Just as it is the doctor's job to heal, it is the scholar's job to know. Scholars don't have to know everything, of course, and every job involves some knowledge, but scholarship is oriented around knowledge in a special way. Where other people apply knowledge to the problems of living, scholars conserve knowledge and manage its development. They know enough about their area to recognize a novel idea, for example, and to evaluate it when it arises. They also know enough to be able to decide whether an event challenges our presently held beliefs. They carry out these functions in conversation with other scholars, and we call this discourse. They may contribute to "the growth of knowledge" either by validating a new idea in the discourse of their field or by invalidating and old one. But this is by no means a frictionless affair; scholars will often meet resistance from others who know as much as they do. In practical terms, then, their knowledge is just their ability to hold their own in conversation with their peers.
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This is the first in a series of one-paragraph posts. The goal is to write each of them in 30 minutes. They should be about six sentences long and under 200 words. This one is 178 words long and consists of 8 sentences. [Update at 11:39: I just removed a word and added a period.]