What is explanation?

Explanation is the bread-and-butter activity of any technical communicator. We explain things for a living, but how well can any of us explain the nature of explanation itself? What makes technical explanation different from persuasion or narration? Web-based instructional systems have pushed us away from traditional kinds of paper-bound explanation. In these new realms, anything better than hit-and-miss success requires a clear sense of basic principles. With that in mind, I discuss the basic logic of explanation first proposed by the philosopher C.S. Peirce in the 1870s, and more recently extended by J. Hintikka (1998).