Friedrich August von Hayek and Walter B. Weimer, Weimer–Hayek Discussion (1982)

This conference discussion brings Hayek and Weimer into dialogue with psychologists and audience members about The Sensory Order, the explanation of complex phenomena, and the relationship between neural organization and market coordination. Its question-and-answer structure moves from complexity and psychological terminology through scientific methodology to economic knowledge, mathematical modelling, and tradition. The governing claim is that complex orders can be understood without their particular outcomes being exhaustively predicted: explanation concerns organizing principles and patterns, while coordinated activity draws on information unavailable to any single observer.

Hayek initially treats the difference between simple and complex phenomena as one of degree, measured by the number of variables an explanatory theory must contain. Biology and competitive markets demand models with many interacting variables; reducing them to artificially restricted situations risks losing what needs explanation. Perception likewise involves hierarchies of coordinated classificatory structures, rather than a single level of processing. Hayek recalls discovering an affinity with von Neumann’s work on automata, but describes this as a convergence of independently developed approaches, not a source from which he derived his psychology.

A central exchange concerns whether Hayek’s associationistic vocabulary commits him to particular theories of learning. Weimer argues that the terminology available when Hayek wrote can be replaced without sacrificing the theory’s content. Hayek supports this interpretation by distinguishing the book’s statement of its problem, its provisional physiological mechanisms, and its philosophical consequences:

But I think that the theme was not to provide a true explanation, but to show what an account would need to look like to be an explanation.

The distinction makes The Sensory Order a specification of explanatory requirements rather than an endorsement of one neurophysiological model. Yet this does not make every concept dispensable. Weimer retains contiguity as a spatial-temporal relation while separating it from contiguity understood as an associationist learning mechanism. His account of sensation similarly locates experience within the inherited organization of the nervous system: memory does not merely interpret already constituted sensations, but helps make sensation possible.

The discussion tests this framework against the objection that a classificatory system unable fully to comprehend itself would make psychology impossible. Weimer answers by distinguishing explanation of principle from explanation of particular events. Hayek develops the distinction as a limitation on prediction, not a denial of science:

The more complex the phenomena, the more our predictions are in this sense limited to very general statements—as, for example, are the type of statements in the theory of evolution.

“Pattern prediction” identifies the character of a structure without specifying each occurrence within it. Psychology remains possible, but cannot promise the precisely situated predictions associated here with physical science. The clinical exchange preserves this restraint: Hayek claims no developed application to psychopathology, while Pribram suggests that pathological patterns might be predictable without prediction of individual situations.

Hayek’s methodological allegiance is chiefly Popperian. He recalls resisting Marxist and Freudian claims to irrefutability and accepting refutability as a condition of scientific status. Nevertheless, he acknowledges complications introduced by Kuhn, Lakatos, and Feyerabend, and remains unconvinced by some of Popper’s later epistemology. Weimer’s separate intervention on causality rejects the traditional combination of linear interaction and microdeterminism as an adequate description of hierarchical nervous organization. These exchanges qualify the discussion’s common ground: it offers neither a settled reconciliation of philosophies of science nor a general rejection of explanation.

The strongest bridge between psychology and economics is the utilization of dispersed knowledge:

In both cases we have complex phenomena in which there is a need for a method of utilizing widely dispersed knowledge.

Neurons, buyers, and sellers contribute to a system without knowing all the purposes their activity serves. In markets, prices communicate locally relevant information without transmitting the particular circumstances behind it. Central planning fails on this account because knowledge includes not only existing facts but also what individuals can discover when circumstances make discovery useful. Hayek consequently treats prices as prospective guides to action, contrasting this function with accounts that explain them through past expenditures of labour or resources.

His criticism of quantitative economics follows from the same epistemic argument, rather than from hostility to mathematics:

Mathematical economists do not understand that the great advantage of mathematics is that it permits us to describe patterns without requiring that we know their quantitative mechanisms.

Topology exemplifies the abstract mathematics he values. Equations can characterize an order without supplying all its changing data; mistaking that characterization for an achievable numerical specification creates false expectations of prediction. Hayek doubts that complex systems reach equilibrium and endorses a process-oriented economics. The hierarchy–heterarchy question remains only partly answered: he allows hierarchies to establish and enforce abstract market rules, but does not supply the requested general account connecting distributed and hierarchical organization.

The closing exchange extends dispersed knowledge to habits, customs, and inherited practices:

So useful functions are often outside our understanding.

Tradition can preserve practical knowledge that its participants cannot articulate. Hayek therefore denies that inability to explain a practice is itself sufficient reason to reject it, while leaving room for theoretical demonstration of its ineffectiveness. The discussion’s significance lies in connecting limits of explicit knowledge across psychology, economics, and cultural evolution. Its conceptual distinction is between understanding how an order works and possessing the information necessary to reconstruct or direct all its particulars.