The ubiquity of digital gadgets and sensors, the pervasiveness of networks and the benefits of sharing very personal information through social media have led some to argue that privacy as a social norm is changing and becoming an outmoded concept. In a seven-part series Don Tapscott questions this view arguing that we each need a personal privacy strategy. This post is Part Five of that series. For previous articles go here.

The most powerful forces making the case for sharing personal information are not philosophers or media pundits -- they are social media companies and other corporations who have a lot to gain from our social norms about privacy changing.

As the Net becomes the basis for commerce, work, entertainment, health care, learning, and much human discourse, each of us is leaving a trail of digital crumbs as we spend a growing portion of our day touching networks. The books, music, and stocks you buy online, your pharmacy purchases, groceries scanned at the supermarket or bought online, your child's research for a school project, the card reader at the parking lot, your car's conversations with a database via satellite, the online publications you read, the shirt you purchase in a department store with your store card, the prescription drugs you buy -- and the hundreds of other network transactions in a typical day -- point to the problem.

Computers can inexpensively link and cross-reference such databases to slice, dice, and recompile information about individuals in hundreds of different ways. That means companies want to know more and more about what makes each of us tick -- our motivations, behavior, attitudes, and buying habits. The good news is that companies can give us highly customized services based on this intimate knowledge -- and build trusting relationships. Sometimes it is great to have highly customized ads. I don't want to hear or see car ads except when I am interested in buying a new car. When I am, I would like to advise the car companies to bring it on!

But there is a dark side. Companies can use our personal information to our disadvantage. Some of these are rogue "bad actors." In the Rupert Murdoch tabloid scandal in the UK, cellular phone company technicians could sell the location of a specific phone. This way Murdoch's reporters could track down celebrities.

However, many companies have no problem trying to convince customers to do things that are not in their interests. Millions of homeowners got a taste of this in the sub-prime mortgage scandal. They were seduced into purchasing homes they couldn't afford.

Now, imaging a world where corporations have near perfect information about each of us. As the aphorism goes "Knowledge is Power." Could firms go beyond fairly influencing us, to being able to manipulate us? Could they abuse their detailed knowledge and cause us to purchase goods or services or take other actions that are not in our interests?

We already live in a consumer society where people go into debt to purchase things they really can't afford. If corporations had information about our every purchase, articles we read, movies we watch, things we say, places we go, food we eat, medications we take and "big data" from myriad other sources, how could they use that asymmetrical power to advance their interests against ours?

Sometimes the information is used in a very round-about way. Drug companies buy information from pharmacies about the drugs that doctors prescribe to their patients. That way they know which doctors to target for their advertising and promotional campaigns, with the intent that the doctor starts prescribing different drugs.

So given that there are few controls and even fewer companies that practice "privacy by design," it makes sense to be cautious about what information you provide. Don't fill out warranty cards. A warranty is valid whether or not you fill out a card. They simply provide information about you to companies. Refuse junkmail and take time tweaking your spam filter. Don't let a merchant copy your drivers license. Never give out your social insurance number unless it's legally required. Make sure that online forms are secure. Don't automatically consent to the collection, use or storage of your personal information. Question why people want your personal information. Make it clear that you do not wish your information to be disclosed to any third party. There are many things you can do, while we wait for companies to change how they treat our data.

Moreover, the information you provide has value -- to market researchers, advertising companies social networks and other online platforms. But most companies disagree that individuals own the rights to such information, since people provide the data for free or nearly free. The entire value of Facebook, estimated at $100 billion, for example, is the knowledge it has of its users: their likes and dislikes, what they say, what they do, where they shop, who are their friends and so on.

The degree of detail Facebook has is unprecedented. Facebook pays no users any money in exchange for this information. Facebook insists that it provides a superior service as a result, and that is sufficient payment. The same is true of Google. It prides itself on its accurately targeted advertising, for which its advertising clients pay top dollar. None of this money is shared with Google's users, however. If they are selling your information without your permission, they are depriving you of the opportunity to capture that income yourself.

The situation become more grim when companies exchange information with one another or with different arms of the same corporation, taking a series of seemingly simple isolated acts and compiling them into a detailed profile of an individual's behavior. Google recently announced it would share information across its search engine, YouTube downloads, Gmail use and more than 50 other separate services the company provides. Again, this is done so that Google has as detailed a profile of individuals' behavior as possible so that advertisers will pay more for the possibility of influencing your behavior.