… is from pages 257-258 of Hayek’s 1992 collection, The Fortunes of Liberalism (Peter G. Klein, ed.), which is volume 4 of The Collected Works of F.A. Hayek; specifically, it’s from Hayek’s 1968 Il Politico essay “Bruno Leoni, the Scholar” (link added):
He [Bruno Leoni] argues persuasively, and has convinced me, that although the codification of the law was intended to increase the certainty of the law, it did at most enhance the short-run certainty of the law, and I am no longer sure that even this is strictly true, while the habit of altering the law by legislation certainly decreases its long-run certainty. He did show further that one characteristic of the rules of just conduct which emerge from the spontaneous process of law was that these rules were essentially negative, rules aiming at the determination of a protected domain for each individual and as such an effective guarantee of individual liberty. As to many other profound thinkers the task of the law was to him not so much to create justice as to prevent injustice.
At its best the use of force can prevent injustice. For example, I will point a loaded gun at you if you break into my home, and I will shoot you with that gun if you refuse to do exactly as I say as I summon the police so that they – also using physical force – can jail you. In contrast, physical force cannot be used to create justice. No human beings are sufficiently good, informed, and wise to be trusted with the dangerous power of using force to engineer from the top social outcomes that are better or more just (By whose criteria?) than are those outcomes that emerge spontaneously when each individual acts according to his or her own designs within a broad framework of ‘negative’ rules (“thou shalt not ….”).
Indeed, as Hayek argued elsewhere, the term “justice” cannot be meaningfully applied to undesigned and unintended spontaneous outcomes. For example, the distribution of income in a market economy can no more be “just” or “unjust” than can the pattern of migrating swallows or a tornado. Each of the individual choices and actions that give rise to that income distribution (or to any other observed spontaneous social order) can be assessed as being either “just” or “unjust,” but the overall pattern itself – being neither designed nor intended by anyone – is neither just nor unjust.
If the prevailing set of negative rules (law) is good, society will be largely prosperous and peaceful. If the prevailing set of negative rules (law) is bad, society will be filled with poverty and belligerence. And the reality is that in the latter case there’s very little that anyone can do – not the police, not a powerful legislature, not a strong-arming autocrat, not the U.S. military – to improve that society. While such force-deployers might succeed at preventing some of the worst injustices in that bad-law-ridden society, either the negative rules there will improve on their own over time through the changing ideas, norms, and expectations of the people, or they will not improve. Designing and imposing law is oxymoronic.
The common belief that law is synonymous with legislation is false, as is the equally common belief that law is improved and becomes more certain if it is written down in detail in words. Society is not a toy or a piece of furniture to be assembled; if it were, then its successful creation and maintenance would require (or be more likely to be achieved with) detailed written instructions – and each person would have a precise role to play. Instead, society is a stupendously complex web of human relationships formed spontaneously. Such spontaneous formation can happen only if and insofar as each person is free to choose within boundaries that are themselves determined spontaneously.
The human mind rebels against this realization that all genuine law is spontaneously generated and can only be spontaneously generated. We human beings seem naturally to suppose that some creator must exist at some level or stage in the process. But just as the order of the cosmos and of the natural world emerged spontaneously from its own forces – the forces of nature – the order of the social world emerges spontaneously. Governments are very good at playing at being a designing or an improving god – or at convincing the populace that such a secular god is necessary. But whenever (which is almost always) government does anything more than enforce negative rules of just conduct (such as preventing Jones from robbing Smith), it perverts the development of the spontaneous order. It injects disorder into the spontaneous order.