Recently there have been reports that terrorists [ or suspected terrorists ] were " extremely intelligent ", " a genius ", " a quiet loner ".......etc...The implication is how intelligent people can act [ in the questioners view ] so stupidly or irrationally.

I think this invites the argument about growing up or maturity in general. As I see it, people mature in three main ways-----physically, emotionally and mentally [ or intellectually ]. I think it's perfectly possible for a person to mature intellectually and physically and yet to remain a child emotionally.

This would account for the thousands [ maybe millions ? ] of cases where mentally capable people have managed to follow weird philosophies or act in bizarre ways.

I guess a classic example would be Nazi doctors who were obviously mentally able to some degree but who swallowed absolute piffle without the slightest objective evidence. They simply had a childish desire to fall in with the Nazis for one reason or another.

Is this true do you think ? And if so, there must be lots of other examples.

I don't think you even have to go to such extremes.

I've frequently argued that we've become an increasingly infantilised society - partially, I think, due to teh fact that housing pressures make it more difficult for people to establish their own homes.

I left home at 18, and it was made clear (in the nicest possible way) that whilst I would be welcome for visits and stays if absolutely necessary, I had 'left home'.

I shared a house at University, then rented with my wife until we could afford to buy after leaving Uni. By the age of 22 we were renting a house away from our birth places AND our University city.

Today many people seem to stay at home until their mid 20s or later, or end up carrying on with the 'house share' mentality that they had in college. Even when they buy, they frequently have to be massively supported by their parents. It's not surprising that people fail to grow up in these circumstances.

Added on to that the lack of consequences that most behaviousr have, and an increasingly narcisistic and hedonistic culture, failure to grow up is probably the best way to be in an increasingly play oriented and nannyish state.

Recently there have been reports that terrorists [ or suspected terrorists ] were " extremely intelligent ", " a genius ", " a quiet loner ".......etc...The implication is how intelligent people can act [ in the questioners view ] so stupidly or irrationally.

I think this invites the argument about growing up or maturity in general. As I see it, people mature in three main ways-----physically, emotionally and mentally [ or intellectually ]. I think it's perfectly possible for a person to mature intellectually and physically and yet to remain a child emotionally.

This would account for the thousands [ maybe millions ? ] of cases where mentally capable people have managed to follow weird philosophies or act in bizarre ways.

I guess a classic example would be Nazi doctors who were obviously mentally able to some degree but who swallowed absolute piffle without the slightest objective evidence. They simply had a childish desire to fall in with the Nazis for one reason or another.

Is this true do you think ? And if so, there must be lots of other examples.

some people never grow up, and may "stick" at a certain mental age - this could be for many reasons, brain damage etc.
i dont think you could say the nazi doctors had a childish desire to fall in with the nazis, they were doing a job, that they were ordered to do.