We all sort of know about brainwashing - it features in dystopic SF movies and is the sort of thing that dodgy religious cults get up to. It sits in the same box as 'gay cures' and the scarier end of drug-abuse therapy - something that's probably causing more mental health damage that any good (assuming there was good in the first place).
Watch out as the use of these techniques become medicalised - because 'extremism' and 'fundamentalism' are not matters of agency but involuntary consequences of socialisation or 'brainwashing':
Kathleen Taylor, a neurologist at Oxford University, said that recent developments suggest that we will soon be able to treat religious fundamentalism and other forms of ideological beliefs potentially harmful to society as a form of mental illness.
Read through what this researcher is saying. Read it carefully. It's not pretty is it? Dr Taylor goes on:
She said that radicalizing ideologies may soon be viewed not as being of personal choice or free will but as a category of mental disorder. She said new developments in neuroscience could make it possible to consider extremists as people with mental illness rather than criminals.
She told The Times of London: "One of the surprises may be to see people with certain beliefs as people who can be treated. Someone who has for example become radicalized to a cult ideology -- we might stop seeing that as a personal choice that they have chosen as a result of pure free will and may start treating it as some kind of mental disturbance."
OK you say - this is about saving people who have been brainwashed by the cult (perhaps up to and including paying £3 to join the Labour Party so as to vote for Jeremy Corbyn). But it's a good thing - we'll be treating the ill you see:
"I am not just talking about the obvious candidates like radical Islam or some of the more extreme cults. I am talking about things like the belief that it is OK to beat your children. These beliefs are very harmful but are not normally categorized as mental illness. In many ways that could be a very positive thing because there are no doubt beliefs in our society that do a heck of a lot of damage, that really do a lot of harm."
This is a recipe for a state-determined definition of 'normal' with anyone holding views that are outside the norm and defined as 'harmful' categorized as mentally ill. This is the medicalisation of brainwashing with the intention of treating the ill-effects of the wrong kind of ideology or belief.
On a much larger and potentially more fruitful scale is the recognition that the entire domain of religious beliefs, political convictions, patriotic nationalist fervor are in themselves powerful platforms for nurturing "Us vs Them" paranoid delusional fantasies which work out destructively in a 9/11 attack or a Hiroshima/Nagasaki orgy of mass destruction.