Popper on Utilizing Knowledge: Piecemeal Social Engineering, Technological Warnings and Social Planning


Herzl Baruch


The question of utilizing knowledge undergoes a change in Popper’s thought. It starts with the notion that utilizing knowledge must be grounded on scientific theory alone (The Open Society and its Enemies, The Poverty of Historicism). It ends with the notion that utilizing knowledge can also be grounded on practical theory (Knowledge and the Body-Mind Problem).

In his books The Open Society and The Poverty of Historicism, Popper contends that exercising a scientific theory is permissible, provided that when it is refuted, it is possible to go back to the previous traditional policy. The new policy, which is based on a scientific theory that has withstood the test of refutation, is called “piecemeal social engineering” (The Open Society, vol.1, 162-163; The Poverty of Historicism, 58-59). It is reformist and cautious, unlike the comprehensive and revolutionary social engineering, as historicism maintains. To the historicist, “real sociological laws are historical laws” and it leads him to the idea of ‘large-scale forecasts’ or to the kind of prediction Popper calls ‘prophecy’ (The Poverty of Historicism, 42-43). Popper precludes the feasibility of wide scale social engineering. Opposed to prophecy “are predictions of the second kind which we can describe as technological predictions since predictions of this kind form a basis of engineering” (ibid., 43). Therefore, ” The characteristic approach of the piecemeal engineer is this. Even though he may perhaps cherish some ideals which concern society ‘as a whole’ – its general welfare, perhaps, he does not believe in the method of re-designing it as a whole. Whatever his ends, he tries to achieve them by small adjustments and re-adjustments which can be continually improved upon” (ibid., 66).

If the criticism of historicism allows the conclusion that only a refutable social theory can form a basis for piecemeal social engineering, then in Conjectures and Refutations Popper claims that a social theory can only establish “technological warnings”. Technological warnings are guidelines as to what is not to be done. Here he presents “the view that the task of the theoretical social sciences is to discover the unintended consequences of our actions” and this “brings these sciences very close to experimental natural sciences” (Conjectures and Refutations, 342-343). One of the examples that he uses in order to explicate a technological warning is the following: “You cannot, without increasing productivity, raise the real income of the working population” (ibid., 343). The common ground for both piecemeal social engineering and technological warnings is scientific theory, whether it is successful in withstanding the refutation tests (as in leading theories in natural sciences) or if “its hypotheses are promising” (as in the liberal economic theory in social sciences). But since it not the task of the theoretical social theories to guide us as to what is to be done, whose task is it? It will be suggested that social piecemeal engineering could be based either on a refutable theory from the natural sciences or on a practical theory (as will be explained bellow).

While in his earlier books, it seemed that piecemeal social engineering and technological warnings could be grounded on scientific theory alone, in Knowledge and the Body-Mind Problem Popper suggests that social planning, not necessarily only social engineering, can be based upon “practical” theory as well. What the practical and scientific fields have in common in terms of advancement in knowledge is that the starting point for both is a state of problem (P1). Then a tentative theory (TT) to the solution for the problem is offered, followed by putting this theory to the test in the form of trial and error elimination (EE). Finally, a new problem arises, which has to be dealt with (P2) (Knowledge and the Body-Mind Problem, 10-11). The example he uses in order to explicate how practical knowledge advances and utilized is this: “Henry Ford’s original problem was: how can we provide transport for the vast spaces of the United States? This was his P1. He proposed a theory: by building a cheap motorcar. This led through various trials and errors to a new problem: how can we provide the roads and parking places needed for our cars? The original problem P1 was the problem of transport. The new problem P2 is the traffic problem – a problem of frustration” (ibid., 11). It will be claimed that this scheme for the advancement and utilization of knowledge should also be applied to ordinary citizens.

In this essay, I shall attempt to answer the following questions: (a) How is the utilization of scientific based knowledge and practical based knowledge issue to be settled? (b) What are the implications of the knowledge utilization question for different levels of refutation tests and error elimination that Popper adopts? And (c) what is the connection between utilizing knowledge and the existing traditional institutional policy?


Popper, K. R., The Poverty of Historicism, Routledge, 1957.

Popper, K. R., The Open Society and Its Enemies, V. 1, Routledge, 1966.

Popper, K. R., Conjectures and Refutations, Routledge, 1972.

Popper, K. R., Knowledge and the Body-Mind Problem, Routledge, 1994.