"The Reed-Kellogg diagram is a tool of the classroom and of the textbooks that codify the rules for its production. But grammar textbooks share a problem similar to the one Thomas Kuhn noted for science textbooks: they tend to efface the history of their subject. Indeed, grammar textbooks are far more ahistorical that science textbooks. The average science textbook will contain some history, however Whiggish. There will be at least a cursory mention of the scientists who formulated the theories under discussion, some suggestion that scientific knowledge is subject to change and accretion. Grammar, however, comes to students as an abstract whole. The sources from which the textbook authors derived their accounts normally go unacknowledged. There is no sense of grammar as a theory—or, more precisely, a constellation of competing theories—with its own intellectual history."
(Karl Hagen, 17 October 2015)