1) Privacy isn’t about hiding information; privacy is about protecting information, and surely you have information that you’d like to protect.
2) Privacy is a fundamental right and you don't need to prove the necessity of fundamental rights to anyone.
3) Lack of privacy creates significant harms that everyone wants to avoid.
Several small pieces of your personal data can be put together to reveal much more about you than you would think is possible. An analysis conducted by MIT researchers found that “just four fairly vague pieces of information — the dates and locations of four purchases — are enough to identify 90 percent of the people in a data set recording three months of credit-card transactions by 1.1 million users.” (Duck Duck Go, June 27, 2018)
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How would you feel if a government employee was keeping hidden files about you on a government computer network? You have nothing to hide... right?
Would it matter if the government agency involved had previously, in its own words, engaged in "a pattern of false arrests and detentions, attacks on homes and friendships, and attempted to impede [groups of citizens] from peacefully assembling... anywhere, at any time"?
Do you care if someone other than the intended recipient is reading your e-mail? What about having your e-mail scanned for key words like bomb, terror, drugs, assassination? They're just looking for terrorists, aren't they?
Should automatic license plate readers (ALPS) record every vehicle that passes some point on the highway, or enters the parking lot at some venue? You're on a public street... that's not private is it?
You don't have anything to hide, do you?
It doesn’t matter if you have nothing to hide. Privacy is an individual right that underpins the freedoms of expression, association and assembly; all of which are essential for a free, democratic society.
Arguing that you don’t care about the right to privacy because you have nothing to hide is no different than saying you don’t care about free speech because you have nothing to say.