I shall start with an immediate reading, and here I let Marx speak for himself.
In a letter to Engels on 24 August 1867 (MECW 42, p. 407) he writes:
The best points in my book are: 1. (this is fundamental to all understanding of the FACTS) the two-fold character of labour according to whether it is expressed in use-value or exchange-value, which is brought out in the very First Chapter; 2. the treatment of surplus-value regardless of its particular forms as profit, interest, ground rent, etc. This will be made clear in the second volume especially. The treatment of the particular forms in classical political economy, which they are for ever being jumbled up together with the general form, is an olla potrida [a regular hash].
In the Notes on Adolf Wagner’s ‘Lehrbuch der politischen Ökonomie’, written in 1883, at the end of his life, Marx says of Wagner (MECW 24, p. 546):
the vir obscurus [Wagner] has overlooked the fact that even in my analysis of the commodity I do not come to a halt with its dual way of presenting itself, but immediately proceed to show that in this duality of the commodity there presents itself the dual character of the labour whose product it is: of useful labour, i.e., the concrete modes of the labours which create use-values, and of abstract labour, of labour as expenditure of labour-power, regardless of the ‘useful’ way in which it is expended (on which the presentation of the production process depends); that in the development of the value-form of the commodity, in the final instance its money-form, and thus of money, the value of a commodity presents itself in the use-value of the other commodity, i.e., in its natural form; that surplus-value itself is derived from a ‘specific’ use-value of labour-power belonging to it exclusively, etc., etc.; that, in other words, for me use-value plays an important part quite different from its part economics hitherto, but nota bene it still only comes into consideration when such a consideration stems from the analysis with regard to economic formations, not from arguing hither and thither about the concepts or words ‘use-value’ and ‘value’.
I quote these texts as protocols in which Marx expressly designates the basic concepts that govern his whole analysis. In these texts, therefore, Marx indicates the differences between him and his predecessors. In this way he gives us the specific difference of his object – but, note, less in the form of the concept of his object than in the form of concepts assisting in the analysis of that object.
These texts are far from being the only ones in which Marx announces his discoveries. We find far-reaching discoveries designated all the way through a reading of Capital: e.g., the genesis of money, which the whole of classical economics did not manage to think; the organic composition of capital (c + v), absent from Smith and Ricardo; the general law of capitalist accumulation; the law of the tendency of the rate of profit to fall; the theory of ground-rent, etc. I shall not list all these discoveries, each of which makes intelligible economic facts and practices which the Classical Economists either passed over in silence or evaded because they were incompatible with their premises. In fact, these detailed discoveries are merely the immediate or distant consequences of the new basic concepts that Marx identified in his work as his master discoveries. Let us examine them.
The reduction of the different forms of profit, rent and interest to surplus-value is itself a discovery secondary to that of surplus-value. The basic discoveries therefore concern:
(1) the value/use-value opposition; the reference of this opposition to another opposition which the Economists were not able to identify: the opposition abstract labour/concrete labour; the particular importance which Marx, as opposed to the Classical Economists, attributes to use-value and its correlate concrete labour; the reference to the strategic points where use-value and concrete labour play a decisive part: the distinctions between constant capital and variable capital on the one hand, and between the two departments of production on the other (Department I, production of means of production; Department II, production of means of consumption).
(2) surplus-value.
To sum up: the concepts which contain Marx’s basic discoveries are: the concepts of value and use-value; of abstract labour and concrete labour; and of surplus-value.
That is what Marx tells us. And there is no apparent reason why we should not take him at his word. In fact, while reading Capital we can prove that his economic analyses do depend on these basic concepts in the last instance. We can, so long as our reading is a careful one. But this proof is not self-evident. It presupposes a great struggle for rigour – and above all it necessarily implies from the beginning something which is present in Marx’s declared discoveries – but present in a strange absence – if we are to complete this proof and see clearly in the very clarity it produces.
As an index which gives a negative foretaste of this absence, one comment will do: the concepts to which Marx expressly relates his discovery and which underlie all his economic analysis, the concepts of value and surplus-value, are precisely the concepts on which all the criticism addressed to Marx by modern economists has focused. It is not immaterial to know in what terms these concepts have been attacked by non-Marxist economists. Marx has been criticized on the grounds that they are concepts which, although they make allusion to economic reality, remain at heart non-economic, ‘philosophical’ and ‘metaphysical’ concepts. Even as enlightened an economist as Conrad Schmidt – who was intelligent enough to deduce the law of the tendency of the rate of profit to fall from Volume Two of Capital soon after its publication, even though that law was first expounded in Volume Three – even Conrad Schmidt attacked Marx’s law of value as a ‘theoretical fiction’, a necessary one no doubt, but a fiction all the same. I do not quote these criticisms for fun, but because they are directed at the very foundation of Marx’s economic analyses, the concepts of value and surplus-value, which are rejected as ‘non-operational’ concepts designating realities which are noneconomic because they are non-measurable, non-quantifiable. Obviously, this reproach in its own way betrays the conception the economists in question have of their own object, and of the concepts it authorizes; but if this reproach does show us the point in which their opposition to Marx is at its most palpable, these economists do not give us Marx’s object in their reproach, precisely because they treat that object as ‘metaphysical’. However, I indicate this point as the point of misunderstanding, the point where the Economists misconstrue Marx’s analyses. But this misunderstanding in their reading was only possible because of a misunderstanding of Marx’s object itself: a misunderstanding that made the Economists read their own object into Marx, instead of reading another object in Marx which is not their own object but a quite different one. This point of misunderstanding which the Economists declare the point of Marx’s theoretical weakness and error is, on the contrary, the point at which he is strongest! the point which marks him off radically from his critics, and also, on occasion, from some of his closest followers.
To demonstrate the extent of this misunderstanding, I should like to quote the letter from Engels to Conrad Schmidt (12 March 1895) from which we took the echo of Schmidt’s objection above. Engels replies as follows:
[In your objections] I find lapsing into detail … and for this I put the blame on the eclectic method of philosophizing endemic at German universities since 1848, a method which sight of the whole, and all too often goes astray by indulging in almost endless and unprofitable speculation on minutiae. Now it so happens that your earlier studies of classical philosophy revolved primarily around Kant, and Kant … was more or less compelled … to make what appeared to be formal concessions … to Wolfian speculation. It is thus I explain your tendency, also apparent in your epistolatory digression on the law of value, to be engrossed in minutiae … which is why you reduce the law of value to a fiction, a necessary fiction, in much the same way as Kant reduced the existence of God to a postulate of practical reason.
Your objections to the law of value apply to all concepts regarded from the standpoint of reality. The identity of thinking and being, to use a Hegelian expression, corresponds in all respects to your example of the circle and the polygon. In other words, the concept of an object and its reality run side by side like two asymptotes which, though constantly converging, will never meet. This difference between the two is the self-same difference which is responsible for the fact that the concept is not immediately and ipso facto reality and reality is not immediately its own concept. Because a concept is by its essentially a concept, hence does not ipso facto and prima facie coincide to the reality from which it has had first be abstracted, that concept is always something more than a fiction, unless you declare all reasoned conclusions to be fictive on the grounds that they correspond to reality only in a very circuitous way, and even then only approximately, like converging asymptotes (MECW 50, pp. 463–4).
This reply is astounding (despite the banality of its obviousnesses) and it constitutes a kind of well-intentioned commentary on the misunderstanding, on which Marx’s opponents set out to produce ill-intentioned commentaries. Engels escapes Conrad Schmidt’s ‘operational’ objection with a theory of knowledge made to order – that looks to the approximations of abstraction to establish the inadequacy of the concept as a concept to its object! This answer is beside the point: for Marx the concept of the law of value is in fact a concept perfectly adequate to its object, since it is the concept of the limits of its variation, and therefore the adequate concept of the field of its inadequacy – and in no sense an inadequate concept by virtue of some original sin which affects all concepts brought into the world by human abstraction. Engels therefore transfers to an empiricist theory of knowledge, as a native weakness of the concept, precisely what constitutes the theoretical strength of Marx’s adequate concept! This transfer is only possible with the complicity of this ideological theory of knowledge, ideological not only in its content (empiricism), but also in its use, since it is designed to answer, among other things, precisely this theoretical misunderstanding. There is a risk not only that the theory of Capital will be affected by it (Engels’s thesis in the Preface to Volume Three: the law of value is economically valid ‘from the beginning of exchange … until the fifteenth century A.D.’ is a disturbing example), but also that Marxist philosophical theory will be marked, and with what a mark! The mark of the empiricist theory of knowledge which serves as a silent theoretical norm both in Schmidt’s objection and in Engels’s reply. I have dwelt on this reply in order to stress the fact that the present misunderstanding may betray not only political or ideological ill-will, but also the effects of a theoretical blindness which is a serious hazard so long as we neglect to pose Marx the question of his object.