A word or two in defense of one-sector models.
1) Analytically 1-sector models are a special case of the general model, so
they are a legitimate place to start thinking about the properties of the
general model. Conjectures that are false in the one-sector model are
surely false in general, for example.
2) Empirically we depend a lot on national income data, which is most
easily interpretable in terms of a one-sector model. There is a tremendous
amount to be learned from comparative growth data at the aggregated level
(for example about the gross patterns of technical change, which links up
with the FRP.)
3) If the structure of production in different sectors (that is the
proportions in the input-output table) are not very different, the
one-sector model is a good approximation. To put this another way, you
could consider an economy with lots of different commodities, but if they
were all produced with the same input proportions, the economy would behave
like a 1-sector economy anyway.
4) Pedagogically it is almost impossible to start with a multi-sector
model, and most students aren't going to make the mathematical investment
required to grasp multi-sector models completely, so it is helpful for us
to have a very clear understanding of the 1-sector model.
Duncan
>Surely the basic objection to one sector models is that
>they do not deal with the capitalist mode of production, since
>that has to be a form of commodity production which presupposes
>a multiplicity of different physical products with money prices.
>
>At most they might be of some relevance to modeling things like
>cell growth in the presence of a single nutrient.
>
>Having one sector is quite different from forming monetary aggregates
>for the whole economy, since the latter makes no mention of physical
>quantities.
>Paul Cockshott
>
>wpc@cs.strath.ac.uk
>http://www.cs.strath.ac.uk/CS/Biog/wpc/index.html
Duncan K. Foley
Department of Economics
Barnard College
New York, NY 10027
(212)-854-3790
fax: (212)-854-8947
e-mail: dkf2@columbia.edu