… is from page 305 of Vol. 19 (Ideas, Persons, and Events  ) of The Collected Works of James M. Buchanan ; specifically, it’s from Jim’s 1990 paper “The Potential for Politics after Socialism”:
Many modern scientists, secure in their own achievement of genuine discovery of new laws of the workings of the physical universe, and observing first hand the extension of humankind’s mastery as these laws are applied, exhibit a natural proclivity to attribute what seem to be flaws in the structure of social interaction to “scientific” backwardness, and to expect improvement from inappropriate extensions of science’s domain into the realm of social control.
DBx: Neither society generally, nor the economy specifically, is a machine. It is not the result of human design. It could not possibly have been the result of human design. It cannot be improved by design (despite the human mind’s ability to imagine social arrangements more “ideal” – according to each imaginer’s own preferences – than are those observed reality), although it can be allowed to improve itself if attempts to engineer it are avoided. It is not operated by anyone, by any council, by any cabal. Although it can be said to serve a function or several functions, it has no purpose in the sense of having a well-ordered set of preferences that it pursues.
Therefore, neither society generally, nor the economy specifically, is an engineering project. There is no scientifically correct – and, hence, no scientifically discoverable – optimal distribution of income, efficient portion of the economy devoted to producing services, or correct way of dealing with a pandemic. The sciences – natural and social – have much to contribute to informing individuals, including government officials, about the trade-offs involved in different courses of action. But science cannot tell us what to do; it has no power to reveal to government officials or to the general public any “optimal solution” that government should impose.
That this reality might be judged by many well-meaning people to be unfortunate, I concede. But this reality, like all reality, isn’t optional.