The discussions of every age are filled with the issues on which its leading schools of thought differ. But the general intellectual atmosphere of the time is always determined by the views on which the opposing schools agree. They become the unspoken presuppositions of all thought, and common and unquestioningly accepted foundations on which all discussion proceeds.
When we no longer share these implicit assumptions of ages long past, it is comparatively easy to recognize them. But it is different with regard to the ideas underlying the thought of more recent times. Here we are frequently not yet aware of the common features which the opposing systems of thought shared, ideas which for that very reason often have crept in almost unnoticed and have achieved their dominance without serious examination. This can be very important because, as Bernard Bosanquet once pointed out, ``extremes of thought may meet in error as well as in truth.''17.1 Such errors sometimes become dogmas merely because they were accepted by the different groups who quarreled on all the live issues, and may even continue to provide the tacit foundations of thought when most of the theories are forgotten which divided the thinkers to whom we owe that legacy.
When this is the case, the history of ideas becomes a subject of eminently practical importance. It can help us to become aware of much that governs our own thought without our explicitly knowing it. It may serve the purposes of a psychoanalytical operation by bringing to the surface unconscious elements which determine our reasoning, and perhaps assist us to purge our minds from influences which seriously mislead us on questions of our own day.
My purpose is to suggest that we are in such a position. My thesis will be that in the field of social thought not only the second half of the nineteenth century but also our own age owes much of its characteristic approach to the agreement between two thinkers who are commonly regarded as complete intellectual antipodes: the German ``idealist'' Georg Wilhelm Friedrich Hegel and the French ``positivist'' Auguste Comte. In some respects these two men do indeed represent such complete extremes of philosophical thought that they seem to belong to different ages and scarcely even to talk about the same problems. But my concern here will be only incidentally with their philosophical systems as a whole. It will be chiefly with their influence on social theory. It is in this field that the influence of philosophical ideas can be most profound and most lasting. And there is, perhaps, no better illustration of the far-reaching effects of the most abstract ideas than the one I intend to discuss.