Re: more squiggly lines

[Alan G Isaac <aisaac@xxxxxxxxxxxx>]

On Sat, 27 Jul 2002 18:24:41 -0400 Gunnar Tomasson <gunnar.tomasson@xxxxxxxxxxx> wrote:
> As it happens, the Circular Flow view is to economics what Newton's
> Gravitational Equations (see below) are to solar system mechanics.  For,
> contrary to the conventional construction thereof, Newton emphasized in his
> introductory remarks in Part III of Principia (Definition VIII) that his
> Equations were NOT to be construed as EXPLANATORY with respect to the
> factors involved in solar system orbital mechanics:

> "I likewise call attractions and impulses, in the same sense, accelerative
> and motive; and use the words attraction, impulse, or propensity of any sort
> towards a centre, promiscously, and indifferently, one for another;
> considering those forces NOT physically, but mathematically: wherefore the
> reader is NOT to imagine that by those words I anywhere take upon me to
> define the kind, or the manner of any action, the causes or the physical
> reason thereof, or that I attribute forces, in a true and physical sense, to
> certain centres (which are only mathematical points); when at any time I
> happen to speak of centres as attracting, or as endued with attractive
> powers."


A more egregious misreading of this simple quote is hard to imagine,
especially given the dead-give-away phrase "in a true and physical
sense".  How much can we twist the observation that it is convenient
to represent the physical attraction between objects as an attraction
between their centers, which are of course only mathematical points?
I guess you are out to show us ...

And of course it must be pure accident that Newton speaks of "forces"
rather than "x" (or "smells" for that matter)??  Of course not:
Newton's very vocabulary betrays his explanatory motivation and
intent.  He comments explicitly: "And to us it is enough that gravity
does really exist, and act according to the laws which we have
explained, and abundantly serves to account for all the motions of the
celestial bodies, and of our sea." He *must* explain with the *force*
of gravity, and yet he has been forced to discard his contemporaries
understanding of gravitational attraction.  What to do?  What to do?
How about avoiding controversy by refusing to speculate on its nature?
(Publically of course; while privately speculating that god hirself was
at work.)

And of course the truth of the matter remains that Newtonian physics
is fully adequate to quite a bit of explanatory activity, even in
contemporary engineering, and that the attraction between objects
remains quite a useful *explanatory* apparatus, even if it can be
subjected to redescription.  Just because an explanation cannot reach
into the mind of god (which, I take it, is the best conceptualization
of your "definitive explanatory model") does not mean it is not an
explanation.

If we are to turn to Newton for methodological guidance and
metaphysics, are we are to be led into the realm of vitalism and
theology, including biblical prophecy?  Or are we to stop with the
crude inductionist proposals he offers for "experimental philosophy"?
Such appeals to authority are not very interesting.  They are simply
opportunistic rhetoric unless they are less selective, at which point
they become simply absurd.

Cheers,
Alan Isaac