It is likely that the emphasis upon the metaphysical and epistemological implications of the sociology of knowledge can be traced, in part, to the fact that the first proponents of this discipline stemmed largely from philosophical rather than scientific circles. The burden of further research is to turn from this welter of conflicting opinion to empirical investigations which may establish in adequate detail the uniformities pertaining to the appearance, acceptance and diffusion, or rejection and repression, development and consequences of knowledge and ideas.

The last two decades have witnessed, especially in Germany and France, the rise of a new discipline, the sociology of knowledge (Wissenssoziologie), with a rapidly increasing number of students and a growing literature (even a “selected bibliography” would include several hundred titles). Since most of the investigations in this field have been concerned with the socio-cultural factors influencing the development of beliefs and opinion rather than of positive knowledge, the term. “Wissen” must be interpreted very broadly indeed, as referring to social ideas and thought generally, and not to the physical sciences, except where expressly indicated.

A theory of knowledge is an answer to the question "What is knowledge?" This question, like many which are asked by philosophers, sounds very simple. We all know, at least roughly, what knowledge is. But difficulties appear the moment that we begin to fill in the details.

The sociology of knowledge showed, two generations ago, how major world-views are based on the interests and experiences of major social groups. Research on the sociology of science, giving fascinating glimpses of laboratory life and prestige hierarchies among scientists, has revealed the social relations underpinning knowledge in the natural sciences. The point is reinforced by Michel Foucault's celebrated researches on 'power-knowlege', the intimate interweaving of new sciences (such as medicine, criminology, and sexology) with new institutions and forms of social control (clinics, prisons, factories, psychotherapy).

The basic contentions of the argument of this book are implicit in its title and sub-title, namely, that reality is socially constructed and that the sociology of knowledge must analyse the process in which this occurs.

The purpose of this book is, firstly, to make a rapid survey, the barest outline, of the knowledge which has existed, all through the history of man, and guided his development from behind the scenes; and, secondly, to study how, upon the foundations of that knowledge there can be built an entirely new way of life, which would produce the final pattern of a sane and successful world civilization.

Theoretical knowledge is only a small and by no means the most important part of what passed for knowledge in a society… the primary knowledge about the institutional order is knowledge... is the sum total of ‘what everybody knows’ about a social world, an assemblage of maxims, morals, proverbial nuggets of wisdom, values and beliefs, myths, and so forth.

Knowledge is the appropriate collection of information, such that it's intent is to be useful. Knowledge is a deterministic process. When someone "memorizes" information (as less-aspiring test-bound students often do), then they have amassed knowledge. This knowledge has useful meaning to them, but it does not provide for, in and of itself, an integration such as would infer further knowledge.

A modern theory of knowledge which takes account of the relational as distinct from the merely relative character of all historical knowledge must start with the assumption that there are spheres of thought in which it is impossible to conceive of absolute truth existing independently of the values and position of the subject and unrelated to the social context. Even a god could not formulate a proposition on historical subjects like 2 x 2 = 4, for what is intelligible in history can be formulated only with reference to problems and conceptual constructions which themselves arise in the flux of historical experience.

What is knowledge? Ever since class society came into being the world has had only two kinds of knowledge, knowledge of the struggle of production and knowledge of the class struggle. Natural science and social science are the crystallization of these two kinds of knowledge, and philosophy is the generalization and summation of the knowledge of nature.

Knowledge can be considered as a collection of information, or as an activity, or as a potential. If we think of it as a collection of information, then the analogy of a computer's memory is helpful, for we can say that knowledge about something is like the storage of meaningful and true strings of symbols in a computer.

Thus then does the Doctrine of Knowledge, which in its substance is the realisation of the absolute Power of intelligising which has now been defined, end with the recognition of itself as a mere Schema in a Doctrine of Wisdom, although indeed a necessary and indispensable means to such a Doctrine: — a Schema, the sole aim of which is, with the knowledge thus acquired, — by which knowledge alone a Will, clear and intelligible to itself and reposing upon itself without wavering or perplexity, is possible, — to return wholly into Actual Life; — not into the Life of blind and irrational Instinct which we have laid bare in all its nothingness, but into the Divine Life which shall become visible to us.

Knowledge is the product of leisure. The members of a very primitive society have no time to amass knowledge; their days are fully occupied with the provision of the bare necessities of life. But as soon as a community begins to accumulate wealth, and so becomes able to support a leisured class (priests, instructors of rich men's children), an opportunity is created for those who desire knowledge to devote their lives to its acquirement. Out of this 'curiosity to know' science is born.

Since it cannot be overlooked by the Doctrine of Knowledge that Actual Knowledge does by no means present itself as a Unity, such as is assumed above but as a multiplicity, there is consequently a second task imposed upon it, — that of setting forth the ground of this apparent Multiplicity. It is of course understood that this ground is not to be derived from any outward source, but must be shown to be contained in the essential Nature of Knowledge itself as such; — and that therefore this problem, although apparently two-fold, is yet but one and the same, — namely, to set forth the essential Nature of Knowledge.