This concept taken from a speech I recently saw on CSpan, given by Ed Brayton:
"In my speech at YearlyKos I'm going to address the problem of virulent ignorance, which is distinguishable from the sort of mundane ignorance that we all have about a great many subjects. Mundane ignorance is a mere lack of knowledge; we are all ignorant of far more subjects than we are knowledgeable of. Ask me about how to fix a car or about the history of choral music in Eastern Europe and I'm as clueless as can be.
"But because I know that I'm ignorant about those subjects, if someone were to ask my opinions about them I would say, "I'm the wrong person to ask, I don't know anything about it." Ask me whether one European soccer team plays better defense than another and I'm not even going to attempt an answer; I simply don't know anything about it and wouldn't be able to distinguish good defense from bad defense even if I spent the next 72 hours watching soccer games. That's mundane ignorance.
"Virulent ignorance, on the other hand, is when someone thinks they know something about a subject when they don't. Virulent ignorance is when someone has absorbed a set of platitudes or claims that they presume to be true without any real ability to evaluate whether they are or not. This type of ignorance is the brass ring of politics, the thing that all political movements strive to inculcate in as many people as possible.
"A politician or a political movement is most successful when they are able to replace the mundane ignorance of a large group of people with a set of pre-formed conclusions that they can offer as opinions without bothering to go through any rational process to reach those conclusions. This gives their followers a set of responses that they presume to be true and gives them the illusion of knowledge. It's what makes people offer opinions to poll takers on subjects that they know virtually nothing about.
