Michael Fumento, an occasional Reason contributor, has just published an article in The New Republic; it's not simply a defense of the Attention Deficit Hyperactivity Disorder diagnosis, but an effort to persuade conservative critics of that diagnosis that it doesn't deserve their scorn. That goes a long way towards explaining why Fumento spends so little time actually engaging their arguments—his reply to the "myth [that] ADHD isn't a real disorder" basically assumes its conclusion—and so much time quoting famous conservatives who already agree with him. It may also explain why he doesn't acknowledge the large number of liberals and libertarians who share many of the positions he's criticizing.
In short, the piece left a lot of room for debate. Colby Cosh's reply to it is a good start.