Friedrich August von Hayek, The Sensory Order After 25 Years (1982)

Hayek’s conference contribution, published as chapter 13 of Cognition and the Symbolic Processes, volume 2, revisits the origins, explanatory machinery, and philosophical implications of The Sensory Order (1952). Its movement is autobiographical before becoming theoretical: Hayek reconstructs his early encounter with physiological psychology, reformulates his account of neural classification through the concept of disposition, and closes by considering the limits of explanation. The central claim is that mental qualities arise from relations among neural events, not from intrinsic qualities carried by individual sensory impulses. A physiological explanation of this organization is possible in principle, but it does not entail that the human mind can fully explain itself or predict another organism’s conduct.

Hayek traces his initial insight to reading Ernst Mach after returning from World War I. Mach’s account of experience-dependent organization suggested a more radical possibility: the supposedly pure sensation underlying that organization might be unnecessary. Qualities could instead depend entirely on an impulse’s position within a system of connections.

I began to see that there were two orders in which we could conceive of the same set of events—two orders that were in some respects similar but yet differed in exactly that way in which our sensory picture of the world and our scientific conception of it differed from each other.

The distinction is between classifications of events, rather than between two independent substances. Sensory experience supplies an imperfect map whose units belong to the mental order, while physical science reclassifies events to explain regularities that sensory categories obscure. Mental events themselves remain physical events within an organism, organized so as to relate that organism to its surroundings and support survival. Hayek initially concentrated on sensory qualities because their ordering offered a tractable demonstration of a theory intended eventually to encompass emotions, concepts, images, and drives.

The autobiographical account explains both the theory’s early formation and its delayed publication. Its basic idea was written down by 1920, but Hayek’s professional commitment to economics interrupted sustained psychological work. Returning to the manuscript around 1946, he found accumulated factual knowledge without, in his judgment, a corresponding resolution of the theoretical problem. His criticism of “scientism” had meanwhile clarified what explanation could accomplish in complex domains. Although he understood mental attributes through their effects as guides to action, he rejected behaviorism’s reduction of the inquiry to observable conduct: behavior was the outcome of an internal process requiring reconstruction.

That reconstruction treats the nervous system as continuous, simultaneous classification and reclassification at many levels. Revisiting his book, Hayek now regards “disposition” as the term that could have made its exposition clearer. Dispositions include readiness to interpret stimuli, alter other dispositions, and initiate long sequences whose eventual actions may remain merely potential. His retrospective clarification therefore shifts attention from discrete responses to the changing organization of possibilities within the system.

Indeed my “linkages” were assumed to create or determine the content of those mental events on which associations were supposed to operate.

This distinction separates physiological linkages from associations between already constituted mental contents. Connections established through earlier simultaneous occurrences help determine what an impulse means by determining its possible consequences. Each impulse evokes a “following”; overlapping followings can summate sufficiently to make other neurons fire. Hayek cautions that a diagram of these ramifications might misleadingly suggest local groupings, whereas the connections can extend across the cortex and interlace extensively. Nor does the dispersion of impulses necessarily produce ever-increasing excitation: patterns may persist through recurrent activity.

Stimuli and responses thus become merely the input and output of an ongoing process in which the state of the organism constantly changes from one set of dispositions to interpret and respond to what is acting upon it and in it, to another such set of dispositions.

The organism is consequently active before any particular stimulus arrives. New inputs redirect an existing flow according to the system’s current dispositions. Hayek’s analogy with a stock of capital emphasizes this accumulated organization: inputs sustain a structure yielding continuous outputs, although the neural “capital,” unlike economic capital, is not used up. Meaning resides in the place and consequences of an event within this organized process, not in an isolated impulse.

The final section distinguishes this explanatory approach from the ambition of complete reduction. Physics seeks a classification better suited to explaining relations among events; psychology asks why those events produce a different ordering in sensory experience. Hayek maintains that their relationship can be explained in principle without becoming fully transparent to us. Absolute assertions about whether separate worlds “exist” are therefore less useful than specifying what has a definable place in our thought.

The proof I have attempted in my book that any explanation—which always rests on classification—is limited by the fact that any apparatus of classification must be of a higher degree of complexity than what it classifies, and that therefore the human brain can never fully explain itself, may be inadequate.

The qualification matters: Hayek presents a fundamental limit while acknowledging that his proof may not establish it rigorously. His mechanical-rat example distinguishes knowledge of a mechanism from prediction of its particular actions. Even a constructor would lack the capacity to assimilate all its stimuli, learning, and internal classifications; duplicating its structure and environmental history would effectively require another rat. The implication for understanding human beings is a limit on exhaustive explanation, not a denial of physiological organization. Hayek closes by welcoming cognitive psychology’s developing ability to give meaning a place within the physical world, while leaving intact the distinction between explaining an organizing principle and reproducing every operation it makes possible.