> maybe third party doctrine is obsolete in a world where people voluntarily give over to third parties every detail about their lives.

In these types of analyses, the doctrine of reasonable expectation of privacy is a good candidate to supersede the third party doctrine. The argument would be: I reasonably expect that the third parties whom I entrust with my private data and metadata will not disclose it except as required by the courts.

The question then is whether this expectation is reasonable. One theory holds that any time you give your information to anyone else, it's the same as giving it to everyone. You have no reasonable expectations that someone else will keep your data private.

But that theory seems outdated to me. Participation in modern society is preconditioned on trusting others with our private data. It's not optional. (The response that "you can always live in a cave instead" is neither realistic, humane, nor consistent with the values of a free society.)

Not only must you allow third parties access to your private data, you rarely have a meaningful choice about which third party, or the ability to negotiate the terms. Where I live, there is exactly one ISP. There are a number of cell phone providers, but to my knowledge, none offer a privacy guarantee, and I can't negotiate for one.

Because we have no choice but to trust third parties, it seems morally right that we should have a reasonable expectation of privacy when we do so. You can voluntarily surrender your privacy, and that's fine, but you shouldn't be forced to do so in everyday circumstances. This is a subjective judgment, but it's one I make based on what I consider widely held beliefs about the nature of a free society.

> In my opinion, privacy is obsolete in a world where people voluntarily give over to third parties every detail about their lives

The relevance or obsolescence of privacy is a spectrum, not a binary choice. Right now, we have less privacy than we used to, but we are far from the point of it being wholly obsolete. Have you really thought through what that world would be like? Are you OK with the idea that your every word and action is recorded forever and potentially subject to scrutiny by everyone who will ever live? (Extreme as that sounds, it's what we mean when we say privacy is truly and wholly obsolete. Anything less that that is just partway along the spectrum. So be careful when you say something like "privacy is obsolete" without any qualification.)

Consider the stress imposed by 24-hour surveillance. Every moment of your life, you would have to dedicate part of your consciousness to calculating how your actions may be interpreted by others, some of whom may be hostile to you.

When you search for something on Google, do you want your coworkers, bosses, friends, and enemies making inferences about your thoughts? Do you want to give potentially hostile parties the opportunity to build a damaging narrative around what are in truth innocuous searches?

When you begin typing a sentence, and then revise it because the first version didn't express what you wanted it to, do you want your critics to be able to read the first version and make claims about your "secret, true intentions?"

When you have a drink with your friends in the privacy of your own home, and you make an off-color remark, do you want to be the victim of an Internet witch hunt after it gets posted to YouTube?

When a gay middle schooler visits itgetsbetter.org, do you want the bullies at their school to know about it?

When you read a political blog, do you want your boss with diametrically opposed political views to find out about it and pass you over for promotion, never telling you why?

You may think these scenarios are far-fetched. But they are all logical implications of privacy's obsolescence. As I said before, anything less extreme would be an adjustment to our current notions of privacy, not the obliteration thereof.

Now, if you're arguing for the latter (adjustment not obsolescence), that's different. It's only realistic to believe that ideas of privacy change over time. And we must think carefully about how they're changing, and whether it's for the best. But that's far, far different from surrendering to the idea that privacy is obsolete altogether.