Marie-Ésprit Léon Walras - 經濟

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作者: fizeau (.) 看板: Math
標題: [名人] Marie-Ésprit Léon Walras
時間: Tue Apr 29 22:09:02 2008

http://cepa.newschool.edu/het/profiles/walras.htm
The French economist Léon Walras (pronounced "Valrasse") has been hailed by
Joseph Schumpeter as "the greatest of all economists" (Schumpeter, 1954:
p.827). Walras was one of the three leaders of the Marginalist Revolution,
even though his greatest work, Elements of Pure Economics, was published in
1874, three years after those of William Stanley Jevons and Carl Menger.

Nonetheless, alone among the three revolutionaries, Léon Walras set forth
the new "marginalist" or "Neoclassical" theory in a formal general
equilibrium setting. Thus, he endowed it with the multi-market
considerations Jevons had largely avoided and the mathematical precision
Menger had eschewed. Léon Walras is widely and rightfully regarded as the
father of general equilibrium theory.

From any biography, the principal elements of Walras's life can be told. He
was the son of the French proto-marginalist economist and schoolteacher,
Auguste Walras. After spending a Bohemian youth in Paris as a novelist and
art critic, Léon Walras soon followed his father's footsteps on almost every
count: he adopted his father's socialist policy positions on taxation and
land reform (in fact, he was a proponent of outright land nationalization) as
well as his main ideas on economic theory (subjectivist theory of value, the
mathematization of economics). After spending some unfruitful years in the
cooperatives movement, Walras was appointed to the Academy of Lausanne in
1870. It was there that he wrote and published the first edition of his
magnum opus, the Elements of Pure Economics (1874).

Léon Walras's Elements should be familiar to every modern economist, as it
encompasses much of what is available to us in modern general equilibrium
theory. Walras set out his Elements in progressive stages of complexity and
generality. Its eight parts can be briefly summarized:

(1) Walras provides his definition of the scope of economics, subjective
value theory and the mathematical method;

(2) discusses two-commodity pure exchange where demand and supply are derived
from utility-maximization; his "auctioneer" and the tatonnement process of
stability is introduced here.

(3) introduces multi-market pure exchange; counts "equations and unknowns" to
find existence; considers multi-market tatonnement with an auctioneer.

(4) incorporates production (in early editions, with fixed technology; in
later editions, with flexible technology and thus marginal productivity
theory) with a no-profit entrepreneur; shows how the demand for factors is
derived as an indirect demand for goods (see the "Walras-Cassel" model).

(5) introduces his theory of capital; includes capitalization of future
earnings and presents a theory of saving and credit;

(6) introduces his encaisse desirée theory of money; sees money as providing
future services and thus "desired" in a general choice problem;

(7) considers the continuous market and a growing economy.

(8) provides reflections on imperfect competition and monopoly.

In the aftermath of the Elements, Walras tried to build up a correspondence
with virtually every important economist of the time, from America to Russia,
in an effort to popularize his new theory. He found sympathizers and
followers among several technically-gifted young Italians (e.g. Barone and
Pareto) and Americans (e.g. Moore and Fisher). However, for the most part, he
was largely ignored or dismissed by contemporary economists and
mathematicians.

In 1893, Walras was succeeded in his chair by his young disciple, Vilfredo
Pareto. The two men formed the core (and some argue the full extent) of what
became known as the Lausanne School". While they agreed on most theoretical
matters, the details of the subsequent research program were dictated more by
Pareto's interests than Walras's original concerns.

Walras had envisaged his 1874 Elements as part of a larger work. However, by
the 1890s, Walras's mental capacities had begun to fail and it became
doubtful that he would be able to complete this grand oeuvre in the manner he
had originally intended Walras hastily compiled two volumes, Studies in
Social Economics (1896) and the Studies in Applied Economics (1898).

Although little more than compilations of previously published articles, he
still considered these books complementary to the Elements. Tellingly, the
1874 Elements are subtitled "theory of social wealth", while his 1896 book is
subtitled "theory of the division of social wealth" and his 1898 book "theory
of the production of social wealth." He regarded all three volumes as
integral, indivisible and essential pillars for his general economic theory.

Unfortunately, most economists dismissed these last two volumes as "light"
stuff or, worse, a mere platform for socialist politics. Today, as then, the
Elements alone is regarded as his Walras's only "true" contribution.

However, some economists continue to believe that, because his other two
volumes were not taken into account, modern Neo-Walrasian G.E. theory has not
adhered to Walras's original vision, either in general purpose or in detail.

Modern economists have also dismissed Walras's attempt, in a later (1896)
edition of the Elements, to take credit for the discovery of the marginal
productivity theory of distribution (and denouncing Wicksteed's claim to
priority), not only as lacking any basis in truth but even as mean-spirited.

It is widely acknowledged that Walras learnt this theorem from Enrico
Barone. (although, in a striking coincidence, Walras had been handed the
theorem on a piece of paper from the Lausanne mathematician, Hermann Amstein,
in 1877, but had not understood the mathematics well enough the make heads or
tails out of it!)

The last decade of Walras's life was spent in frustrated loneliness, bitter
at the neglect of his work, incapacitated by senility and mental illness. He
died in 1910.

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