For an initial understanding of Marx's economic theory, this definition suffices. However, a little consideration leads us to see that there are problems with this definition, which is why there has been controversy over it, not just from opponents of Marx, but within the ranks of Marxist economists themselves. On the one hand, the easiest way to think of what Marx means, when he talks about Abstract Labour, as Labour with all the peculiarities of concrete labour stripped away, is to think about similar examples. So, for example, the measurement of distance, that we call a foot, originated in the fact that, once, distances were measured out using human feet – indeed, many measures are based on lengths of human body parts. Once it became necessary to have not only more accurate, but standardised measurements of distance, the problem of using “concrete” human feet becomes obvious, and so an “abstract” foot is developed, which is a fixed length.
So, we can think of an hour of Abstract Labour-time in a similar way, but when we do that it then begs many more questions. Exactly, how is this hour of Abstract Labour-time to be decided upon, how is it to be fixed, should it be fixed and so on? Many of these questions are complicated by the fact that Marx himself seems to describe Abstract Labour differently, in various places in Capital. So, for example, he describes Abstract Labour as above, but he also talks about Abstract Labour in terms of being the average of all concrete labour, and an hour of average abstract labour-time being the equivalent of all of social production, divided by the total number of hours of concrete social labour expended to produce it. Elsewhere, he identifies Abstract Labour with the kind of simple, unskilled labour that, he argues, Capitalism was driving all Labour towards. It is he says, that labour, which any human being could perform, requiring only the use of normal muscles, intelligence and so on. But, what is that? The average intelligence today is not what it was 100 years ago. On the other hand, the average person today would be unable to perform the average level of exertion of an unskilled labourer, like a Navvie, from 100 years ago.
If we constantly adjust this kind of measurement of Abstract labour-time, then not only does it mean that the measurement of Value is constantly moving, but it means that Abstract Labour is different in different places at the same time. That would be like changing the physical length of “the foot” as a measurement, every time human feet themselves changed in size! The problem can be explained like this. Suppose we have a society where all the Labour is perfectly homogeneous, so it all equals Abstract Labour. It produces clay pots. It takes 1 hour of its Labour-time to produce a pot. Twenty years later, the technology for producing pots is exactly the same. However, as a result of all workers gaining experience, in pot making, and as a result of every worker benefiting from the lessons handed down to them by the previous generation, the pots now made are of considerably higher quality than in the earlier period. If one of these pots is then compared with the older pots, the producer of the older pot would recognise the higher quality, and the quality of the labour that went into it. Although, it might take only 1 hour of Labour-time of these later workers to produce this higher quality pot, the producer of the earlier pot, recognising the higher quality of the labour that went to produce it, might be prepared to exchange two of their pots for it! Yet, within the same society, we are comparing Abstract Labour-time in both cases.
The question is further complicated by the fact that Marx in Chapter 1 of Capital Volume I, also says that just as the money commodity comes to be the manifestation of Value (Abstract Labour-time), so the concrete labour used to produce the Money Commodity comes to be the manifestation of Abstract Labour.
“Now none of these private labours in its natural form possesses this specifically social form of abstract human labour, just as little as the commodity in its natural form possesses the social form of mere coagulation of labour, or value. However, through the fact that the natural form of a commodity (linen, in this case) becomes a universal Equivalent-form because all other commodities relate themselves to this natural form as the appearance-form of their own value, hence linen-weaving also turns into a universal form of realization of abstract human labour or into labour of immediately social form... Since they are not-immediately social labour, in the first place the social form is a form which differs from the natural forms of the real, useful labours and is foreign to them and abstract; and in the second place, all kinds of private labour obtain their social character only in a contradictory way, by all being equated to one exclusive kind of private labour (linen-weaving, in this case). This latter thereby becomes the immediate and universal form of appearance of abstract human labour and thereby labour in immediately social form. It manifests itself consequently also in a product which is socially valid and universally exchangeable.”
However, there seems a problem to me of using the concrete labour involved in the production of the Money Commodity. For one thing, its not homogeneous. Secondly, it changes, over time and place, as much as any other kind of concrete labour. Thirdly, because it is concrete labour, it could be skilled, in which case, other unskilled concrete labours would have to be assessed as only fractions of an hour of Abstract Labour (not that there is anything technically wrong with that).
Given that science, in the area of the physical sciences, in particular, has moved to ever more precise definitions of the metrics it uses, and ever more accurate measurement of them, it seems to me that a theory of Objective Value has to do likewise. None of the objections to the concept of Abstract Labour invalidate it, or thereby undermine the Labour Theory of Value. For, a theoretical understanding of that theory, the concept of Abstract Labour will suffice. But, it is in my opinion necessary to resolve this matter by establishing a precise definition of Abstract Labour, and a precise and fixed measurement of an Abstract Labour Hour, as the metric by which Value is measured. One way to do that would be to use Marx's method of taking all social production at a given moment in time, and dividing it by the total amount of social labour used in its production, and then reduce this down to that labour which produces the least Value, setting that as 1, and all other concrete labour as multiples of it.
Similarly, all future labour can be compared with, and measured against this labour, in the way that Marx does by measuring its worth according to the Value of its output. A further discussion of Abstract Labour can also be found at:
Abstract Labour & Value In Marx's System - I.I. Rubin