Part 3: Chapter 9

The "rate of surplus value" is "an exact expression of the degree of exploitation of labor-power by capital, or of the worker by the capitalist."

What anyone will remember about this chapter is the seemingly-arbitrary nature of the time "necessary" to produce the worker's means of subsistence, "if instead of working for the capitalist, he worked independent on his own account." For Marx, without advancing much evidence, this is usually assumed to be ~ six hours. (This, we must of course add, is nationally/historically contingent, but we wonder if it is so contingent in these examples as to be random.) I think we will get far by asking, "How do we know that the worker is not being paid fairly?"

If we flip back to chapter 7, we see that machinery and materials, sitting by themselves, or being worked on, do not create value, but can merely have their own values change shape. And, if the commodity of labor-power were treated only as the time necessary to reproduce itself (i.e. the way that other commodities operate as exchange-values), all values would be quantitatively equal when C was sold and became M again. The first and second M would be the same; capital would not accumulate but would be merely tautological.

This begs the question of all of Marx's previous definitions, however. Whence six hours, then? On one hand, we have to take this on the faith of its continuity with the already-demonstrated part of the system, and on the other, every demonstrated motive of capital as Marx later shows it. And, indeed, as "variable" capital, Marx concedes that there should be nothing fixed about this number, which comes under examination later and at great length. *That* there must be such a number (of hours of strictly "necessary" labor) we must concede, but its exact number is only (here) exemplary or (elsewhere) scrutinized.

Marx's overarching point here is that exploitation must be measured, not absolutely (as in the naive belief that, because overhead is cleared only in the "last hour" of work, that adding every additional hour would double, triple profit), but relatively, in proportion to necessary labor (a variable quantity).