Now by ‘abstract labour’ Marx does not mean, as is commonly thought, some mental generalisation, some mere product of the mind. If this were so – if abstract labour is conceived of as merely a category arrived at by picking some common element found in all labour – then one would be forced inexorably to the conclusion that if abstract labour is a mental image, then so too must be its product, ‘value’. Only concrete labour, producing empirically available use-values would have the status of ‘real’ labour.
Let us, therefore, try to explore in more detail Marx’s notion of abstract labour. The products of labour take the form of commodities when these products are made for exchange on the market. As such, they are the products of autonomous private labour, carried out independently of each other. Each person carries out one determinate form of labour as part of a social division of labour. Of course we must remember that if this social division of labour were a planned one, the products of individual labour would not take the form of commodities. While the production of commodities is impossible without a division of labour, a division of labour is perfectly possible in the absence of commodity production – as in the case cited by Marx of a patriarchal peasant society. Further, under commodity production labour is not immediately social; it becomes social labour only through the mediation of exchange relations on the market.
Now in exchanging products men equalise them – that is, the market, as an objective process, abstracts from the physical-natural aspects in which one use-value differs from another; and in so doing the market abstracts from that which serves to differentiate this labour, Thus:
"Along with the useful qualities of the products themselves, we put out of sight both the useful character of the various kinds of labour embodied in them and the concrete forms of that labour; there is nothing left but what is common to them all . . . human labour in the abstract" (I)
and
"The labour . . . that forms the substance of value is homogeneous labour, expenditure of one uniform labour-power. The total labour-power of society, which is embodied in the sum total of the values of all commodities produced by that society, counts here as one homogeneous mass of human labour-power, composed though it be of innumerable individual units. Each of these units is the same as any other, so far as it has the character of the average labour-power of society, and takes effect as such."(I)
From these quotations alone, it should be clear that in the formation of abstract labour we are not dealing with a mental process, but something that takes place in the actual process of exchange itself.