handwave

[possibly from gestures characteristic of stage magicians] To

gloss over a complex point; to distract a listener; to support

a (possibly actually valid) point with blatantly faulty logic.

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 wrong. 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.

[Jargon File]