I agree basically with Andrew K. #4611.
There is no a problem to measure on the one hand "abstract labor" and
on the other "concrete labor" because abstract and concrete labor are
NOT two different kinds of labor but aspects of the SAME amount of
labor time, which "is itself measured on the particular sacale of
hours, days, etc." (Capital I, p. 129, Penguin).
Michael's carpenter works 10 hours to produce a table which, we
assume, is the socially necessary labor-time; the table is also sold.
THIS 10 hours have a "double result": on the one hand a *use value*,
a table and on the other a *value* materialized in the table. This
value has a *substance* (10 hours) and a *form*, let's say $100. So
THE SAME 10 hours has a double result, the table and $100. Insofar as
we consider the 10 hours as producing a table, we are consider this
labor in its concrete aspect. Insofar as we consider the 10 hours as
being represented by ("producing) $100, we consider them as abstract
labor.
As a way to support this reading I think it is worth to consider the
following text, where Marx effectively considers "spinner labor" as
"abstract labor". It seems clear to me that the so-called
"measurement problem" doesnt arises. It arises only if we conceive
abstract labor as a kind of element completely different from the
effective spending of labor by workers.
"We have now to consider [the spinner] labour from the standpoint
quite different from that adopted for the labour process... In
that case the labour of the spinner was specifically different
from other kinds of... labour... Here, on the contrary, when we
consider the labor of the spinner only in so far as it creates
value... [it] differs in no respect from... the labour of the
cotton-planter and the spindle maker... It is solely by reason of
this identity that cotton planting, spindle-making and spinning
are capable of forming the component parts of one whole, namely
the value of the yarn, differing only quantitatively from each
other. Here we are no longer concerned with the quality... but
merely with its quantity. And this simply requires to be
calculated... At the end of one hour... a definite quantity of
labour... has been objectified in the cotton.**We say labour, i.e.
the expenditure of his vital force by the spinner, and not
spinning labour, because the special work of spinning counts here
only in so far as it is expenditure of labour-power in general,
and not the specific labor of the spinner.** In the process we are
now considering... only socially necessary labour-time counts
towards the creation of value... If the worker, instead of
spinning, were to be employed in a coal-mine... nevertheless, a
definite quantity of coal... would represent a definite quantity
of absorbed labour. We assumed [that 3 shillings = 6 hours of
labour]... If now our spinner... in 6 hours... convert[s] 10 lb.
of cotton into 10 lb. of yarn... [h]ence... [this is] the same
quantity of labour... embodied in... 3 shillings... Let us now
consider the total value of the product... 2.5 days of labour have
been objectified in it... 2 days were contained [in the means of
production], and 0.5 days was absorbed during the... spinning. This
2.5 days of labour is represented by... 15 shillings.
Capital I (Penguin), pp. 295-7; emphasis added