Compare and Contrast
Here's the clip of Gerald Ford's famous gaffe from the 1976 presidential debate, in which he denies that the Soviets "dominate" Eastern Europe.
It's pretty bad. But notice that Ford is struggling to make an intelligent and important point: what he wants to say is that the US does not concede the legitimacy of Soviet domination of Eastern Europe--and that the Helsinki treaty (which back then was attacked as a sell-out to the Soviets) does not contain such a concession.
The gaffe exposed President Ford's mental limits, which were real enough. But there's nothing here like the helplessness shown by Rick Perry--especially since (and unlike Ford's) the thought Rick Perry was struggling to express beneath his gaffe was itself dumb. Get rid of the Department of Energy? OK. But unless you simultaneously get rid of things like the Sandia National Laboratories, you're just engaged in tedious bureaucratic reshuffling.