Professor Gunning offers us a well reason explanation for Marshall's
reversing the axes. Unfortunately, he offers no historical evidence to
support his hypothesis.
Marshall was a student of mathematics at Cambridge. Given his
interest in political economy, it is likely that he knew of William
Whewell's early mathematical economics papers (Whewell was still Master
of Trinity College at Cambridge while A. M. was a student there.)
Whewell, employing the King-Davenant "empirical" table (which he found
in Thomas Tooke's book *Thoughts and Details on High and Low Prices*),
developed rather sophisticated analyses of supply and demand. He
devised mathematical measures of demand elasticity (actually, since he
employed the King-Davenant "data", his was a measure of price
flexibility which is still an important tool in agricultural economics
where crop production has significant effects on crop prices). Using
his measure, he categorized goods according to their demand elasticity
(including demand curves which are perfectly inelastic, inelastic,
unitarily elastic, and elastic. He even laid out the Giffen Paradox!
though Giffen never did!).
It is clear that John Stuart Mill finally was able to employ
Whewell's demand elasticity concept to complete his analysis of
reciprocal demand in international trade.
Marshall certainly saw the advantages of employing the
King-Davenant "data table" in his own supply and demand analysis, given
the work of Tooke, Whewell, and Mill.
Jim Henderson
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>> Pat Gunning 02/03/11 12:47 PM >>>
If I understand Humberto's and Thomas's posts correctly, the simple
answer is "tradition" or "precedent." There is, I think, a more
penetrating answer.
It is that the goal of this framework has been to teach about scarcity.
Marshall used the demand and supply framework as an analogy, in my
interpretation. Having been trained in mathematics, he found more uses
than others. In his framework, what is scarce is quantities of objects
-- assumed quantities of homogeneous consumer goods and factors of
production. Scarcity refers in this scheme to a quantities in relation
to the valuations placed by demanders. Since quantities of things are
typically arranged by people who are subject to the law of gravity,
while values are abstract mental phenomena, the analogy seems easier to
communicate by putting quantity on the horizontal axis.
In other words, beginning economics students count quantities by lining
them up horizontally (as preschoolers who arrange their dolls and
soldiers on the table). They conceive of values abstractly. If you want
to communicate scarcity by means of a relationship between quantity and
values to students, it seems more efficient to do so in the way that has
become traditional.
Not all scarcity can be represented by this means. Scarcities of study
time, of capital, of NFL quarterbacks, of a work of art, of healthcare
or healthcare insurance, etc. do not seem worthwhile treating by means
of the demand supply framework. The framework is also ill-equipped to
show how the problem of scarcity is dealt with by individuals under
market economy conditions by means of a division of labor and how it is
dealt with by the isolated actor or central planner.
In the Walrasian, or GE system, these curves emerge as being
simultaneously determined, as Tony observed. They represent scarcity by
assuming fixed objective factors of production in relation to preference
functions in a multi-dimensional system. However, no teacher who I know
tries to communicate scarcity to her class in this way. Although I have
never had a class in this subject, I assume that the GE system is mostly
taught for other purposes.
On 2/2/2011 10:31 PM, Steve Horwitz wrote:
>
> Folks,
>
> It’s been a long time since I looked at this issue, so I’m going to
> rely on the wisdom of this wise crowd.
>
> What is the most accepted explanation for why we have the independent
> and dependent variables reversed in supply and demand graphs? It came
> up in class today and I gave “an” answer, but I admitted to my class
> that I wasn’t confident that I was correct. I also promised them I’d
> ask all of you.
>
> So what’s the consensus in HET on this issue?
>
> Thanks.
>
> Steve
>
> --
>
> Steven Horwitz
>
> Charles A. Dana Professor and Chair
>
> Department of Economics
>
> St. Lawrence University
>
> Canton, NY 13617
>
> Tel (315) 229 5731
>
> Fax (315) 229 5819
>
> Email [log in to unmask]
>
> Web: http://myslu.stlawu.edu/~shorwitz
>
--
Pat Gunning
Professor of Economics
Melbourne, Florida
http://www.nomadpress.com/gunning/welcome.htm
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