We do nothing wrong when we make love or go to the bathroom. We are not deliberately hiding anything when we seek out private places for reflection or conversation. We keep private journals, sing in the privacy of the shower, and write letters to secret lovers and then burn them. Privacy is a basic human need.
The big problem with this argument is that the people who force privacy issues out into the open aren't people having affairs or weird hobbyists. They're criminals.
An example -- discussion recently about whether to put cameras on Austin streetcorners. In public places. Pointed at public intersections. Pros: Austin has a huge hit and run problem, especially against bikers -- this will end that and save lives. Cons: it infringes upon my privacy. What?!
How many of us have paused during conversation in the past four-and-a-half years, suddenly aware that we might be eavesdropped on? Probably it was a phone conversation, although maybe it was an e-mail or instant-message exchange or a conversation in a public place. Maybe the topic was terrorism, or politics, or Islam. We stop suddenly, momentarily afraid that our words might be taken out of context, then we laugh at our paranoia and go on. But our demeanor has changed, and our words are subtly altered.
This has never happened to me, and if it were to, the logical solution would be to move to a place where I could reasonably expect privacy. Not a park or the workplace.
The most common retort against privacy advocates -- by those in favor of ID checks, cameras, databases, data mining and other wholesale surveillance measures -- is this line: "If you aren't doing anything wrong, what do you have to hide?"
Well the most common answer is a logical fallacy: the slippery slope. "If we don't protect our privacy explicitly, we are going to wake up in Ukraine tomorrow."
EDIT: I have more. The pro-privacy argument basically hinges on this: we want to complain now, because it's better than waiting too long and not being allowed to complain at all. That makes some sense, in certain contexts. The issue is when it hinders rationality, when it allows assholes to kill cyclists because I don't want a camera on me when I'm stumbling home drunk from the bar.