Here are some ways of classifying capital. This post does not talk much about profit on alienation (buying low, selling high). Nor does it talk about analogies (for example, "human capital", "social capital") extending beyond production and, maybe, even economics. The definitions are my attempt to give an off-hand elaboration of the meaning of terms. I have no objection to those offering more authoritative definitions.First division:
- Physical capital: Physical goods that are used in the production of commodities for sale on the market.
- Financial capital: Assets that (can be expected to) generate a stream of money payments. Examples: Annuities, stocks, bonds, a deed for rental property.
- Fixed capital: Capital goods used in producing commodities that are not completely used up in one production cycle. Examples: Machinery, dams.
- Circulating capital: Capital goods used in producing commodities that are completely used up in each production cycle. Examples: fuel for machinery, semi-finished goods that are transformed into produced commodities.
- Constant capital: Capital whose value is transferred unchanged into commodities produced with its aid. Includes both circulating capital and the proportion of constant capital used up, in some sense, in a production cycle.
- Variable capital: Capital whose value yields a surplus in the value of a commodity produced with its aid.
- Means of production: The physical capital goods (commodities) with which commodities are produced.
- Labor power: The ability to labor under the direction of another. Under capitalism, labor power - not labor - is bought or sold.
- Money capital: Finance that the capitalist intends to use to purchase means of production and labor power or the money which produced commodities realizes when they are sold on the market.
- Productive capital: Capital embodied in means of production and labor power when they are being used to produce commodities.
- Commodity capital: Means of production and labor power or the commodities produced by the same for sale on the market.
Update (10 June 2014): I want to note this passage - more succinct than my writing - from Josh Mason:
"We shouldn't ask what capital 'really' is. It really is a quantity of money in a process of self-expansion, and it really is a mass of means of production, and it really is authority over the production process. But the particular historical questions Piketty is interested in may be better suited to thinking of capital as a claim on the social surplus than as a physical quantity of means of production. Seth Ackerman has some very interesting thoughts along these lines in his contribution to the Jacobin symposium on the book. "