The cult of celebrity is not new, but it is increasing in its scope and effect. At one time, people wanted simply to gawp at the famous, and possibly dress like them. Now, many take their moral and political opinions from them.

For example, most young people's view of Africa, insofar as they have one at all, probably derives more from the pronouncements of Bono, U2's lead singer, than from any other source of knowledge about the Dark Continent.

As it happens, Bono has boned up on his subject, even if his conclusions about what should be done to help Africa are eminently disputable and deeply hypocritical. His authority arises from his celebrity, not from his knowledge. An equally knowledgeable but otherwise totally obscure person would not be able to hector the leaders of France, Germany and Italy for falling behind on their promises of aid, as Bono did last week. When Bono speaks, they have to listen — he is more famous than they are.

Fame confers authority, and the principal way of acquiring great fame is via the entertainment industry. Entertainers are the popes of our age, with de facto — though as yet not de jure — powers to call down anathemas on or beatify whomever they choose.

Entertainment is important because it is all-pervasive. Many people nowadays are growing up as if it were a gas in the atmosphere. They walk into the streets and vast plasma screens flash fast-moving images before them; their ears are stopped with iPods; at home, the television, or some other electronic entertainer, is on most of the time. People now grow uncomfortable, and even agitated, if they are left to their own thoughts for any length of time. When I was still in medical practice, more than a few patients used to ask me for pills to prevent them from thinking.

So it is hardly surprising that many young people, in particular, derive their political opinions as much from news presented as comedy as from more straightforward presentations. During the 2000 election campaign, the Pew Research Center found that 21 percent of 18- to 19-year-olds got their political news and views from "The Daily Show with Jon Stewart." His quick-witted and laugh-a-minute approach deftly avoids the greatest vice known to youth — squareness. Not to take anything too seriously is the highest form of sophistication, even if what is being presented is a partisan point of view. To say something and mean it is a sign that one is not of the exalted company of the hip.

Satire, of course, is one of the great resources of the human intellect — though it often seems to me (perhaps because of my advancing age) that satire nowadays often turns out quickly to be prophecy. But when satire becomes the dominant, or only, mode of communication, the result is a frivolous archness that in the end destroys the capacity or willingness for serious thought.

The cult of celebrity trivializes everything it touches. But then I ask myself: Was there ever a time in human history when people judged serious matters by serious criteria? If so, when was it, and when did it change?

Theodore Dalrymple is the author of "Our Culture, What's Left of It: The Mandarins and the Masses". He wrote this commentary for the Los Angeles Times.