But not everyone agrees. Dumbing down in the culture is like ME in the nation's health. Some deny it is there at all and we who complain about it should "pull ourselves together".
But I keep on coming across symptoms of our cultural stupefaction. For example, last spring I gave a semester of workshops at the University of North London. There were 23 students in the drama studies group. There were 10 all-day sessions, every Friday.
I did the workshops because I wanted to develop a new play. The idea was that I would get a new play drafted and they would learn something of how theatre is made.
I admired the students very much. Most of them were poor and struggling with money worries, exhausted by part-time jobs in pizza parlours, bars and clubs or cleaning offices in the dawn hours. I discovered that one was walking six miles a day to and from the campus to avoid paying for travel cards. Yet there was a toughness and independence about them. Also a degree in theatre studies is hardly an easy ladder to the conformist world of work to which undergraduates are meant to aspire in Blairistan. These were remarkable young people and this is not a 50-year-old's moan about their generation.
However ... oh dear God, what a bizarre experience the first session with them was! I would ask one student a question. But before he or she could open her mouth four other students in the room would answer and all at once.
Two students would be doing, say, an improvisational exercise. A bushfire of commentary would flare around the room as the exercise was in progress.
When one person was speaking, others would intervene, shooting off on tangents, often irrelevent. At other times, when something was really exciting us, the room was full of 23 students all talking to each other, to me and to themselves at once.
The group was large but this was not a discipline problem. They were keen and excited about the project. They were not unruly but impossibly chaotic: I seemed to be faced by a writhing snake-pit of intertwined monologues.
At lunchtime on my first day I was near panic. How could we have a calm discussion, let alone a productively heated argument? How could we build a story and scenes, developing one thing out of another?
Many of the students seemed to assume that there was no difference between thought and speech. Think it, speak it - at once. Simultaneous discourse a member of the UNL staff called it, with a weary laugh.
My first thought was: is this the fault of the schools? Have the rules of thinking been undermined by the box-ticking tests-as-lists teaching?
But a primary and a secondary teacher of long experience said that though they knew what I was talking about, "thinkspeak" behaviour is a new phenomenon. It has got worse in the past five years or so.
Their explanation was cultural. It's normal to talk in front of the television. You interrupt anyone because everything is interrupted. Chris Evans has a lot to answer for: he invented the studio full of voices saying anything, the gang behind him rabbiting on. Nineties children's programmes always have two or more presenters plus furry puppet, all talking or squeaking at once.
The dumbing down of the culture is corroding the rules of thinking. As in the hell of Beckett's late plays, to talk is to exist, to be silent is to be nothing.
I got good advice: set rules, use "trust" theatre exercises, tell them about the problem, emphasise form - in the play, in the plan for each day and the session. By the fourth session, things were much better and the course took off. I now have a new play, I hope the students have had some education in return.
I felt encouraged. You can reverse the effects of the dumbing down. But sometimes at night I dream that I enter in a room in which every mouth is open and thinkspeaking ...
Howard Brenton is a playwright