It looks to me as if part of the discussion between Alan
and Fred is based on the contrast between what Mirowski calls
field and a substance interpretation of value, with
Alan prefering a substance theory and Fred a field theory.
Alans objections to value 'appearing from nowhere', when
means of production are revalued upwards, is a substance
based objection, which is meaningless under a field theory.
But one can overdo the field theory. The potential of changes in the
value of means of production to alter the value of the product is
limited. Consider the case of steel entering into the production of a
ship whose production takes 2 years. It is socially necessary that the
steel used in the keel is purchased at least two years before the ship
goe into service. Any fall in the price of steel during those two years
is irrelevant since it can not through competition affect the ships
offered for sale on the market for another two years. If steel has fallen
in price by 20 0uring the last two years, then Yarrows will take this
into account in any tenders that they put to construct new ships, but it
will not affect the value of the ships currently being made.
If, on the other hand, we are dealing with goods whose production time is
very short compared to the turnover time of stocks of raw materials -
bread for example - then the situation is different. Even if a baker has
bought in stocks of wheat 6 months ago, they will have to adapt their
current bread prices to the fluctuations in the wheat price, since wheat
can in a couple of days be converted into bread. The example Marx cited
of cotton is more analogous to baking than to shipbuilding.