[OPE-L] Teaching Tautologies : a response to David L

From: Gerald_A_Levy@MSN.COM
Date: Sat Mar 12 2005 - 19:01:55 EST

I also attended the EEA session last week chaired by David L.
Besides David,  Ingrid Rima and Mary C. Cleveland presented
papers.  Cleveland is a modern-day disciple of Henry George
and there were a number of  other people at the session who
also admired George.  In a throw-back to the period before
George, she presented a *corn model* in her paper on "Inequality
and Macroeconomic Instability".   When Rima emphasized in
her presentation that "money matters", I thought there would be
a discussion of the failings of the moneyless corn model but no
one picked-up on that issue.  Interestingly, David suggested that
a Marxian response to the writings of Henry George could be
found in Blake's _An American Looks at Karl Marx_.  Yet,
when I reexamined my copy later I couldn't find a whole lot in
Blake on George.

Now I turn to David's paper and the main concern of this post.

You might recall that David told us about his paper presenting a
"new critical" macro proposal some time ago:

> I call it the "Dobb Effect," linking Maurice Dobb's 1929 article, "A
> Skeptical View of the Theory of Wages," to macro policy issues (which he
> did not do).  Macro policy moves a) influence the *balance of class
> forces* (a  term that does *not* appear in the paper!); and b) flatten
> out the AS curve  (even in the presence of full price flexibility and
> rational expectations).

The context of David's paper is that it addressed a point related to
the _teaching_ of  (undergraduate) intermediate macroeconomics.
This is an important point to remember -- which I will return to
later in the post.

Employing the well-known graphics of an aggregate supply and aggregate
demand curve graph, David sought to demonstrate the consequences of
increasing aggregate demand (under a condition I am about to mention)
on the working class.

In listening to David's presentation, I realized that the point of his
formalism could be made even more simply without equations and

Start by assuming a fixed money wage rate.

Then, suppose that aggregate demand grows.

Consequence:  the working class is hurt.

I can hear you say:  could you run that by me one time again?

Sure.  I'll change the words a little.

a) Start (as before) by assuming that there is  a fixed money wage rate.

b) Then, suppose that there is a general rise in prices (inflation) caused
    by an increase in aggregate demand.

c)  Real wages for workers decline.

From the foregoing, David was able to further hypothesize (in my view,
quite reasonably) that under these conditions workers will often
attempt to maintain their real wage by taking a 2nd and/or possibly
a 3rd job.

What became obvious to me is that -- despite the elegant graphics
and formal equations -- c) was simply, under the conditions of a) and b),
a *tautology*.    I thought ...  well ... yeah ... of course ... if money
are fixed and there is inflation then real wages will decline *by
So, in the discussion that ensued, I called this to the attn. of  DL and
him why his proposition wasn't a tautology.

I don't recall his exact response, but it seemed to me to make
two points:

i) it was more than a _simple_ tautology in the sense that it
embodied particular historical and conceptual understandings about
the wage.  For example, the proposition that the money wage
rate was, especially in the short-run, fixed was based on the
Keynesian idea that money wages are "sticky."

ii) it _was_ a tautology but tautologies have legitimate uses in
political economy.

I'll grant him i).



I'm wondering if we could have a discussion on  *what, if any, are
the legitimate uses of tautologies in political economy?*

Can any of you, including David, explain _when_ it is appropriate
to base theoretical understandings on tautologies and _when_ it is


Now, I return to the context that this issue came up for David
in  *teaching* intermediate macroeconomics.

I'll grant that it is a legitimate and important point to make in the
classroom in order to explain the meaning of  inflation for workers
under varying conditions.  I'll even grant that David's paper describes
what I take to be a *historical pattern*.  I think it's especially true
during high inflationary periods -- e.g. his graphs could be used
to suggest why in the US in the 1970's, more and more working
class families had two income earners rather than one.  (Of course
it's not the whole explanation.  I'm sure DL would agree.  But, it
is a large part of the story.)

What really confuses  me, though, is that David said that when
he presented his graphs in the classroom to make this point,
his students really *appreciated* the graphs.  This made me think:
what kind of students does DL teach?

I can tell you that my students *strongly* prefer that I keep
the graphs presented in the classroom to a minimum.  Indeed,
when graphs are drawn -- no matter how well explained by the
instructor -- there are always some students whose eyes
glaze over.  They can think logically, no doubt.  But they are
not used to and don't generally like graphs.

Well, of course, you have to have _some_ graphs when teaching
economics, but were equations and graphs really needed for
DL to forcefully make the point in the classroom that he wanted
to make?  I don't see why.  After all,  any relationship that can
be expressed graphically can also be expressed orally and verbally.
And, in this case, I think that his point could have been made
easier *without* graphs.

So,  it makes me wonder:  is there something wrong with his
students or mine; is his teaching too graph-intensive or is my teaching
not graph-intensive enough?



Are elegant graphics really needed to explain tautologies?

What other tautologies are *taught* in the economics classroom?

What are examples of legitimate tautologies advanced by Marx
in his presentation in _Capital_?

What are examples of legitimate tautologies advanced by Marxians
in the presentation of political economy?

Do we all teach what a tautology is in the classroom?  What do we
say?  In particular, what do we tell students about the legitimate
(?)  *uses of* tautologies in economic theory?

In solidarity, Jerry

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