"There is no sort of 'them and us', it is not that most people don't have paranoid thoughts and a few people have many, it seems that they are evenly distributed across the population, or many of us have them, much more than was previously thought. And actually there is also evidence that societies that are perhaps more unequal, have less social cohesion, are all societies where there is a bit more suspicion in the general population. So paranoia certainly can be a problem for the individual, and I work in hospitals and see people who have severe experiences, but also it's perhaps the mark of the health of a society, the levels of mistrust within it."