We make irrational decisions and simple mistakes every day. What's more, knowing that we do doesn't stop us from making them again. Why? Because that's just how we are and we'd best get used to it, argues Dan Ariely in Predictably Irrational. In this exclusive extract, he explains the cost of free goods
Darwin was born 200 years ago, and 50 years later unveiled his theory of natural selection. To mark these anniversaries we bring you the definitive guide to the naturalist's great book, with extracts from key chapters and essays from leading scientists and thinkers including Richard Dawkins and former Bishop of Oxford Richard Harries
ID cards and detention without trial get plenty of coverage – but many other recent laws have ramifications for individual freedom. As the Convention on Modern Liberty approaches, Comment is free contributors look at how they could affect everyone – from infants to football fans, NHS patients and anti-Heathrow protesters
Two of the defendants in the Pirate Bay trial (#spectrial if you're following it on Twitter) gave evidence today in the case in a Swedish court. They said they don't read contracts they sign, don't check the speeches they write, and the law - well, what's the use of that?
Get real. Keep your head screwed on. What result do you want? I will assume, dear Guardian reader, that like me you have two prime purposes. One is to prevent Cameron walking into Downing Street on 7 May. Equal first is to secure electoral reform so that we are never again presented with such a disgraceful voting choice. If that's not your view, you can save time, stop reading here and push off to some Murdoch organ that will amply satisfy your needs.
NSA staff drew a smiley face to illustrate the point where the agency intercepted the transfer of user data between Google's international data centers. The diagram prompted an internet meme