Once in this capital, a while back, people got in a snit about unemployment and inflation and held hearings, which John Kenneth Galbraith, the combination economist-writer-professor-etc., duly attended.

"Everybody in turn said the cure was some course of action that benefited his institution. Thus, General Motors said the answer was to have more air pollution, the banks said the cure was something good for the banks and so on.

"Well, a reporter saw me and asked me to comment, so I said wait till that rubber corporation comes up with its solution. They are going to say the answer is more condoms. The reporter kept scribbling it all down. I had an awful time trying to persuade him it was a little joke."

And yet the little joke - which the reporter for some reason refused to relay though it was as interesting as anything else - contained a true jewel of truth:

People think that what is good for them is good for America. And government economists, Galbraith goes on, invariably predict that what an administration needs to have happen is what is going to happen. Thus all government economists, governed by the necessities of what ought to happen, should be taken with caution.

Galbraith is not quite sure, when he sits down for a chat, what to do with his feet. He is quite tall, and his legs have never yet met the cocktail table they could be happy with. Many men wonder vaguely what to do with their hands, but when people take a picture of Galbraith, he shuffles about until assured his feet will not be in the foreground.

He is a tolerant man, as all economists ought to be. He knows that not everybody understands his subject.

He knows many people suspect there is not evena subject there to understand. He is especially sure that some economists do not understand it. He alludes to Winston Churchill, who used to say that when military or labor or most other subjects came up in the House of Commons, he could understand them . But "I could never get my mind around economics," he used to say. "I do think that shooting Montague Norman would be a good thing," Churchill said.

Norman was the Bank of England. Galbraith cites the example of Churchill, either because he sympathizes with those who flub economics or because he thinks shooting bankers would be a good thing, in selected instances.

He is always appalled, he said on a recent visit, at the unhealthy look of Washington reporters. That was at a breakfast. True, of course, but then many things are true that you don't open conversations with.

He has conceived an awe of television. He has made a series of TV shows on economics that was a great success in England and is now showing in Canada, and which begins in America on Public Broadcasting tonight. (See review on Page C13).

"I write succinctly," he said, using the third-choice pronunciation of that word, "but the television people would say, 'fine - now could you get that down to 5,000 words?"' so I would work hard a few weeks and get it down to 5,000. Then they would say, 'fine - but a bit on the long side,' and get it down to 1,000. Every writer should undergo that experience," he said (he is a professor at Harvard and likes to teach as he goes along) "and see how few words are needed to express even a complicated idea."

As far as that goes, you could read the Bible and Shakespeare and forget the rest, if economy is the true aim of writing or of life, and Galbraith agrees that it's not how terse something is that counts, but what one is being terse about.

"For example, I was criticized for not treating Jeremy Bentham - there is some justice in the criticism. Bentham is the one who thought government should serve the greatest good of the greatest number. Imagine presenting that to the Senate. They are all Benthamites now - it is a common place now that government should do this.

"A Frenchman might say I pay too little attention to Say. Say is the author of Say's Law, that there can never be an absence of purchasing power. A beautiful and simple idea. Wrong, of course. Until 1940 you could not get a degree in econonics at Harvard unless you believed Say's Law. After 1940 you couldn't get a degree if you did believe it. Because Keynes proved the Depression resulted from saving. Anyhow, I think I should have had more on Say.

"I think more is probably lost in the selection (of what is to be written) than in abbreviation."

In his book, "The Age of Uncertainty," which discusses the ideas of economists from the 18th century on, and which all dutiful viewers of the TV series really ought to buy, Galbaith wanders a trifle from his usual succinctness and points out that the Goulds (a tycoon-type family of yesteryear) went second class and bought a count for Anna Gould to marry and never got any credit for it, while the Vanderbilts went first class and bought a genuine duke for their girl and therefore won a grand return on the investment. He also dips a bit into the Rockefellers and admits he hugely enjoyed relaying a notion of John D. Rockefeller's:

"The American Beauty rose can be produced in the splender and fragrance which brings cheer to its beholder only by sacrificing the early buds which grow up around it." That, Rockefeller said to his Baptist Sunday school, is a "law of God."

Galbraith accompanies this, in his book, with a page of Rockefeller portraits, called "The Natural Selection of the Rockefellers."

Young bud Nelson is at the bottom.

Galbraith's point, apart from taunting the Rockefellers, is that greed and rapine commonly find laws of God to support them. It was so in India, under England, or Vietnam, under America, or Constantinople under the Crusaders.

But if men act out of self-interest and summon God to endorse their avarice, then what good are high-minded economists or, for that matter, Harvard professors? Won't the world keep on the same, and won't circustances always rule, no matter how lofty people pretend to be?

One thing that happens, Galbraith says, is that those whose greed leads them to seize a colony (for example) soon weary of spending the necessary money and blood to keep it. The colonial power arouses hatred, but at the same time finds it harder and harder to maintain the myths that originally supported the system.

If such powers as the British had been willing to hold on, they could have kept India. It is one of his examples. But the British and all other colonail powers were unwilling to pay what it cost to keep the empire, and also they increasingly became unable to persuade themselves that the purpose of the empire was to bring God and law to the heathen.

It can be assumed from the start, Galbraith believes, that a colonial power will leave, since no people anywhere will accept a government (no matter how excellent) that is ethnically or geographically remote from them. Russia, he concludes, will run into enormous problems once it really involves itself in Africa. It will be like the English in India.

Is economics, then, an art like medicine, in which you take the illness and try to treat it?

"That's a bit unfair to medicine," he said.

"Economics is more like a priesthood or more like witchcraft."

People, in other words, who say they know what economics is about, and who can write books about it, become acknolwdged economists. Galbraith, at bottom, has a modest view of himself an his trade.

Someone once said that there is an undercurrent in him of deep compassion and ethical integrity, that keeps shining through his ironies.

Some of his best friends are enemies. He and Bill Buckley, the noted conservative (Galbraith is left of many middle-class liberals), have long been great friends. You would think there would be friction, but no.

"Buckley is a wonderful kindly man," Galbraith said in an improvised, ode to friendship, "and on all known questions he is quite wrong." This saves Galbraith a lot of time, in fields he has not explored himself.Buckley has looked into some matter, say, and Galbraith need not. He can safely take the opposite view and be right.

But as a writer, to get back to ethics, Galbraith says he tries hard not to protect his flanks. It is a major refinement, not to always be protecting yourself from criticism.

One reviewer said Galbraith is one of the great teachers of our time. Galbraith does not deny it - modesty is a severely overrated virtue, he believes.

"How can you say you are no good in economics?" he asked a fellow. "You have read my book. You know a lot. You are right up to date."

There was, unfortunately, one heroic taping of the TV series up in Vermont, a whopping 2 1/2-hour summation in which everybody like Kissinger and Heath and so on had come to take part. They shot 118 reels of film. It took forever to do, but all the great ideas were put in focus. Surely the exertion was worth it. But then, Galbraith said, it turned out none of the sound fitted the lips. How's that for being life you?