It looks like Gargoyle's site simply lists the Classical names of various figures of speech. DMcG's example, however, is not a figure of speech, it's a debating or propaganda technique of the sort beloved by all politicians, publicists, lawyers, and commercial advertisers.

If I understand McG's point correctly, one may describe the technique also as deliberate slanting, or the willful suppression of significant facts.   

My favorite example: Back in the '60s, Shell ran commercials that showed a half dozen identical late model cars lined up in the desert. Only one was fueled with "Shell with Platformate," a proprietary mileage additive. The rest ran on "ordinary gasoline."

At the signal, all the cars sped across the desert. But the car powered by Shell with Platformate kept on going after the others had run out of gas. So only a rich fool wouldn't fill up with Shell with Platformate every time, right?

Wrong. What the ad didn't say (besides just *how much* farther the Shell car traveled: maybe it was only a hundred yards) was that virtually every retail brand of gas was formulated with a mileage ingredient more or less equivalent to Platformate. Shell expected you to assume that "ordinary gasoline" meant the non-Shell kind. But it didn't. It meant gasoline with no mileage booster, and you'd probably have to drive to the backwoods of Transylvania to get it. (Not to mention that gas prices in any locality vary somewhat anyway, and speeding across the desert isn't quite the same as stop-and-start city driving.)

Thus the ad also dealt in "equivocation," which is the use of unclear or ambiguous language ("ordinary gasoline") in order to mislead.