That Mill provided purely verbal instructions for how to build a  
Marshallian Cross: agreed. That Mill's Stiglerian "original discovery"  
was on a par with those of Cournot, Rau, Dupuit, Mangoldt, and Jenkin  
who actually drew the Cross diagram: disagree. That Marshall's  
inspiration came from Mill and not from the others too: disagree.

I shall say no more on this matter.

On Feb 28, 2014, at 6:12 PM, James C.W. Ahiakpor wrote:

> Thomas Humphrey wrote:
>> Mill's purely verbal discussion pertains not to the determination  
>> of the price of an individual good, but rather to the determination  
>> of the international terms of trade between a country's exports and  
>> its imports.
> This is truly remarkable.  If Tom is unaware of Mill's explanation  
> of (domestic) market prices by supply and demand, here is the text:
>
> "Whether the demand and supply are equalized by an increased demand,  
> the result of cheapness, or by withdrawing a part of the supply,  
> equalized they are in either case...
>    ... the proper mathematical analogy is that of an /equation/.  
> Demand and supply, the quantity demanded and the quantity supplied,  
> will be made equal. If unequal at any moment, competition equalizes  
> them, and the manner in which this is done is by an adjustment of  
> the value [price]. If the demand increases, the value [price] rises;  
> if the demand diminishes, the value [price] falls: again, if the  
> supply falls off, the value [price] rises; and falls if the supply  
> is increased. The rise or fall continues until the demand and supply  
> are again equal to one another. (Mill /Works/, 3: 467–8; italics  
> original)
>
> Tom also wrote:
>
>> Contrary to James, I doubt Mill's relevance in this connection. For  
>> Mill never drew the Marshallian cross diagram, although he did  
>> discuss (in words) the concept of supply and demand functions. He  
>> can hardly be said to be a precursor -- or grandfather/inventor --  
>> of a diagram he never drew. To jump from a purely verbal treatment  
>> of supply and demand to a geometrical, diagrammatic demonstration  
>> takes a huge leap of imagination.
> Now, nowhere did I claim that Mill drew a diagram.  What I wrote is  
> the following:
>
> "As for Marshall's supply and demand diagram, it follows closely  
> after J.S. Mill's restatement of the classical theory of value --  
> explanation of market prices.  And Mill was reformulating the theory  
> of value from Smith, Malthus, and partly Ricardo.  I wouldn't want  
> to follow Tom's treatment of Marshall's recognition for that diagram  
> under Stigler's Law."
>
> A little more careful reading could save a lot of wasteful debate,  
> "me thinks."  Marshall trained first as a mathematician before  
> turning to economics.  He thus was putting into pictures (diagram)  
> what he'd learned from J.S. Mill.  That was my point.
>
> James Ahiakpor
>
> -- 
> James C.W. Ahiakpor, Ph.D.
> Professor
> Department of Economics
> California State University, East Bay
> Hayward, CA 94542
>
> (510) 885-3137 Work
> (510) 885-7175 Fax (Not Private)