Schumacher's principle that the size of an organization, technology, or institution should be matched to the scale at which human judgment can operate — and that scale exceeding this limit produces productive power at the cost of human control.
Appropriate scale is the organizing principle of Schumacher's economic philosophy and the structural counterpart to his other major concepts. Every institution, every technology, every organizational form has a scale at which it serves the people inside it and a scale beyond which it subordinates them. The ideal scale is the one at which the essential features of humane economic life can be maintained: mutual knowledge among participants, personal accountability for consequences, collective governance by the people engaged in the activity. Industrial economics had lost this principle because its logic rewarded scale — larger organizations produced more output at lower unit cost, so the market selected for size until the dominant institutions had grown beyond any human's capacity to comprehend or direct. Schumacher did not argue that small is always better; he argued that the question of scale should be asked deliberately rather than settled by default through the market's indifference to human comprehension.