If the contradiction in motion, instinctive urge, and the like, is masked for ordinary thinking, in the simplicity of these determinations, contradiction is, on the other hand, immediately represented in the determinations of relationship. The most trivial examples of above and below, right and left, father and son, and so on ad infinitum, all contain opposition in each term. That is above, which is not below; ‘above’ is specifically just this, not to be ‘below’, and only is, in so far as there is a ‘below’; and conversely, each determination implies its opposite. Father is the other of son, and son the other of father, and each only is as this other of the other; and at the same time, the one determination only is, in relation to the other; their being is a single subsistence. The father also has an existence of his own apart from the son-relationship; but then he is not father but simply man; just as above and below, right and left, are each also a reflection-into-self and are something apart from their relationship, but then only places in general. Opposites, therefore, contain contradiction in so far as they are, in the same respect, negatively related to one another or sublate each other and are indifferent to one another. Ordinary thinking when it passes over to the moment of the indifference of the determinations, forgets their negative unity and so retains them merely as ‘differents’ in general, in which determination right is no longer right, nor left left, etc. But since it has, in fact, right and left before it, these determinations are before it as self-negating, the one being in the other, and each in this unity being not self-negating but indifferently for itself.
Therefore though ordinary thinking everywhere has contradiction for its content, it does not become aware of it, but remains an external reflection which passes from likeness to unlikeness, or from the negative relation to the reflection-into-self, of the distinct sides. It holds these two determinations over against one another and has in mind only them, but not their transition, which is the essential point and which contains the contradiction. Intelligent reflection, to mention this here, consists, on the contrary, in grasping and asserting contradiction. …Only when the manifold terms have been driven to the point of contradiction do they become active and lively towards one another, receiving in contradiction the negativity which is the indwelling pulsation of self-movement and spontaneous activity. …when the difference of reality is taken into account, it develops from difference into opposition, and from this into contradiction…Ordinary…thinking, which abhors contradiction, as nature abhors a vacuum, rejects this conclusion…
G.W.F.Hegel, Hegel’s Science of Logic, Trans., A.V.Miller, Humanities Press, New York, 1976, pp. 441-442