**My Interpretation of the Thought of Karl Marx**

**Part Six: Enter the Mathematics**

(Several of the comments call for a response but I will
postpone that in order to get on with my exposition.)

There is, of course, vastly more to be said about Marx’s
views in volume 1, but I wish at this point to turn to the modern mathematical
interpretation of classical Political Economy which I mentioned at the very
beginning of this exposition. Unlike their modern descendants, the classical
economists made almost no use at all of formal mathematics. Marx had a go at
working out some numerical examples but mostly he botched it and it added very
little to his explanation of his theories. When the modern mathematical
re-interpreters of Ricardo and Marx undertook to translate their theories into
equations, they had to formalize a decision that Ricardo and the others had
made more or less without explicitly stating it.

In order to reduce the complexity of real economic activity
to equations, economists must in effect choose between supposing that there is
one dominant technique for the production of each distinct commodity and
supposing that there are an infinite number of techniques for the production of
each distinct commodity. To put this point as simply and formulaically as I
can, they have to decide whether they are going to use linear algebra or
calculus. The neoclassical assumption of an infinity of alternative ways of
combining inputs to produce an output lends itself to analysis using calculus
and the classical assumption of a single dominant technique of production for
each commodity finds its most natural expression in systems of linear
equations.

Linear algebra makes it possible to handle formally any
finite number of commodities, each one represented by a single vector of inputs
per unit of output. One can then manipulate what is called the unit input
matrix to derive a variety of powerful conclusions. Since I may have lost many
of you at this point, let me give a very simple example which will serve quite
adequately to illustrate what I want to say. All this is laid out precisely and
at length in my book, Understanding Marx.

Suppose we are talking about an elementary economy in which
there are only two commodities, corn and iron. (What we call corn does not grow
in England, of course, but the term “corn” was used by the English to mean “the
dominant grain of a region,” hence the great debate in the early 19^{th}
century in parliament as well as in the writings of the political economists
over the so-called “corn laws” regulating the importation of grain from abroad.) I have invented the following little
corn/iron economy to illustrate what I want to say. Since I am now doing
economics, there is no need for me to worry about the real-world relevance of
what I am saying.

Suppose it takes 100 units of labor, 2 units of seed corn,
and 10 units of iron to produce 300 units of corn. If we use the Greek letter l for
labor value or quantity of embodied labor with subscripts indicating whether we
are talking about the labor value of corn or the labor value of iron, and if we
recall, what is essential, that direct labor must be entered at par since it is
labor directly, not indirectly, contributed to the production of the output,
then we can write the labor value equation for the corn sector in the following
way:

100
+ 2l_{c}+
10l_{i }=
300l_{c}

In words, this equation says that when producing 300 units
of corn, the 100 units of labor directly applied in production and thus
embodied in the corn output, added to the amount of labor embodied in the two
units of corn used in production and the amount of labor embodied in the 10
units of iron used in production taken altogether equally amount of labor
embodied in the 300 units of corn that are the output of the production
process.

Using the letter p with appropriate subscripts to stand for
the prices of corn and iron, the letter w to stand for the wage paid for the
labor, and the Greek letter π to stand for the rate of profit, we can write the
corresponding price equations for this little corn/iron model. The price
equation in the corn industry looks like this:

(100w
+ 2p_{c}+ 10p_{i})(1 + π)
= 300p_{c }

If I choose the appropriate input quantities for the iron
sector and carry out a series of mathematical manipulations with which I shall
not trouble you, I can demonstrate that the prices of corn and iron are
proportional to their labor values, as Ricardo claimed, and also, what is
really quite interesting, that these prices and labor values are independent of
the wage and the profit rate, which vary inversely to one another, thereby also
demonstrating the class conflict between labor and capital. All very
impressive.

I spent a very great deal of time plowing through 10 or more
thick difficult mathematical economics texts in each of which the theories of
Ricardo and Marx were explored in excruciating detail. The big take away from
all these books was that both Ricardo and Marx had been, contrary to the
conventional wisdom, brilliant intuitive mathematical economists, much of whose
theoretical work was sustained by this sophisticated 20^{th} century
analysis.

But as I toiled away at my studies I noticed something
curious and eventually troubling. There were symbols in the equations in these
books for just about everything that Ricardo and Marx had talked about –
symbols for quantities of inputs, symbols for quantities of outputs, symbols
for prices of commodities, symbols for quantities of labor, and also the wages
of labor, symbols for profit rates earned by capitalists. But nowhere in the
equations could I find a symbol for Marx’s signature concept, labor power.
Since in Capital Marx had made the distinction between labor and labor power
the key to his solution to the central problem of the origin of profit, it
seemed to me that any modern mathematical rendering of his theories should have
somewhere a symbol for that central concept, but it was nowhere to be found. In
effect, the mathematical economists I was reading, all of whom were extremely sympathetic
to Marx’s theories, seemed to be saying that his story about the distinction
between labor and labor power was simply, in Pooh Bah’s immortal phrase from
the Mikado, merely “corroborative detail designed to lend an air of
verisimilitude to an otherwise bald and unconvincing narrative.”

At this point a thought occurred to me. (Now, this is a sad
tale but I feel compelled to tell it nonetheless.) Since there is no symbol for
labor power, the distinction between labor and labor power plays no role at all
in the formal analysis of Marx’s theories. To be sure, in the labor value
equations the labor inputs are valued at par and in the price equations the
price of labor has a letter, w, all its own, but the first is an assumption,
not a conclusion, and the second is simply a notational convention. Could one
write a set of equations that permitted us to calculate the iron value of labor
and corn, rather than the labor value of corn and iron?

Iron value!? What on earth would an iron value be? Nobody
ever talks about iron values or corn values but only about labor values. There
might in fact be a distinction between labor power and labor and no corresponding
distinction between corn power and corn or iron power and iron but if the
distinction between labor power and labor did not enter into the equations then
that would make no difference.

So I had a go at setting up some corn value and iron value
equations and seeing what I would get. The first question – quite important –
was whether one could always be sure in calculating iron values or corn values
that when the equations were solved those values would be positive. After all,
it would not make much sense to say that the amount of corn directly or
indirectly required for the production of a unit of iron was negative! Well, a
little mathematical manipulation (with some help from friends in the UMass
economics department) revealed that so long as there was any surplus of any
commodity anywhere in the system, all the corn values, or iron values, or labor
values, or x-values in the system would necessarily be positive.

One of Marx’s most striking claims, demonstrated to be
correct by the modern mathematical reinterpretations, was that the labor value
of the physical surplus is exactly equal to the surplus labor extracted in the
production process from the workers – a lovely mathematical demonstration of
the fact of exploitation. But a little more manipulation with the equations
demonstrated that this was also true for corn values or iron values. The corn
value of the physical surplus was exactly equal to the surplus corn value
extracted from the corn inputs in the system, and so forth.

In fact every single theoretical claim made by Marx in
Volume 1 of Capital (all the claims in volumes two and three, for that matter)
could be replicated using these nutty notions of corn value and iron value.

I was remarkably pleased with myself when I had reached
these conclusions for I thought that I was the first person in the entire
history of the discussion and commentary on the theories of Karl Marx to have
even thought of this, let alone to have demonstrated it mathematically. I told this story on my blog 10 years ago.
Let me close this episode in my exposition by reproducing what I wrote there:

In 1981, I published an essay entitled "A Critique and
Reinterpretation of Marx's Labor Theory of Value," in a journal called
PHILOSOPHY AND PUBLIC AFFAIRS. [I believe it is available
on-line.] In that essay, I proved an extremely important theorem that
shows that Marx was wrong to impute the exploitative capacity of capitalism to
the labor/labor power distinction. I was, I firmly believed, the first
person ever to realize the underlying logical flaw in Marx's argument, and to
demonstrate it mathematically. The proof was not much from a mathematical
point of view. Indeed, when I had first actually proved the theorem
several years earlier, I was ignorant of linear algebra, and had used nothing
but elementary algebra and some ingenious labeling moves. After the essay
appeared [since I made the mistake of publishing it in a philosophy journal,
almost no one read it who was capable of appreciating it], the brilliant,
mathematically extremely sophisticated Marxist John Roemer published a reply
and criticism in the journal in which, in passing, he pointed out that the same
theorem had been published two years earlier by Josep M. Vegara in a monograph
entitled ECONOMIA POLITICA Y MODELOS MULTISECTORIALES.

*Sic transit gloria mundi*

## 7 comments:

This grand "linear algebra" of which you speak is taught in high school in many countries.

As if the overwhelming majority of those students could have undertaken the analysis. The criterion of success in applied mathematics is empirical agreement. Whether the mathematics is elementary or advanced is immaterial.

"Since I am now doing economics, there is no need for me to worry about the real-world relevance of what I am saying." :)

Ahh, let me guess, Jerry, the quote is from Keynes---maybe in a letter to Wittgenstein or Russell.

I have no idea. As far as I know Professor Wolff devised it himself. And I got a laugh from it.

Why is the fact that you can get the same result from using corn value or iron value a problem for Marx's analysis? Plausibly there is no such thing as corn value or iron value, but there is such a thing as labor value, so an explanation in terms of labor value is preferable

It's a problem b.c if "surplus value" can be squeezed from any input, such as corn or iron, it means or at least implies that the supposedly distinctive or peculiar quality of the commodity labor-power, namely its capacity to "produce" or generate more value than it costs to "reproduce" the commodity itself, is not distinctive after all.

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