In this essay, I shall attempt to clarify somewhat a question discussed in my interview with *New Left Review*footnote^{1}—although one that is very difficult to deal with briefly: the problem of the difference between ‘real opposition’ (Kant’s *Realopposition* or *Realrepugnanz*) and ‘dialectical contradiction’. Both are instances of opposition, but they are radically distinct in kind. ‘Real opposition’ (or ‘contrariety’ of incompatible opposites) is an opposition ‘without contradiction’ (*ohne Widerspruch*). It does not violate the principles of identity and (non)-contradiction, and hence is compatible with formal logic. The second form of opposition, on the contrary, is ‘contradictory’ (*durch den Widerspruch*) and gives rise to a dialectical opposition. Marxists, as we shall see, have never entertained clear ideas on this subject. In the overwhelming majority of cases they have not even suspected that there were *two* oppositions and that they were radically different in nature. In the rare cases where this fact has been noted, its significance has been misunderstood, and ‘real opposition’ has also been considered as

*‘Contradictory’ or Dialectical Opposition*

This is traditionally expressed by the formula ‘a not-a’. It is the instance in which one opposite cannot stand without the other and vice-versa (mutual attraction of opposites). Not-a is the negation of a. In itself and for itself it is nothing; it is the negation of the other *and nothing else*. Therefore if we wish to attach any significance to not-a, we must at the same time know what a is, i.e. what not-a is negating. But a, too, is negative. Just as not-a is its negation, so a is the negation of not-a. Thus since to say a is in effect equivalent to saying not-not-a, a too, if it is to have any meaning, must be referred to the element of which it is the negation. Neither of the two poles is anything in itself or for itself; each is a *negative*. Furthermore, each is a negative-*relation*. If in fact we wish to know what one extreme is, we must at the same time know what the other is, which the first element is negating. Each term therefore, to be itself, implies a relation to the other term; the result is unity (the unity of opposites). Only *within* this unity is each term the negation of the other.

The origins of this dialectic go back to Plato. Both opposites are *negatives*, in the sense that they are un-real, non-things (*Undinge*)—they are *ideas*. ‘The notion of true dialectic’, says Hegel in reference to Plato, ‘is to demonstrate the necessary movement of pure notions, without thereby resolving these into nothing, for the result, simply expressed, is that they are this movement, and the universal is just the unity of these opposite notions’.footnote^{2}

A movement of *pure notions*, then, interpenetrating each other. One passes into the other, and this latter into the first. In fact each is simply the *Negative* of the other. In itself it is nothing. Its essence lies outside it, in its opposite. To be itself, then, and to give meaning to its own *Negative*, it has to be referred to the nature of the other of which it is the negation. In other words, this is an *inclusive* opposition. Here, in a nutshell, we have all the key-concepts of the Platonic dialectic: the *symploke eidon*footnote^{3}, i.e. the mutual connection or implication of ideas; the *koinonia ton genon,* i.e. the community of supreme classes; the *megista gene*, or in Hegel’s terminology the ‘pure concepts’. Here, too, we have the problem of the *diairesis*, or division into species.footnote^{4}