Why do competence theories use the idea of an ideal rational actor?

In the philosophy of social science, competence theories are designed to explain human behavior by identifying the underlying principles of rationality or systems of rules that govern specific activities.1

These theories utilize the concept of an ideal rational actor—an individual who has perfectly mastered the relevant norms or rules—as a methodological tool to define and describe those rules in detail. By modeling how such an idealized agent would behave in various situations, researchers can clearly articulate the standards of competence required for a given activity, such as linguistic communication or economic reasoning.1

Essentially, the ideal rational actor serves as a benchmark. Because meaningful actions often consist of following procedures (like the linguistic rules required to christen a ship or the economic principles used to maximize profit), social scientists must first establish what constitutes "correct" or "competent" performance. By discovering how a perfectly rational actor would navigate these rules, theorists can provide a precise, detailed account of the norms that shape actual human behavior.1