years
of
learning
to
know
precisely
which
veins,
by
what
rituals,
were
to
be
opened
for
what
symptoms.
A
superstructure
of
technical
complication
was
erected
in
such
deadpan
detail
that
the
literature
still
sounds
almost
plausible.
However,
because
people,
even
when
they
are
thoroughly
enmeshed
in
descriptions
of
reality
which
are
at
variance
with
reality,
are
still
seldom
devoid
of
the
powers of observation and independent
thought,
the
science
of
bloodletting,
over
most
of
its
long
sway,
appears
usually
to
have
been
tempered
with
a
certain amount of common sense. Or it
was
tempered
until
it
reached
its
highest
peaks
of
technique
in,
of
all
places,
the
young
United
States.
Bloodletting went
wild here.
It had an
enormously influential proponent in Dr.
Benjamin
Rush,
still
revered
as
the
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greatest
statesman-physician
of
our
revolutionary
and
federal
periods,
and
a genius of medical
administration. Dr.
Rush
Got
Things
Done.
Among
the
things
he got done, some of them good
and
useful,
were
to
develop,
practice,
teach
and
spread
the
custom
of
bloodletting
in
cases
where
prudence
or
mercy
had
heretofore
restrained
its
use.
He
and
his
students
drained
the
blood
of
very
young
children,
of
consumptives,
of
the
greatly
aged,
of
almost
anyone
unfortunate
enough
to
be sick in his realms of
influence. His
extreme
practices
aroused
the
alarm
and
horror
of
European
bloodletting
physicians. And
yet as
late as 1851, a
committee
appointed
by
the
State
Legislature
of
New
York
solemnly
defended
the
thoroughgoing
use
of
bloodletting.
It
scathingly
ridiculed
and
censured
a
physician,
William
Turner, who had the temerity to write a
pamphlet
criticizing
Dr.
Rush’s
doctrines
and
calling
“the
prac
tice
of
taking
blood
in
diseases
contrary
to
common
sense,
to
general
experience,
to
enlightened
reason
and
to
the
manifest
laws
of
the
divine
Providence.”
Sick
people
needed
fortifying, not draining, said Dr.
Turner,
and he was squelched
(38)Medical
analogies,
applied
to
social
organisms,
are
apt
to
be
farfetched,
and
there
is
no
point
in
mistaking
mammalian
chemistry
for
what occurs in a city. But analogies as
to what goes on in the brains of
earnest
and
learned
men,
dealing
with
complex
phenomena
they
do
not
understand at all and trying to make do
with
a
pseudoscience,
do
have
point.
At in
the pseudoscience of bloodletting,
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just
so
in
the
pseudoscience
of
city
rebuilding
and
planning,
years
of
learning
and
a
plethora
of
subtle
and
complicated
dogma
have
arisen
on
a
foundation
of
nonsense.
The
tools
of
technique have steadily been perfected.
Naturally,
in
time,
forceful
and
able
men,
admired
administrators,
having
swallowed
the
initial
fallacies
and
having been provisioned with tools and
with public confidence or mercy might
previously
have
forbade.
Bloodletting
could heal only by accident or insofar
as
it
broke
the
rules,
until
the
time
when it
was abandoned in favor of the
hard,
complex business of assembling,
using
and
testing,
bit
by
bit,
true
descriptions of reality drawn not from
how it ought to be, but from how it is.
The
pseudoscience
of
city
planning
and
its
companion,
the
art
of
city
design,
have
not
yet
broken
with
the
specious
comfort
of
wishes,
familiar
superstitions,
oversimplifications,
and
symbols,
and
have
not
yet
embarked
upon the adventure of probing the real
world.
(39)So
in
this
book
we
shall
start,
if
only in a small way,
adventuring in the
real
world,
ourselves.
The
way
to
get
at
what
goes
on
in
the
seemingly
mysterious
and
perverse
behavior
of
cities
is,
I
think,
to
look
closely,
and
with as little previous expectation as
is
possible,
at
the
most
ordinary
scenes
and
events,
and
attempt
to
see
what
they mean and whether
any threads of
principle
emerge
among
them.
This
is
what I try to do in the first part of
this
book.
(40)One
principle
emerges
so
ubiquitously, and in so many and such
complex different forms, that I turn my
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attention
to
its
nature
in
the
second
part
of
this
book,
a
part
which
becomes
the
heart
of
my
argument.
This ubiquitous
principle is the need of
cities
for
a
most
intricate
and
close-grained
diversity
of
uses
that
give
each
other
constant
mutual
support,
both
economically
and
socially.
The
components
of
this
diversity
can
differ
enormously,
but
they
must
supplement
each
other
in
certain
concrete ways.
(41)I think
that unsuccessful city areas
are
areas
which
lack
this
kind
of
intricate
mutual
support,
and
that
the
science of city planning
and the are of
city
design,
in
real
life
for
real
cities,
must
become
the
science
and
art
of
catalyzing
and
nourishing
these
close-grained
working
relationships.
I
think,
from
the
evidence
I
can
find,
that
there
are
four
primary
conditions
required
for
generating
useful
great
city
diversity,
and
that
by
deliberately
inducing
these
four
conditions,
planning
can
induce
city
vitality
(something
that
the
plans
of
planners
alone,
and
the
designs
of
designers
alone, can never
achieve). While Part I
Is principally
about the social behavior
of people in
cities, and is necessary for
understanding
what
follows,
Part
II
is
principally
about
the
economic
behavior
of
cities
and
is
the
most
important part of this book.
(42)Cities
are
fantastically
dynamic
places, and this is striking true of
their
successful
parts,
which
offer
a
fertile
ground
for
the
plans
of
thousands
of
people. In the third part of this book,
I
examine
some
aspects
of
decay
and
regeneration, in the
light of how cities
are
used,
and
how
they
and
their
people behave, in real life.