JargonFile/entries/handwave.txt

handwave

/handwayv/ [poss. from gestures characteristic of stage magicians] 1. v. To
gloss over a complex point; to distract a listener; to support a (possibly
actually valid) point with blatantly faulty logic. 2. n. The act of
handwaving. Boy, what a handwave! If someone starts a sentence with
Clearly... or Obviously... or It is self-evident that... , it is a good bet
he is about to handwave (alternatively, use of these constructions in a
sarcastic tone before a paraphrase of someone else's argument suggests that
it is a handwave). The theory behind this term is that if you wave your
hands at the right moment, the listener may be sufficiently distracted to
not notice that what you have said is bogus. Failing that, if a listener
does object, you might try to dismiss the objection with a wave of your
hand. The use of this word is often accompanied by gestures: both hands up,
palms forward, swinging the hands in a vertical plane pivoting at the elbows
and/or shoulders (depending on the magnitude of the handwave);
alternatively, holding the forearms in one position while rotating the hands
at the wrist to make them flutter. In context, the gestures alone can
suffice as a remark; if a speaker makes an outrageously unsupported
assumption, you might simply wave your hands in this way, as an accusation,
far more eloquent than words could express, that his logic is faulty.