Quick Definition: The over reliance on credentials
From Rational Wiki:
Credentialism is excessive reliance on credentials, especially academic degrees. The term originally was applied to over-reliance on credentials in hiring but its use has broadened.
Credentials (from the Latin credere, “to believe”) are third-party acknowledgments that the holder possesses the requisite knowledge and clearance relating to a specific field of knowledge. Most are educational in nature, usually a diploma indicating the completion of a specific course of study (high school, bachelor of science or arts, graduate degree, Minesweeper Consultant and Solitaire Engineer, etc.). Professional credentials such as press passes or convention badges indicate a right to a certain level of access, as do governmental/military credentials.
Ideally, credentials are an attempt to solve the problem of finding expertise: if someone has the appropriate credentials, we can assume they’re close enough to expert. Less ideally, they are a union card (it’s hard to get even a crappy academic job without a Ph.D.) though this can be an example of a well-intended system occasionally going wrong. Even less ideally, credentialism can be used to bully others or to dodge examination of one’s ideas: “I’m a Ph.D. and you’re not.”