The theory of abstract labor is one of the central points of Marx's theory of value. According to Marx, abstract labor "creates" value. Marx attached decisive importance to the difference between concrete and abstract labor. "I was the first to point out and to examine critically this two-fold nature of the labor contained in commodities. As this point is the pivot on which a clear comprehension of Political Economy turns, we must go more into detail" (C., I, p. 41). After the publication of the first volume of Capital, Marx wrote Engels: "The best points in my book are: 1) the two-fold character of labor, according to whether it is expressed in use value or exchange value. (All understanding of the facts depends upon this.) It is emphasized immediately, in the first chapter; 2) the treatment of surplus value independently of its particular forms as profit, interest, ground rent, etc." 
When we see the decisive importance which Marx gave to the theory of abstract labor, we must wonder why this theory has received so little attention in Marxist literature. Some writers pass over this question in complete silence. For example, A. Bogdanov transforms abstract labor into "abstractly-simple labor" and, leaving aside the problem of concrete and abstract labor, he restricts himself to the problem of simple and qualified labor.  Many critics of Marxism also prefer to put simple labor in the place of abstract labor, for example Karl Diehl.  In popular presentations of Marx's theory of value, writers paraphrase in their own words the definitions given by Marx in the second section of Chapter 1 of Capital, on the "two-fold character of labor embodied in commodities." Kautsky writes: "On the one hand, labor appears to us as the productive expenditure of human labor-power in general, on the other hand, as specific human activity for the attainment of a given object. The first aspect of labor forms the common element in all the productive activities carried on by men; the second varies with the nature of the activity."  This generally-accepted definition can be reduced to the following, very simple statement: concrete labor is the expenditure of human energy in a determined form (clothesmaking, weaving, etc.). Abstract labor is the expenditure of human energy as such, independently of the given forms. Defined in this way, the concept of abstract labor is a physiological concept, devoid of all social and historical elements. The concept of abstract labor exists in all historical epochs independently of this or that social form of production.
If even Marxists usually define abstract labor in the sense of expenditure of physiological energy, then we need not wonder that this concept is widespread in anti-Marxist literature. For example, according to P. Struve: "From the Physiocrats and their English successors, Marx accepted the mechanical-naturalistic point of view which is so striking in his theory of labor as the substance of value. This theory is the crown of all objective theories of value. It directly materializes value, transforming it into the economic substance of economic goods, similar to the physical matter which is the substance of physical things. This economic substance is something material, because the labor which creates value is understood by Marx in a purely physical sense as an abstract expenditure of nervous and muscular energy, independently of the concrete purposeful content of this expenditure, which is distinguished by infinite variety. Marx's abstract labor is a physiological concept, an ideal concept, and in the last analysis a concept which can be reduced to mechanical work" (Struve's foreword to the Russian edition of Volume I of Capital, 1906, p. 28). According to Struve, abstract labor is a physiological concept for Marx; that is why the value created by abstract labor is something material. This interpretation is shared by other critics of Marx. Gerlach noted that according to Marx, "value is something which is common to all commodities, it is the condition for their exchangeability, and represents a reification of abstract-human labor."  Gerlach directs his critical observations against this point of Marx's theory of value: "It is completely impossible to reduce human labor to simple labor physiologically. .. Since human labor is alwaysaccompanied and conditioned by consciousness, we must refuse to reduce it to the movement of muscles and nerves, because in this reduction there is always some kind of remainder which is not amenable to similar analysis" (Ibid., pp. 49-50). "Earlier attempts to show, experimentally, abstract human labor, that which is general in human labor, which is its specific distinction, did not succeed; the reduction of labor to nervous and muscular energy is not possible" (Ibid., p. 50). Gerlach's statement that labor cannot be reduced to the expenditure of physiological energy, because it always contains a conscious element, cannot be related in any way to the concept of "abstract labor" which was created by Marx on the basis of his analysis of the properties of the commodity economy. However, these arguments of Gerlach seem so convincing that they are often repeated by critics of Marx's theory of value.  We find an even more striking version of a naturalistic conception of abstract labor in the work of L. Buch: labor, in abstract form, is treated "as the process of transformation of potential energy into mechanical work."  Here the attention is directed not so much to the quantity of physiological energy which was expended, but rather to the quantity of mechanical labor received. But the theoretical basis of the problem is purely naturalistic, completely neglecting the social aspect of the labor process, i.e., precisely the aspect which is the direct subject of political economy.
Only a few analysts understand that the characteristics of abstract labor do not in any way coincide with a physiological equality of different labor expenditures. "The universal character of labor is not a concept of natural science which includes only a physiological content. Private labor is abstract-universal and thus also social, as the expression of the activity of holders of rights."  But the general conception of Petry, for whom Marx's theory of value does not represent Wertgesetz but Wertbetrachtung, is not an explanation of a "real process in objects," but a "subjective condition of knowledge" (Ibid., p. 50). This deprives Petry of any possibility of formulating the problem of abstract labor accurately. 
Another attempt to introduce a social aspect into the concept of abstract labor is found in the work of A. Nezhdanov (Cherevanin). According to Nezhdanov, the concept of abstract labor does not express a physiological equality of labor expenditures, but a social process of equalization of different forms of labor in production. This is "an important and indispensable social process which is carried out by every conscious social-economic organization.... This social process which characterizes the reduction of different forms of labor to abstract labor is carried out unconsciously in the commodity society."  Taking abstract labor as an expression of the process of equalization of labor in every economy, A. Nezhdanov neglects the particular form which the equalization of labor acquires in a commodity economy; here it is not carried out directly in the process of production, but through exchange. The concept of abstract labor expresses the specific historical form of equalization of labor. It is not only a social, but also a historical concept.
We can see that the majority of writers understood abstract labor in a simplified way - in the sense of physiological labor. This is due to the fact that these writers did not apply themselves to follow Marx's theory of abstract labor in its entirety. To do this they would have had to turn to a detailed analysis of Marx's text in the section on commodity fetishism, and in particular in A Contribution to the Critique of Political Economy, where Marx developed this theory most completely. Instead, these writers preferred to confine themselves to a literal repetition of a few sentences which Marx devoted to abstract labor in the second section of Chapter 1 of Capital.
In the above-mentioned section of Capital, Marx does, in fact, seem to give a basis for the interpretation of abstract labor precisely in a physiological manner. "Productive activity, if we leave out of sight its special form, viz., the useful character of the labor, is nothing but the expenditure of human labor-power. Tailoring and weaving, though qualitatively different productive activities, are each a productive expenditure of human brains, nerves, and muscles, and in this sense are human labor" (C., I, p. 44). And, in concluding, Marx stresses this idea still more sharply: "On the one hand all labor is, speaking physiologically, an expenditure of human labor-power, and in its character of identical abstract human labor, it creates and forms the value of commodities. On the other hand, all labor is the expenditure of human labor-power in a special form and with a definite aim, and in this, its character of concrete useful labor, it produces use-values" (C, I, p. 46). Supporters as well as opponents of Marx find support in the cited passages and understand abstract labor in a physiological sense. The first repeat this definition, not analyzing it critically. The others bring against it a whole series of objections and sometimes they make of this the starting-point for the refutation of the labor theory of value. Neither the former nor the latter notice that the simplified conception of abstract labor (which was presented above), at first glance based on a literal interpretation of Marx's words, cannot in any way be made consistent with the entirety of Marx's theory of value, not with a series of individual passages in Capital.
Marx never tired of repeating that value is a social phenomenon, that the existence of value (Wertgegenstandlichkeit) has "a purely social reality" (C., I, p. 47), and does not include a single atom of matter. From this it follows that abstract labor, which creates value, must be understood as a social category in which we cannot find a single atom of matter. One of two things is possible: if abstract labor is an expenditure of human energy in physiological form, then value also has a reified-material character. Or value is a social phenomenon, and then abstract labor must also be understood as a social phenomenon connected with a determined social form of production. It is not possible to reconcile a physiological concept of abstract labor with the historical character of the value which it creates. The physiological expenditure of energy as such is the same for all epochs and, one might say, this energy created value in all epochs. We arrive at the crudest interpretation of the theory of value, one which sharply contradicts Marx's theory.
There can be only one way out of these difficulties: since the concept of value has a social and historical character in Marx's work (and this is precisely his service and the distinctive feature of his theory), then we must construct the concept of the abstract labor which creates value on the same basis. If we do not stay with the preliminary definitions which Marx gave on the first pages of his work, and if we apply ourselves to trace the further development of his thought, we will find in Marx's work enough elements for a sociological theory of abstract labor.
To grasp Marx's theory of abstract labor accurately, we cannot for a minute forget that Marx puts the concept of abstract labor into inseparable connection with the concept of value. Abstract labor "creates" value, it is the "content" or "substance" of value. Marx's task was (as we have frequently noted) not to reduce value analytically to abstract labor, but to derive value dialectically from abstract labor. And this is not possible if abstract labor is understood as nothing other than labor in a physiological sense. Thus it is not accidental that the writers who consistently hold a physiological interpretation of abstract labor are forced to reach conclusions which sharply contradict Marx's theory, namely to conclude that abstract labor in itself does not create value.  Whoever wants to maintain Marx's well-known statement that abstract labor creates value and is expressed in value, must renounce the physiological concept of abstract labor. But this does not mean that we deny the obvious fact that in every social form of economy the working activity of people is carried out through the expenditure of physiological energy. Physiological labor is the presupposition of abstract labor in the sense that one cannot speak of abstract labor if there is no expenditure of physiological energy on the part of people. But this expenditure of physiological energy remains precisely a presupposition, and not the object of our analysis.
In every social form of economy, human labor is at the same time material-technical and physiological labor. The first quality is possessed by labor only to the extent that the labor is subjected to a definite technical plan and directed to the production of products necessary for the satisfaction of human needs; the second quality is possessed by labor only to the extent that labor represents an expenditure of physiological energy which is accumulated in the human organism and which must regularly be restored. If labor did not create useful products, or if it was not accompanied by the expenditure of the energy of the human organism, the entire picture of the economic life of humanity would be completely different from what it actually is. Thus labor which is treated in isolation from this or that social organization of economy is a material-technical as well as a biological presupposition for all economic activity. But this presupposition of economic research cannot be transformed into the object of analysis. The expenditure of physiological energy as such isnot abstract labor and does not create value.
Until now we have examined the physiological version of abstract labor in its crudest form. The adherents to this crude form hold that the value of the product is created by abstract labor as an expenditure of a certain sum of physiological energy. But there are also finer formulations of this physiological interpretation, which approximately hold: the equality of products as values is created through the equality of all forms of human labor as expenditures of physiological energy. Here labor is no longer treated simply as the expenditure of a certain sum of physiological energy, but in terms of its physiological homogeneity with all other forms of labor. Here the human organism is not treated merely as the source of physiological energy in general, but also as the source which is able to furnish labor in any concrete form. The concept of physiological labor in general has been transformed into a concept of physiologically equal or homogeneous labor.
However, this physiologically homogeneous labor is not the object but rather the presupposition of economic research. In reality, if labor as the expenditure of physiological energy is a biological presupposition of any human economy, then the physiological homogeneity of labor is a biological presupposition of any social division of labor. The physical homogeneity of human labor is an indispensable presupposition for the transfer of people from one to another form of labor and, thus, for the possibility of the social process of redistribution of social labor. If people were born as bees and ants, with determined working instincts which in advance limited their working capacities to one form of activity, then the division of labor would be a biological fact, and not a social one. If social labor is to be carried out in one or another sphere of production, every individual must be able to pass from one form of labor to another.
Thus the physiological equality of labor is a necessary condition for the social equalization and distribution of labor in general. Only on the basis of the physiological equality and homogeneity of human labor, i.e., the variety and flexibility of the working activity of people, is the transfer from one activity to another possible. The origin of the social system of division of labor, and in particular the system of commodity production, is only possible on this basis. Thus when we speak of abstract labor, we presuppose labor which is socially equalized, and the social equalization of labor presupposes the physiological homogeneity of labor without which the social division of labor as a social process could not be carried out in any form.
The physiological homogeneity of human labor is a biological presupposition, and not a cause of the development of the social division of labor. (This presupposition, in turn, is a result of the long process of human development, and in particular of the development of instruments of labor and of some organs of the body: the hand and the brain.) The level of development and the forms of social division of labor are determined by purely social causes and they, in turn, determine the extent to which the variety of working operations which the human organism can potentially perform, are actually manifested in the variety of working operations of men as members of society. In a strictly enforced caste system, the physiological homogeneity of human labor cannot be expressed to a significant extent. In a small community based on a division of labor, the physiological homogeneity of labor is manifested in a small circle of people, and the human character of labor cannot be expressed. Only on the basis of commodity production, characterized by a wide development of exchange, a mass transfer of individuals from one activity to another, and indifference of individuals towards the concrete form of labor, is it possible to develop the homogeneous character of all working operations as forms of human labor in general. The physiological homogeneity of human labor was a necessary presupposition of the social division of labor, but only at a determined level of social development and in a determined social form of economy does the labor of the individual have the character of a form of manifestation of human labor in general. We would not be exaggerating if we said that perhaps the concept of man in general and of human labor in general emerged on the basis of the commodity economy. This is precisely what Marx wanted to point out when he indicated that the general human character of labor is expressed in abstract labor.
We have come to the conclusion that physiological labor in general, or physiologically equal labor, are not in themselves abstract labor, even though they are its assumptions. The equal labor which is expressed in the equality of value must be treated as socially equalized labor. Since the value of the product of labor is a social and not a natural function, so labor, which creates this value, is not a physiological but a "social substance." Marx expressed this idea clearly and briefly in his work Wages, Price and Profit: "As the exchangeable values of commodities are only social functions of those things, and have nothing at all to do with their natural qualities, we must first ask, What is the common social substance of all commodities? It is Labor. To produce a commodity a certain amount of labor must be bestowed upon it, or worked up in it. And I say not only Labor, but social Labor."  And to the extent that this labor is equal, what is under consideration is socially equal, or socially equalized, labor.
Thus we must not limit ourselves to the characteristic of labor as equal, but must distinguish three types of equal labor, as we mentioned in Chapter Eleven:
1) physiologically equal labor
2) socially equalized labor
3) abstract, or abstract-universal labor, i.e., socially equalized labor in the specific form which it acquires in a commodity economy.
Although abstract labor is a specific property of a commodity economy, socially equalized labor can be found, for example, in a socialist commune. Abstract labor does not only fail to coincide with physiologically equal labor but cannot be identified with socially equalized labor at all (see, above, Chapter Eleven). Every abstract labor is social and socially equalized labor, but not every socially equalized labor can be considered abstract labor. For socially equalized labor to take the specific form of abstract labor characteristic of the commodity economy, two conditions are necessary, as was accurately shown by Marx: It is necessary that: 1) the equality of different kinds of labor and of individuals expresses "the specific social character of private labor carried on independently" (C., I, P. 74), i.e., that labor become social labor only as equal labor, and 2) that this equalization of labor take place in a material form, i.e., "assumes in the product the form of value"(Ibid.).  I, the absence of these conditions, labor is physiologically equal. It can also be socially equalized, but it is not abstract-universal labor.
If some writers erroneously confuse abstract labor with physiologically equal labor, other writers commit an equally unacceptable, though not as crude, error: they confuse abstract labor with socially equalized labor. Their reasoning can be reduced to the following terms: the organ of a socialist commune, as we have seen, equalizes labor of different forms and individuals, for the purpose of accounting and distribution of labor, i.e., it reduces all labor to a general unit which is necessarily abstract; thus labor acquires the character of abstract labor.  If these writers insist they are right in calling socially equalized labor "abstract," we can recognize their right to do this: every writer has the right to give any term he chooses to a phenomenon, even though such arbitrary terminology can be very dangerous and creates great confusion in science. But our argument is not over the term which is given to socially equalized labor, but over something different. We confront the question: what do we understand by that "abstract labor" which creates value and is expressed in value, according to Marx's theory. We must again mention that Marx did not only want to analytically reduce value to labor, but also to analytically derive value from labor. And from this point of view it is clear that neither physiologically equal nor socially equalized labor as such create value. The abstract labor which Marx treated is not only socially equalized labor but socially equalized labor in a specific form which is characteristic for a commodity economy. In Marx's system, the concept of abstract labor is inseparably related to the basic characteristics of the commodity economy. In order to prove this we must explain in greater detail Marx's views of the character of abstract labor.
Marx begins his analysis with commodities, in which he distinguishes two sides: the material-technical and the social (i.e., use value and value). Similar two sides are distinguished by Marx in the labor embodied in commodities. Concrete and abstract labor are two sides (material-technical and social) of one and the same labor embodied in commodities. The social side of this labor, which creates value and is expressed in value, is abstract labor.
We begin with the definition which Marx gives of concrete labor. "So far therefore as labor is a creator of use-value, is useful labor, it is a necessary condition, independent of all forms of society, for the existence of the human race; it is an eternal nature-imposed necessity, without which there can be no material exchanges between man and Nature, and therefore no life" (C., I, pp. 42-43; Rubin's italics). It is obvious that abstract labor is contrasted to concrete labor. Abstract labor is related to a definite "social form," and expresses determined relations of man to man in the process of production. Concrete labor is the definition of labor in terms of its material-technical properties. Abstract labor includes the definition of social forms of organization of human labor. This is not a generic and specific definition of labor, but the analysis of labor from two standpoints: the material-technical and the social. The concept of abstract labor expresses the characteristics of the social organization of labor in a commodity - capitalist society. 
For an accurate interpretation of the opposition between concrete and abstract labor, one must start with the opposition which Marx drew between private and social labor, and which we have examined above.
Labor is social if it is examined as part of the total mass of homogeneous social labor or, as Marx frequently said, if it is seen in terms of its "relation to the total labor of society." In a large socialist community, the labor of the members of the community, in its concrete form (for example, the labor of a shoemaker), is directly included in the unified working mechanism of society, and is equalized with a determined number of units of social labor (if we refer to the early phase of a socialist economy, when the labor of individuals is still evaluated by society - see the end of this chapter for a more detailed examination of this topic). Labor in its concrete form is in this case directly social labor. It is different in a commodity economy where the concrete labor of producers is not directly social labor but private, i.e., labor of a private commodity producer, a private owner of means of production and an autonomous organizer of economic activity. This private labor can become social only through its equalization with all other forms of labor, through the equalization of their products (see above, Chapter Eleven). In other words, concrete labor does not become social because it has the form of concrete labor which produces concrete use values, for example shoes, but only if the shoes are equalized as values with a given sum of money (and through the money with all other products as values). Thus the labor materialized in the shoes is equalized with all other forms of labor and, consequently, sheds its determined concrete form and becomes impersonal labor, a particle of the entire mass of homogeneous social labor. Similarly, just as the concrete products of labor (for example shoes) display their character as value only if the product sheds its concrete form and is equalized with a given sum of abstract monetary units, so the private and concrete labor contained in the product displays its character as social labor only if it sheds its concrete form and is equalized, in a given proportion. with all other forms of labor, i.e., is equalized with a given quantity of impersonal, homogeneous, abstract labor, "labor in general." The transformation of private labor into social labor can only be carried out through the transformation of concrete labor into abstract labor. On the other hand, the transformation of concrete into abstract labor already signifies its inclusion in the mass of homogeneous social labor, i.e., its transformation into social labor. Abstract labor is the variety of social labor or socially equalized labor in general. It is social or socially equalized labor in the specific form which it has in a commodity economy. Abstract labor is not only socially equalized labor, i.e., abstracted from concrete properties, impersonal and homogeneous labor. It is labor which becomes social labor only as impersonal and homogeneous labor. The concept of abstract labor presupposes that the process of impersonalization or equalization of labor is a unified process through which labor is "socialized," i.e., is included in the total mass of social labor. This equalization of labor may take place, but only mentally and in anticipation, in the process of direct production, before the act of exchange. But in reality, it takes place through the act of exchange, through the equalization (even though it is mental and anticipated) of the product of the given labor with a definite sum of money. If this equalization precedes exchange, it must yet be realized in the actual process of exchange.
The role of labor we have described is characteristic of it precisely in a commodity economy and is especially striking if the commodity society is compared with other forms of economy. "Let us take the services and payments in kind of the Middle Ages. It was the specific  kind of labor performed by each individual in its natural form, the particular and nor the universal  aspect of labor, that constituted then the social tie. Or, let us finally take labor carried on in common in its primitive natural form, as we find it at the dawn of history of all [cultures]. It is clear that in this case labor does not acquire its social character from the fact that the labor of the individual takes on the abstract form of universal labor or that his product assumes the form of a universal equivalent. The very nature of production under a communal system makes it impossible for the labor of the individual to be private labor and his product to be a private product; on the contrary, it makes individual labor appear as the direct function of a member of a social organism. On the contrary, labor, which is expressed in exchange value, at once appears as the labor of a separate individual. It becomes social labor only by taking on the form of its direct opposite, the form of abstract universal labor" (Critique, pp. 29-30; Rubin's italics). The same idea was repeated by Marx in Capital. He says of medieval society: "Here the particular and natural form of labor, and not, as in a society based on production of commodities, its general abstract form is the immediate social form of labor" (C, I, p. 77). In the same way, in the agricultural production of a patriarchal peasant family, "the different kinds of labor, such as tillage, cattle tending, spinning, weaving and making clothes, which result in the various products, are in themselves, and such as they are, direct social functions" (Ibid., p. 78).
Thus, as opposed to a patriarchal family or a feudal estate, where labor in its concrete form had a directly social character, in the commodity society the only social relation among independent, private economic units is realized through a many-sided exchange and equalization of the products of the most varied concrete forms of labor, i.e., through abstraction from their concrete properties, through the transformation of concrete to abstract labor. The expenditure of human energy as such, in a physiological sense, is still not abstract labor, labor which creates value, even though this is its premise. Abstraction from the concrete forms of labor, the basic social relation among separate commodity producers, is what characterizes abstract labor. The concept of abstract labor presupposes a determined social form of organization of labor in a commodity economy: the individual commodity producers are not directly connected in the production process itself to the extent that this process represents the totality of concrete working activities; this connection is realized through the process of exchange, i.e., through abstraction from those concrete properties. Abstract labor is not a physiological category, but a social and historical category. Abstract labor differs from concrete labor not only in terms of its negative properties (abstraction from concrete forms of labor) but also in terms of its positive property (the equalization of all forms of labor in a many-sided exchange of the products of labor). "The labor realized in the values of commodities is presented not only under its negative aspect, under which abstraction is made from every concrete form and useful property of actual work, but its own positive nature is made to reveal itself expressly. The general value-form is the reduction of all kinds of actual labor to their common character of being human labor generally, of being the expenditure of human labor-power" (C., I p. 67). In other passages Marx emphasizes that this reduction of concrete forms of labor to abstract labor is carried out definitively in the process of exchange. However, in the process of direct production this reduction has an anticipated or ideal character, since production is designated for exchange (see below). In Marx's theory of value, the transformation of concrete into abstract labor is not a theoretical act of abstracting for the purpose of finding a general unit of measurement. This transformation is a real social event. The theoretical expression of this social event, namely the social equalization of different forms of labor and not their physiological equality, is the category of abstract labor. The neglect of this positive, social nature of abstract labor has led to the interpretation of abstract labor as a calculation of labor expenditures in a physiological sense, namely a purely negative property of abstracting from the specific forms of concrete labor.
Abstract labor appears and develops to the extent that exchange becomes the social form of the process of production, thus transforming the production process into commodity production. In the absence of exchange as the social form of production, there can be no abstract labor. Thus to the extent that the market and the sphere of exchange is widespread, to the extent that individual economic units are drawn into exchange, to the extent that these units are transformed into a unified social economy and later into a world economy, the characteristic properties of labor which we have called abstract labor are strengthened. Thus Marx wrote: "only foreign trade, the development of the market into a world market, transform money into world money and abstract labor into social labor. Abstract wealth, value, money - consequently abstract labor, are developed to the extent that concrete labor develops into the totality of the varied forms of labor encompassed by the world market" (Theorien uber den Mehrwert, III, p. 301; Marx's italics). When exchange is restricted within national boundaries, abstract labor does not yet exist in its most developed form. The abstract character of labor achieves its completion when international trade connects and unifies all countries, and when the product of national labor loses its specific concrete properties because it is delivered to the world market and equalized with the products of labor of the most varied national industries. This concept of abstract labor is indeed far from the concept of labor expenditures in a physiological sense, without reference either to the qualitative properties of working activity or to the social forms of the organization of labor.
In production based on exchange, the producer is not interested in the use value of the product he makes, but exclusively in its value. The products do not interest him as results of concrete labor, but as the result of abstract labor, i.e., to the extent that they can shed their innate useful form and be transformed into money, and through money into an infinite series of different use values. If, from the standpoint of value, a given occupation is less advantageous for a producer than another occupation, he passes from one concrete activity to another, presupposing that in the commodity economy there is full mobility of labor. Exchange creates the indifference of the producer towards his concrete labor (obviously in the form of a tendency which is interrupted and weakened by counteracting influences). "The indifference to the particular kind of labor corresponds to a form of society in which individuals pass with ease from one kind of work to another, which makes it immaterial to them what particular kind of work may fall to their share. Labor has become here, not only categorically but really, a means of creating wealth in general and is no longer grown together with the individual into one particular destination. This state of affairs has found its highest development in the most modern of bourgeois societies, the United States. It is only here that the abstraction of the category 'labor,' 'labor in general,' labor sans phrase, the starting point of modern political economy, becomes realized in practice. Thus, the simplest abstraction which modern political economy sets up as its starting point, and which expresses a relation dating back to antiquity and prevalent under all forms of society, appears in this abstraction truly realized only as a category of the most modern society. ....This example of labor strikingly shows how even the most abstract categories, in spite of their applicability to all epochs - just because of their abstract character - are by the very definiteness of the abstraction a product of historical conditions as well, and are fully applicable only to and under those conditions."  We have cited this long excerpt from Marx's work because here he definitively demonstrated the impossibility of defining "abstract labor" or "labor in general" physiologically. "Labor in general" at first glance exists in all forms of society, but in reality it is a product of historical conditions of a commodity economy and "possesses full significance" only in this economy. Abstract labor becomes a social relation among the members of society if it is realized through exchange and through equalization of products of the most varied forms of labor: "in the world of commodities the character possessed by all labor of being human labor constitutes its specific social character" (C., I, p. 67), and only this social character of labor abstracted from concrete properties gives it the character of abstract labor which creates value. In value "the general character of individual labor" appears "as its social character" - Marx repeats this idea constantly in A Contribution to the Critique of Political Economy.
Thus, to the extent that value can be dialectically derived from labor, we must understand by labor that labor which is organized in the determined social form which exists in a commodity economy. When we speak of physiologically equal or even of socially equalized labor in general, this labor does not create value. One can approach another, less concrete concept of labor only by restricting the task to a purely analytical reduction of value to labor. If we start with value as a finished, given social form of the product of labor (which does not require a particular explanation) and if we ask, to what labor can this value be reduced, we answer briefly: to equal labor. In other words, if value can be dialectically derived only from abstract labor which is distinguished by a concrete social form, the analytical reduction of value to labor can be restricted to the definition of the character of labor as socially equalized in general,  or even physiologically equal labor. It is possible that precisely this explains the fact that in the second section of Chapter I of the first volume of Capital, Marx reduced value to labor by the analytical method and underlined the character of labor as physiologically equal, no longer dwelling on the social form of organization of labor in the commodity economy.  On the other hand, wherever Marx wants to derive valuedialectially from abstract labor, he emphasizes the social form of labor in the commodity economy as the characteristic of abstract labor.
Since we have explained the social nature of abstract labor and its relation to the process of exchange, we must answer certain critical observations  which were raised against our conception of abstract labor. Some critics say that our conception may lead to the conclusion that abstract labor originates only in the act of exchange, from which it follows that value also originates only in exchange. However, from Marx's point of view, value, and thus also abstract labor, must already exist in the process of production. This borders on a very serious and profound question of the relation between production and exchange. How should we resolve this problem? On one hand, value and abstract labor must already exist in the process of exchange, yet on the other hand, Marx in several passages says that abstract labor presupposes the process of exchange.
We can cite several examples. According to Marx, Franklin perceived labor as abstract, but did not grasp that it was abstractly general, social labor which arises from the complete alienation of individual labor (Critique, pp. 62-64). Franklin's main error was thus that he did not take into consideration the fact that abstract labor arises from the alienation of individual labor.
This case does not refer to an isolated phrase in Marx's work. In later editions of Capital, Marx, with increasing sharpness, underlined the idea that in a commodity economy only exchange transforms concrete labor into abstract labor.
We can examine the well-known passage which we cited earlier: "when we bring the products of our labor into relation with each other as values, it is not because we see in these articles the material receptacles of homogeneous human labor. Quite the contrary: whenever, by an exchange, we equate as values our different products, by that very act, we also equate, as human labor, the different kinds of labor expended upon them" (C., I, p. 74). In the first edition of Capital this passage had precisely the opposite meaning. In Marx's original work this passage said: "People relate their products to each other as values to the extent that these things are for them only material shells of homogeneous human labor," etc. (Kapital, 1, 1867, p. 38.) In order to avoid being interpreted to mean that people consciously equalize their labor with each other in advance as abstract, Marx completely changed the meaning of his sentence in the second edition, and he underlined the meaning that the equalization of labor as abstract labor takes place only through the exchange of products of labor. This is a significant change between the first and the second editions.
But as we mentioned, Marx did not restrict himself to the second edition of Volume I of Capital. He still corrected the later text for the French edition of 1875. There he wrote that he had introduced those changes which he had not been able to include in the second German edition. On this basis Marx assigned to the French edition of Capital an independent scientific value parallel with that of the German original.
In the second edition of Capital we find the well-known sentence: "The equalization of the most different kinds of labor can be the result only of an abstraction from their inequalities, or of reducing them to their common denominator, viz., expenditure of human labor-power or human labor in the abstract" (C., I, p. 73). In the French edition Marx, at the end of this sentence, replaced the period with a comma and added: "and only exchange brings about this reduction, opposing the products of different forms of labor with each other on the basis of equality" (French edition of Capital, 1875, p 29). This insertion is significant and strikingly shows how far Marx was from the physiological interpretation of abstract labor. How can we reconcile these statements of Marx, which can be multiplied, with his basic view that value is created in production?
It is not hard to reconcile these views.
The problem is that in treating the question of the relation between exchange and production two concepts of exchange are not adequately distinguished. We must distinguish exchange as a social form of the process of reproduction from exchange as a particular phase of this process of reproduction, alternating with the phase of direct production.
At first glance it seems that exchange is a separate phase of the process of reproduction. We can see that the process of direct production comes first, and the phase of exchange comes next. Here exchange is separate from production and stands opposite from it. But exchange is not only a separate phase of the process of reproduction; it puts its specific imprint on the entire process of reproduction. It is a particular social form of the social process of production. Production based on private exchange - these are words with which Marx frequently characterized a commodity economy. From this point of view, "the exchange of products as commodities is a determined form of social labor or social production" (Theorien uber den Mehrwert, III, 1921, p. 153). If we pay attention to the fact that exchange is a social form of the production process, a form which leaves its imprint on the course of the process of production itself, then many of Marx's statements will become completely clear. When Marx constantly repeats that abstract labor is only the result of exchange, this means that it is the result of a given social form of the production process. Only to the extent that the process of production acquires the form of commodity production, i.e., production based on exchange, labor acquires the form of abstract labor and products of labor acquire the form of value.
Thus exchange is above all a form of production process, or a form of social labor. Since exchange is actually the dominant form of the process of production, it leaves its imprint on the phase of direct production. In other words, since a person produces after he has entered the act of exchange, and before he enters the next act of exchange, the process of direct production acquires determined social properties which correspond to the organization of the commodity economy based on exchange. Even though the commodity producer is still in his workshop and in a given moment does not enter into exchange with other members of society, he already feels the pressure of all those persons who enter the market as his buyers, competitors, people who buy from his competitors, etc., in the last analysis, the pressure of all members of society. This economic relation and these production relations, which are directly realized in exchange, extend their influence even after the given concrete acts of exchange have ended. These acts leave a sharp social imprint on the individual and on the product of his labor. Already in the very process of direct production, the producer appears as a commodity producer, his labor has the character of abstract labor, and his product has the character of value.
Here, however, it is necessary to beware of the following errors. Many writers think that since the process of direct production already possesses determined social properties, this means that the products of labor, and labor, in the phase of direct production, are characterized point by point by the same social properties which characterize them in the phase of exchange. Such an assumption is erroneous because, even though both phases (the phase of production and the phase of exchange) are closely related to each other, this does not mean that the phase of production has become the phase of exchange. There is a certain similarly between the two phases, but a certain difference has also been preserved. In other words we recognize that from the moment when exchange becomes the dominant form of social labor and people produce especially for exchange, the character of the product of labor as a value is taken into consideration in the phase of direct production. But this character of the product of labor as a value is not yet that character which it acquires when it is in fact exchanged for money, when, in Marx's terms, its "ideal" value is transformed into "real" value, and the social form of commodities is substituted by the social form of money.
This is also true of labor. We know that commodity producers, in their acts of production, take into consideration the state of the market and of demand during the process of direct production. They produce exclusively in order to transform their product into money, and thus their private and concrete labor into social and abstract labor. But this inclusion of the labor of the individual into the working mechanism of the entire society is only preliminary and surmised: it is still subject to very rough verification in the process of exchange, verification which can give positive or negative results for the given commodity producer. Thus the working activity of commodity producers in the phase of production is directly private and concrete labor, and it is social labor only indirectly, or latently, as Marx put it.
Thus when we read Marx's work, and particularly his descriptions of how exchange influences value and abstract labor, we must always ask what Marx had in mind in a given case - exchange as the form of the production process itself, or exchange as a separate phase which is opposed to the phase of production. To the extent that he deals with exchange as a form of the production process, Marx clearly says that without exchange there is neither abstract labor nor value. Labor acquires the character of abstract labor only to the extent that exchange develops. When Marx speaks of exchange as a separate phase which stands in opposition to production, he says that even before the process of exchange, labor and the product of labor possess determined social characteristics but that these characteristics must be realized in the process of exchange. In the process of direct production labor is not yet abstract labor in the full sense of the word, it must still become (werden) abstract labor. Numerous statements to this effect can be found in Marx's works. We can cite two passages from the Critique: "As a matter of fact, the individual labors which are represented in these particular use-values, become [werden] universal, and, in this form, also social labor, only when they are actually exchanged for one another in proportion to the labor-time contained in them. Social labor-time exists in these commodities in a latent state, so to say, and is first revealed [offenbart sich] in the process of exchange" (Critique, p. 46). Elsewhere Marx writes: "Commodities now confront one another in a double capacity: actually as use-values, ideally as exchange values. The twofold aspect of labor contained in them is reflected in their mutual relations; the special concrete labor being virtually present as their use-value, while universal abstract labor-time is ideally represented [vorgestelltes Dasein] in their price" (Ibid., p. 80).
Marx holds that commodities and money do not lose their differences because of the fact that every commodity must be transformed into money; each of these is in reality what the other is ideally, and ideally what the first is in reality. All of these statements show that we must not think of the problem too literally. We should not think that, since in the process of direct production commodity producers are directly connected to each other by production relations, therefore their products and their labor already possess a directly social character. Reality is not like this. The labor of commodity producers is directly private and concrete, but it acquires a supplementary, "ideal" or "latent" social property in the form of abstract-general and social labor. Marx always laughed at the Utopians who dreamed of the disappearance of money and believed in the dogma that "the isolated labor of the individual contained in [a commodity] is direct social labor" (Critique, p. 106).
Now we must answer the following question: can abstract labor, which we treat as a purely "social substance," have a quantitative determination, i.e., a determined magnitude? It is obvious that from the standpoint of Marx's theory, abstract labor has a determined magnitude, and precisely because of this the product of labor does not only acquire the social form of value but has a value of determined magnitude. In order to grasp the possibility of the quantitative characterization of abstract labor,we must again resort to the comparison of abstract labor with the socially equalized labor which is found in a socialist community. We suppose that the organs of the socialist community equalize labor of different types and of different individuals. For example, one day of simple labor is taken as 1 unit, and a day of qualified labor as 3 units; a day of the labor of experienced worker A is taken as equal to two days of the labor of inexperienced worker B, and so on. On the basis of these general principles, the organs of social accounting know that worker A expended in the social process of production 20 units of labor, and worker B, 10 units of labor. Does this mean that A really worked two times longer than B? Not at all. Even less does this computation mean that A spent two times more physiological energy than B. From the point of view of the actual length of time of their work, it is possible that A and B worked an equal number of hours. It is possible that from the standpoint of the quantity of physiological energy expended in the process of labor, A spent less energy than B. Nevertheless, the quantity of "social labor" which is the share of A is larger than the quantity of labor which is the share of B. This labor represents a purely "social substance." The units of this labor are units of a homogeneous mass of social labor, calculated and equalized by social organs. At the same time, this social labor has a thoroughly determined magnitude but (and one must not forget this) a magnitude of a purely social character. The 20 units of labor which are the share of A do not represent a number of working hours, and not a sum of actually expended physiological energy, but a number of units of social labor, i.e., a social magnitude. Abstract labor is precisely a social magnitude of this type. In a spontaneous commodity economy, it plays the role which socially equalized labor plays in a consciously organized socialist economy. Thus Marx constantly mentions that abstract labor is a "social substance" and its magnitude a "social magnitude."
Only through such a sociological interpretation of abstract labor can we understand Marx's central proposition that abstract labor "creates" value or finds its expression in the form of value. The physiological conception of abstract labor could easily lead to a naturalistic concept of value, to a conception which sharply contradicts Marx's theory. According to Marx, abstract labor and value are distinguished by the same social nature and represent purely social magnitudes. Abstract labor means "social determination of labor," and value, the social property of the product of labor. Only abstract labor, which presupposes determined production relations among people, creates value, and not labor in the material-technical or physiological sense.  The relations between abstract labor and value cannot be thought of as relations between physical causes and physical effects. Value is a material expression of social labor in the specific form which labor possesses in a commodity economy, i.e., abstract labor. This means that value is "congealed" labor, "a mere congelation of homogeneous human labor," "crystals of the social substance" of labor (C., I, p. 38). For these remarks, Marx was frequently attacked and accused of a "naturalistic" construction of the theory of value. But these remarks can be grasped properly only by comparing them with Marx's theory of commodity fetishism and the "reification" of social relations. Marx's first postulate is that social production relations among people are expressed in a material form. From this it follows that social (namely abstract) labor is expressed in the form of value. Thus value is "reified," "materialized" labor and simultaneously it is an expression of production relations among people. These two definitions of value contradict each other if one deals with physiological labor; but they perfectly supplement each other if one deals with social labor. Abstract labor and value have a social and not a material-technical or physiological nature. Value is a social property (or a social form) of a product of labor, just as abstract labor is a "social substance" which lies at the basis of this value. Nevertheless abstract labor, just as the value which it creates, does not only have a qualitative but also a quantitative side. It has a determined magnitude, in the same sense that the social labor accounted for by the organs of a socialist community has a determined magnitude.
In order to be done with the question of the quantitative determination of abstract labor, we must explain a possible misunderstanding which might arise. At first glance it might seem that if abstract labor is the result of social equalization of labor through the equalization of the products of labor, the only criterion of equality or inequality of two labor expenditures is the fact of equality (or inequality) in the process of exchange. From this standpoint we cannot speak of equality or inequality of two labor expenditures before the moment of their social equalization through the process of exchange. On the other hand, if in the process of exchange these labor expenditures are socially equalized, we must consider them equal even though they are not equal (for example, with respect to the number of hours of labor) in the process of direct production.
Such an assumption leads to false conclusions. It deprives us of the right to say that in the process of exchange equal quantities of labor, and sometimes very unequal quantities (for example, in the exchange of the products of very qualified labor for the products of unqualified labor, or in the exchange of products by their prices of production in a capitalist economy, etc.), are socially equalized. We would have to admit that the social equalization of labor in the process of exchange is carried out in isolation of dependence on quantitative aspects which characterize labor in the process of direct production (for example, the length, intensity, length of training for a given level of qualification, and so on), and thus, the social equalization would lack any regularity since it would be exclusively determined by market spontaneity.
It is easy to show that the theory of abstract labor developed earlier has nothing in common with the false impression mentioned above. We can again return to the example of the socialist community. The organs of the socialist community recognized worker A's right to 20 hours of social labor, and worker B's right to 10 hours of social labor. These calculations would be carried out by the organs of the socialist community on the basis of the properties which characterize the labor in the material-technical process of production (for example, its length, intensity, quantity of produced goods, and so on). If the organs of the socialist community would take as the decisive single criterion, the quantity of physiological energy expended by the workers (we suppose that this quantity can be determined by means of psycho-physiological research) to determine each worker's quantitative share, we would say that the grounds for the social equalization of labor are those properties of labor which characterize it in terms of its physiological and not its material-technical side. But this would not change the problem. In both cases we could say that the act of social equalization of two labor expenditures is carried out on the basis of characteristics which lie outside the act of equalization itself. But from this it does not follow in any sense that the social equality of two labor expenditures, determined on the basis of their physiological equality, is identical with their physiological equality. Even if we assume that a given numerical expression of two quantities of social labor (20 hours and 10 hours of social labor) exactly coincides with the numerical expression of two quantities of physiological energy (20 units and 10 units of physiological energy), there is still an essential difference between the nature of social labor and the expenditure of physiological energy, the social equalization of labor and its physiological equality. This is even more so in those cases when the social equalization is not regulated on the basis of one but on the basis of a whole series of properties which characterize labor in its material-technical or its physiological aspects. In this case, socially - equal labor is not only qualitatively different from physiologically - equal labor, but the quantitative determination of the first can only be understood as the result of social equalization of labor. The qualitative as well as the quantitative characteristics of social labor cannot be grasped without analysis of the social form of the process of production in which the social equalization of labor takes place.
This is precisely the state of affairs which we find in a commodity economy. The equality of two amounts of abstract labor signifies their equality as parts of total social labor - an equality which is only established in the process of social equalization of labor by means of the equalization of the products of labor. Thus we assert that in a commodity economy, the social equality of two labor expenditures or their equality in the form of abstract labor is established through the process of exchange. But this does not prevent us from ascertaining a series of quantitative properties which distinguish labor in terms of its material-technical and its physiological aspects, and which causally influence the quantitative determination of abstract labor before the act of exchange and independent of it. The most important of these properties are: 1) the length of labor expenditure, or the quantity of working time; 2) the intensity of labor; 3)the qualification of labor; and 4) the quantity of products produced in a unit of time. We can briefly examine each of these properties.
Marx considers the quantity of working time expended by the worker the basic property which characterizes the quantitative determination of labor. This method of quantitative determination of labor according to labor-time is characteristic of Marx's sociological method. If we were considering the quantitative determination of labor in a psycho-physiological laboratory, we would have to take as a unit of labor a certain amount of expended physiological energy. But when we consider the distribution of total social labor among individuals and branches of production - a distribution which is carried out consciously in a socialist community and spontaneously in a commodity economy - different quantities of labor appear as different quantities of labor-time. Thus Marx frequently replaces labor with labor-time, and examines labor-time as the substance materialized in the product (Critique, pp. 23, 26).
Thus Marx takes labor-time or "the extensive magnitude of labor" as the basic measure of labor (C., I, p. 519). Together with this property Marx puts the intensity of labor, the "intensive magnitude of labor," i.e., "the quantity of labor expended in a given time," as a supplementary and secondary property (Ibid.). One hour of labor of greater intensity is recognized to be equal, for example, to l 1/2 hours of labor of normal intensity. In other words, the more intensive labor is recognized as equal to longer labor. Intensity is translated into units of labor-time, or intensive magnitude is calculated as extensive magnitude. This reduction of intensity of labor to labor-time strikingly testifies to what extent Marx subordinated the properties characteristic of labor from its physiological aspect under the properties of a social character which play a decisive role in the social process of distribution of labor.
The subordinate role of intensity of labor with respect to labor-time is even more strikingly displayed in Marx's later observations. According to Marx, the property of intensity of labor is taken into consideration to determine a quantity of abstract labor only when the given labor expenditures differ to a lesser or greater extent in comparison with the average level. But "if the intensity of labor were to increase simultaneously and equally in every branch of industry, then the new and higher degree of intensity would become the normal degree for the society, and would therefore cease to be taken account of" (C., I, p. 525).  In other words, if, in a given country, today or fifty years ago, one million working days (eight hours each) are expended for production every day, the sum of values created every day remains unchanged even though the average intensity of labor increases, for example 1 1/2 times, during the half century, and thus the quantity of expended physiological energy increases. This reasoning on Marx's part proves that one cannot confuse physiological with abstract labor, and that the amount of physiological energy cannot be taken as the basic qualitative property which determines the amount of abstract labor and the magnitude of created value. Marx considers labor-time the measure of labor, and the intensity of labor has only a supplementary and subordinate role.
We will devote the next chapter to the problem of qualified labor. Here we will only point out that Marx, faithful to his general view of labor-time as the measure of labor, reduced a day of qualified labor to a given number of days of simple labor, i.e., again to labortime.
Until now we have examined the equalization of amounts of labor expended in various branches of production. If we consider different expenditures of labor in the same branch of production (more precisely, expenditures for the production of goods of the same kind and quality), their equalization is subject to the following principle: two labor expenditures are recognized as equal if they create equal quantities of a given product, even though in fact these labor expenditures can be very different from each other in terms of length of labor-time, intensity, and so on. The working day of a worker who is more highly skilled, or who works with better means of production, is socially equalized with two days of labor of a less qualified worker, or a worker who works with poor means of production, even though the amount of physiological energy expended in the first case would be much smaller than in the second case. Here the decisive property which determines the quantitative characteristicof labor as abstract and socially-necessary does not in any sense represent an amount of expended physiological energy. Here too, Marx reduces the labor of a worker distinguished by his skill, or by better means of production, to socially necessary labor-time, i.e., Marx equalizes labor with a given amount of labor-time.
We can see that the quantitative characteristic of abstract labor is causally conditioned by a series of properties which characterize labor in terms of its material-technical and its physiological sides in the process of direct production, before the process of exchange and independent of it. But if two given labor expenditures, independent of the process of exchange, differ in terms of length, intensity, level of qualification and technical productivity, the social equalization of these labor expenditures is carried out in a commodity economy only through exchange. Socially equalized and abstract labor differ qualitatively and quantitatively from labor which is examined in terms of its material-technical or its physiological aspects.
 Letter of Marx to Engels, August 24, 1867, in Karl Marx and Frederick Engels: Selected Correspondence, Moscow: Progress Publishers, 1965, p. 192.
 A. Bogdanov, Kurs politicheskoi ekonomii (Course of Political Economy), Vol. II, part 4, p. 18.
 Karl Diehl, Sozialwissenschaftliche Erlauterungen zu David Ricardos Grundgesetzen der Volkswirtschaft und Besteurung, Vol. I, Leipzig: F. Meiner, 1921, pp. 102-104.
K. Kautsky, The Economic Doctrines of Karl Marx, London: A. & C.Black, 1925, p. 16.
Otto Gerlach, Uber die Bedingungen wirtschaftlicher Thatigkeit, Jena:G. Fischer, 1890, p. 18.
For example, K. Diehl, Op. Cit., p. 104.
 Leo von Buch, Uber die Elemente der politischen Oekonomie, I Theil: Intensitat der Arbeit, Wert und Preis der Waren, Leipzig: Duncker & Humblot, 1896, p. 149.
 F. Petry, Der soziale Gehalt der Marxschen Werttheorie, Jena, 1916, pp. 23-24.
 An excellent analysis and critique of Petry's book is given in an article by R. Hilferding, in Grunberg's Arhiv fur die Geschichte des Sozialismus und der Arbeiterbewegung, 1919, pp. 439-448. See also our Sovremennye ekonmisty na Zapade (Contemporary Economists in the West), 1927.
 "Teoriya tsennosti i pribyli Marksa pered sudom Fetishista" (Marx's Theory of Value and Profit before the Judgment of Fetishists), Nauchnoye Obozrenie (Scientific Survey), 1898, No. 8, p. 1393.
 See "Otvet kritikam" (Answer to Critics) in I.I. Rubin, Ocherki po teorii stoimosti Marksa (Essays on Marx's Theory of Value), Moskva: Gosudarstvennoe Izdatel'stvo, 1928, which was appended to the third edition.
 Wages, Price and Profit, in Karl Marx and Frederick Engels, Selected Works in Two Volumes, Moscow: Foreign Languages Publishing House, 1962, Volume I, p. 417.
 "In the particular form of production with which we are dealing, viz., the production of commodities, the specific social character of private labor carried on independently, consists in the equality of every kind of that labor, by virtue of its being human labor, which character, therefore, assumes in the product the form of value. . ." (C., I, p. 74).
 An approximately similar view can be found in the article of I. Dashkovski, "Abstraktnyi trud i ekonomicheskie kategorii Marksa" (Abstract Labor and Marx's Economic Categories), Pod znamenem marksizma (Under the Banner of Marxism), 1926, No. 6. Dashkovski also confuses abstract labor with physiological labor. (See Rubin, "Otvet kritikam," Loc. Cit.)
"We now see, that the difference between labor, considered on the one hand as producing utilities, and on the other hand, as creating value, a difference which we discovered by our analysis of a commodity, resolves itself into a distinction between two aspects of the process of production" (C.,I,p. 197), i.e., between the process of production in its technical aspect and its social aspect. See F. Petry, Der soziale Gehalt der Marxschen Werttheorie, Jena, 1916, p. 22.
 Marx wrote, "specific" (osobennyi) (Besonderheit), i.e., the concrete character of labor (Critique, p. 29). Translators often create confusion by translating the term "besondere" (i.e., specific or concrete) with the word "private."
 In the Critique, Marx calls abstract labor "universal," as we mentionedearlier.
K. Marx "Introduction to the Critique of Political Economy," in A Contribution to the Critique of Political Economy, Chicago: Charles Kerr,1904, pp. 299-300. Also see Rubin, "Otvet kritikam," Loc. Cit.
See above, in Chapter Twelve, the citations in which Marx recognizes socially equalized labor as the substance of value.
In the first German edition of Capital, Marx summarized the difference between concrete and abstract labor as follows: "From what has been said it follows that a commodity does not possess two different forms of laborbut one and the same labor is defined in different and even opposed ways depending on whether it is related to the use value of commodities as to its product, or to commodity value as to its material expression" (Kapital, I, 1867, p. 13. Marx's italics). Value is not the product of labor but is a material, fetish expression of the working activity of people. Unfortunately in the second edition Marx replaced this summary which underlines the social character of social labor by the well-known concluding sentence of section two of Chapter I which has given many commentators a basis for understanding abstract labor in a physiological sense: "all labor is, speaking physiologically, an expenditure of human labor-power" (C., I, p. 46). It seems that Marx himself knew the inaccuracy of the preliminary characterization of abstract labor which he gave in the second edition of Capital. Striking proof of this is the fact that in the French edition of Volume I of Capital (1875), Marx felt it necessary to complete this characterization: here, on page 18, Marx simultaneously gave both definitions of abstract labor; first of all he repeats the above cited definition from the first edition of Capital, after which follows the definition of the second edition. It must not be forgotten that as a general rule, in the French edition of Capital, Marx simplified and in places shortened his exposition. However, on this given point he felt it necessary to supplement and complicate the characterization of abstract labor, thus recognizing, it would seem, the inadequacy of the definition of abstract labor given in the second edition.
 See Rubin's "Otvet kritikam," Loc. Cit.
 This is why Stolzmann is wrong. He writes: "If the meaning and character of all economic events follows from their 'social functions,' why is this not true of labor as well, why does labor not find its character in its social function, i.e., in the function which belongs to it within the present economic order which is the subject to be explained?" (Stolzmann, Der Zweck in der Volkswirtschaft, 1909, p. 533). Actually the labor which creates value was not viewed by Marx as a technical factor of production, but from the point of view of the social forms of its organization. According to Marx, the social form of labor does not hang in a vacuum: it is closely related to the material process of production. Only through a complete misinterpretation of the social form of labor in Marx's system is it possible to assert that 'Saber for Marx is simply a technical factor of production" (S. Prokopovich, K kritike Marksa (Towards a Critique of Marx), 1901, p. 16), or to consider it "a fundamental error of Marx that in explaining value in terms of labor he neglects the different evaluations of different forms of labor" as a factor of production (G. Cassel, "Grundriss einer elementaren Preislehre," Zeitschrift fur die gesamte Staatswissenschaft, 1899, No. 3, p. 447). Even Marshall sees Marx's error in his having ignored the "quality of labor" (Marshall, Principles of Economics, 1910, p. 503). The question is whether we are interested in the social or the technical properties of labor. Marx was interested in the social forms or social quality of labor in a commodity economy, a form which is expressed in the act of abstraction from the technical properties of different forms of labor.
Marx expressed the same idea more sharply in Theorien uber denMehrwert, III, pp. 365-366: "If this intensification of labor would become general, the value of commodities would then have to fall consistently with the smaller amount of labor-time expended on them." If, with a general increase of intensity of labor, 12 hours are expended instead of an earlier 15 hours on a given product, then in Marx's view the value of the product falls (since it is determined by labor-time and by the number of expended hours). The amount of physiological energy expended on the products has not changed (i.e., in 12 hours just as much energy is expended now as was expended in 15 hours earlier). Thus from the point of view of the advocates of a physiological interpretation of labor value, the value of the product would have to remain unchanged.