“many human skills are tacit because “the aim of a skilful performance is achieved by the observance of a set of rules which are not known as such to the person following them.” For example, swimmers are probably not aware of the rules they employ to keep afloat (e.g., in exhaling, they do not completely empty their lungs), nor are medical experts generally aware of the rules they follow in order to reach a diagnosis of a disease. “Indeed,” Polanyi says, “even in modern industries the indefinable knowledge is still an essential part of technology.”
―
Eric von Hippel,
Democratizing Innovation