Part of the answer is the existence of shared norms, or professional doctrine. Experts often obtain professional qualifications from professional communities and receive training and supervision in their organizations. Doctors who complete their residency and young lawyers who learn from a senior partner do not just learn the technical tools of their trade; they are trained to use certain methods and follow certain norms. Shared norms give professionals a sense of which inputs should be taken into account and how to make and justify their final judgments.
