As a science fiction fan, I had always assumed that when computers supplemented our intelligence, it would be because we outsourced some of our memory to them. We would ask questions, and our machines would give oracular - or supremely practical - replies.

Though social eugenics was discredited long ago, we still often think of the genome in quasi-eugenic terms. When we read about the latest discovery of a link between a gene and a disease, we imagine that we've learned the cause of the disease, and we may even think we'll get a cure by fixing the gene.

The intersection of political analysis and Internet theory is a busy crossroad of cliche, where familiar rhetorical vehicles - decentralized authority, emergent leadership, empowered grass roots - create a ceaseless buzz.

The idea that our mental life is affected by hidden causes is a mainstay of psychology.