The correspondence of expectations ... is brought about by a process of trial and error which must involve constant disappointment. The process of adaption operates, as do the adjustments of any self organising system, by what cybernetics has taught us to call negative feedback: responses to the differences between the expected and the actual results of actions so that these differences will be reduced. This will produce an increased correspondence of expectations ... (F.A. Hayek, Law, Legislation and Liberty)実際、負のフィードバックによって秩序が達成されるという洞察は、サイバネティクスが初めて体系的に理論化したといえ、何もサイバネティクスが創始した考えではなく、もともとは市場についての理解にこそその起源を持つ。
long before Claude Bernard, Clerk Maxwell, Walter B. Cannon, or Norbert Wiener developed cybernetics, Adam Smith has just as clearly used the idea in The Wealth of Nations. The "invisible hand" that regulated prices to a nicety is clearly this idea. In a free market, says Adam Smith in effect, prices are regulated by negative feedback. (G. Hardin, Nature and Man's Fate)ただし、これは時間と努力さえかければ学習過程が何らかの最終状態――主流派の「均衡」概念のような――に達しうるというわけでは決してない。オドリスコルとリッツォの次の意見に、おそらくハイエクも賛同するだろう。
A theory of evolved orders is not a theory of optimality or efficiency, precisely because it is a process not an end state theory ... It is not what competition does to fulfill our expectations that commends it; it is what we would not have expected it to do that commends it. (O' Driscoll, G. and Rizzo, M., The Economics of Time and Ignorance)抽象的・一般的ルールを遵守しながら、行為主体は試行錯誤のプロセスを通じて進まなければならないが、このプロセスは不可避的に、常に一定数の主体の期待が 裏切られることを意味するだろう。特定の不確実性の存在によってのみ、より一般的な不確実性を最小化することができるのである。
[Market-determined rewards are] incentives which as a rule guide people to success, but will produce a viable order only because they often disappoint the expectations they have caused when relevant circumstances have unexpectedly changed. It is one of the chief tasks of competition to show which plans are false. (F.A. Hayek, Law, Legislation and Liberty)期待が裏切られる過程で深刻な損害を受ける主体がいるということは不幸な副作用であるが、それを避けることはできない。というのも、介入は知識の発見・伝達・貯蔵を妨げ、それによって富の創造過程を妨げ、すべての人の好機を害するからである。
最後に、知識の発見手続きという意味における、市場競争と科学の方法との同型性について。
If we do not know the facts that we hope to discover by means of competition, we can never ascertain how effective it has been in discovering those facts that might be discovered. ... The peculiarity of competition - which it has in common with scientific method - is that its significance cannot be tested in particular instances where it is significant, but is shown only by the fact that the market will prevail in comparison with any alternative arrangements. The advantages of accepted scientific procedures can never be proved scientifically, but only demonstrated by the common experience that, on the whole, they are better adapted to delivering the goods than alternative approaches. (F.A. Hayek, "Competition as a Discovery Procedure")科学の方法は自然界の普遍的な事実、つまり法則を発見するのに対して、市場競争はあくまでその特定の状況でのみ有効な暫定的な事実を発見するがゆえ、後者の有用性は前者に比べて理解されにくいと言える。
