Because nobody, as far as I know, has brought together the issues of knowledge and control yet.

In short, my argument goes something like this:

1) It is possible to manipulate or influence people. This extends to their memories, perceptions, emotions, actions, even complex beliefs. And it can be more or less direct. Humans think of themselves as special snowflakes, but we are actually quite simple.

2) The degree to which one can manipulate or influence other people depends on

___a) the effort and intelligence one expends on it,

___b) the degree to which one has knowledge about the target, and on

___c) how close one is to the target (i.e. are you "under their skin", in their house, or 10 km away; what are your intervention options).

3) As social animals, we have always been subject to the influence of other people. Usually, this influence has been local, fuzzy, costly, relatively obvious to the target and "controllable" (in the sense that knowledge about target was strongly negatively correlated to (generalized) distance; if target became suspicious of you, target could simply cut you off or increase distance).

4) Technology and science currently change the rules of the game, and in profound, basic ways:

___a) We learn more and more about how to influence people, both by physical means (regulating temperature, lighting or noise conditions; psychotropic substances or, you know, food; changing the color of a button or playing with the timeline of events; etc.) and psychological means (e.g. using the right words or framing to elicit a certain response or evoke a certain emotion; exploiting properties of the social graph; etc.). This knowledge is, of course, still very imperfect but it is also cumulative.

___b) More and more of our interaction with the external or social world becomes mediated by technology ⇒ the options to intervene in the life of someone multiply as technology becomes a more integral part of life. As a result, it becomes very cheap to make targeted interventions in someone's life. Example: Today, ranking of search results or filtering of news; tomorrow, entire articles machine-written for you (personally). Automated homes. The mind boggles with the possibilities of augmented reality and/or immersive experiences. Farther out: Optogenetics.

___c) Deep and very detailed information about people can be collected in real-time and stored cheaply (no memory decay). The more ingrained the tech, the more detailed the data. For example, real-time monitoring of blood sugar and, in the future, perhaps even stress hormone levels.

___d) Physical distance becomes meaningless.

5) Due to the tendency towards natural monopolies in the sector, all this information and power accrues in very few hands ⇒ strong and unprecented centralization of both fine-grained knowledge about individuals as well as the means to intervene in their world without regard to distance or cost.

It is not hard to see that, to indulge in some hyperbole, "mind control" of a large population undermines traditional means of checking power. Who cares about elections if I can control whom people like? Why bother with competitive markets if I can make people want whatever I have to give (and make them pay reservation prices)? No more need for violent suppression of dissent because I can detect and change inconvenient ideas surgically.

To be clear, I am not saying we are already living in a mind-controlled society.

What I am saying is that collecting data (or rather letting someone collect data) about us is an integral part of this scenario. If data became more compartmentalized and limited, say, this whole thing wouldn't work (or be far less effective).

In fact, because technology and science progress anyway, how we handle our data may be the only way we can influence the course of events in this respect.

At least to my mind, this is the real issue of privacy. Alas, I seem to be alone so far. It's really hard to see for me why this is not totally obvious to everybody. I should finally write that essay that I've been meaning to for the longest time. Then someone can at least attack my argument. Sometimes, in your weaker moments, that nobody seems to see what you see can make you question your own sanity...

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PS: I am also not claiming that Larry Page or Mark Zuckerberg are rubbing their hands gleefully ("hihihi") at the prospect of world domination. I think concrete persons are incidental to this scenario. Heck, the one who ends up controlling, in this scenario, might not even be human. It just doesn't matter who. If it is technologically possible, it will be done. Loss or neglect of privacy makes it possible.