James.G. March, Charles A. Lave Introduction to Mod~ls in the Social Sciences,
an introduction to speculation
New York: HarperCollins, 1975. ·
10
2.1 INTRODUCTION
The best way to learn about model building is to do it. In this
cha~ter we invite you to specu:ate about human behavior. The
procedure we have ado]:ted is a familiar one. It is used by novelists
in d~veloping characters or events, by hi:;torians in interpreting
history, by children in :raining their parents, and by astronomers
in creating theories of the universe.
Despite such testimonials, our pro~edure is not the only
procedure for examining human ·:~ehavior. Intelligent people Cifi'er
on how to give meaning to observable phenomena. They differ even
more on a va:riety of special iss;les that we will happily ignore.
If W:! had sorne unique vision of the only way to approach s:~cial
science, we would be delighted tc present it. If we knew of some
majcr new sollltions to the ancier.t complications of the searclt for
interesting meanings, we would hurry to an-lounce them. Our intentions
are incomparably more moCest. Ve have found one common
appnach to interpreting human behavior both fruitful and erjoyable.
We hope you may find it similarly rewarding.
In this chapter we ask you to practice your skill at imagi:1.ing
speculations. In each section we start with an observation and
then speculate about processes tl:at might have produced the observed
fact. Tte examples are all taken fron the world of ordinary
experience: government, college life, friendship, and population
controL They even include one example drawn from the physical
world simp}y b demonstrate that the proce~s of speculation is fun
there too.
2.2 CONTACT AND FRIENDSHIP
Suppo)se we were interested in tl:e patterns of friendship among
college students. Why are some people friends and not others? We
rnigh: begin by asking all of the residents of single rooms along
a particular dcrmitory corridor to give us a list of their frie:1ds.
ThesE lists of friends are our initial data, the result we wish to
understand.
If we stare at the liste for a while to see what they mean,
we e~entua.lly notice a pattern in them: Fr'ends tend to live close
to each other; they tend to have ~djacent dormitory rooms. What
does this mean? What process cou~d have produced this pattern of
friendship?
contact it1ncl friend:
OLe feature of this book is that we will often ask you to stop
and do some thinking. We are serious.
STOP AND THINK. Devote a moment's time to thinktng
of a possible process that might produce th>S observed
result.
One possible process that might have led to this re>ult is the
following:
EG.ch spring the direetor of campus housing allows E.t~dents tc
indicate their dormitorv room preference for the folto·mng year;
groups of friends take advantage of this and ask to have eacl:
ober as roommates or -..o be put in adjacent rooms.
T~1is proces:ds a speculation about a prior world. !f the rea·t
world had once been like our model world, then the o_bserved fads
would have been a logical consequence. That is, this ::peculative
prior world would have produced our observed result, namely, tha:
friends tend to have adjacent rooms. Thus we have found a mode~
a process, that accounts for the facts. We do not stol? here. however;
We next ask: What other consequences does this model have.
What else does it imply~ It also implies that the studer.ts m each
dormitory friendship group must have kno~ each other. preVlous1y;
hence they must have attende.d th: univ~sity dunng th!
previous y~ar; hence there ·will be fewer fnendshlp clusters amon,.
freshmen. . . 1i
Is this further implication of our speculative pnor w.or
correct? To test it we first examine the frier.dship. patter~ 1n a
dormito::-y of juniors and seniors, and, as expected, ,,.e d1scover
groups of friends living nro:t to each other.
vr e also examine a dormitor:y that has only freilimen and
discover that there are as many grollps of friends clus:ered the~e
too, which is not an e=--pectad result (according to the model). Th:s
result would not have been predicted by our mo-de! unless the f:eshmen
knew each other prior 1:o college. Perhaps the freshnan_friendship
ch.:sters consist of students who knew each ot~r In h~gh
school and who asked for adjacent rooms. We look ':'t mformabcn
on the 'backgrounds of frei1men to see whether this IS true; but V'€