Facebook have announced their first share offer. There was a fairly nuanced discussion on the BBC’s Today programme, which contained the useful maxim: if the service is free then you are the product. We pour personal information about ourselves – our locations, likes, friends and activities – into Facebook and Facebook sells that bit of us to advertisers. John Humphrys managed a grumble about whether we could trust a corporation with all that personal information, but nobody in the discussion seems to be able to raise much by way of concrete reasons not to give Facebook that information about yourself, they just had vague worries. Elsewhere, Cory has talked about the privacy bargain we make with corporations, and the dangers of making that bargain unknowingly or carelessly, but I want to leave that aside for a moment. Imagine a world where everyone was aware of exactly what Facebook were doing – ie selling information about our desires to advertiser. In this case, the vague worry about Facebook crystalises around a psychological question – can we be manipulated by corporations that know our desires? Imagine, if you will, that Facebook is the equivalent of the malevolent demon of Cartesian philosophy, still absolutely evil in intent, but different in that it can only control you through precisely targeted marketing messages, not through direct control of yours senses. Would you still sign up for a Facebook account? Say the Facebook Demon finds out you like lemons. Lemon Products Inc advertise you Lemon Perfume, LemonTech advertise you a lemon squeezer and Just Lemons Inc. offer you 10% off the price of lemons in their stores. Is this a bad world? The answer is only yes if you believe in the power of advertisers to make us do things we don’t want.