In Canada, the usual equivalent of 'not voting' is just deliberately spoiling your ballot. The argument being made is much the same as Elldallan's: If we just don't show up, politicians will think we don't care, that we're disengaged. The counter-argument, at least for spoiled ballots, is, "Great, instead you'll be lumped in with the demographic too stupid to properly mark an X in a box."

But even where there is a mechanism for deliberately voting 'none of the above' (and in fact, Canada has such a thing, though it's little known), ultimately it's pointless.

Politicians bank on low turnout figures. It's easier to manipulate the final tally by targeting specific demographics and running a good ground game, when the overall turnout numbers are likely to be low anyways. By *not voting*, whether deliberately or not, what you are actually *doing* is relegating your voice to those who do - and, specifically, the largest group who do. And the message you send to the politicians - the one they will take home, every time - is "Work harder to make the people who *actually* vote happier."