Do megabuck sales actually cheapen art?

I wish Cezanne, Monet, Van Gogh, and Degas could have been there. Had they been, I doubt any of them would have believed it. Certainly not Cezanne and Van Gogh, and most assuredly not Degas. He would have been most surprised of all.

He would have had good reason. No pastel has ever sold for such a sum as $3. 74 million - or even come close to it. And it was one of his.

The fact that the sale was the highlight of an end-of-season series of major art auctions at Sotheby's (one of the world's two great auction houses) would have meant little to him - nor would the fact that the sale had attracted many of the world's major collectors, dealers, and museum curators.

What would, however, have stunned him, was the unbelievable price his pastel sold for. The $3.74 million figure certainly surprised me. I had expected it to go for $2 million at most, and I wouldn't have been surprised if it had gone for several hundred thousand dollars less. It was, of course, a great picture, but it was a pastel, and as such, technically ''only'' a drawing.

But ''Waiting,'' a medium-size study of a young ballet dancer and an older woman seated on a bench, triumphed over the usual prejudice against works on paper, and scored entirely on merit. I was pleased, as I also was by the response to other works by Degas and his great Impressionist and Post-Impressionist colleagues. And by the interest shown in the other auctions at Sotheby's (and at Christie's, the other major auction house) devoted to 20 th-century art.

I wasn't pleased, however, by the circus atmosphere that pervaded these sales , nor by the social and commercial attitudes that dominated them. The values of art were shoved aside by the concerns of wealth, power, and position to the point where the purchase and possession of art often became more a matter of prestige than of aesthetic pleasure.

All this shouldn't have bothered me, considering how long I've been a part of the art world and the number of years I've acted as an art appraiser. But it did , and I suspect it always will. I simply will never get over seeing art, the product of great passion, delight, love, and caring, treated as though it were nothing but a valuable piece of property, or something to hang on one's wall, at times just to impress the neighbors.

I realize there were genuine art lovers at these viewings, but I doubt they were among those individuals I overheard saying they needed a Klee to go with their tiny Dubuffet, or wanted a particular Picasso pencil portrait because it would look so impressive in their hallway. And I'm positive two young men deep in discussion about the advisability of bidding for the Schnabel were thinking almost entirely of their margin of profit, should they sell it in two or three years. If they weren't, why were they so concerned about the stability of Schnabel's reputation?

It's a pity art has become such a high-powered commercial enterprise. And yet there are compensations. These two series of auctions at Sotheby's and Christie's added up to some of the best art viewing of the season. Anyone interested in art could have seen hundreds of outstanding paintings, sculptures, constructions, drawings, etc., - as well as a handful of masterpieces - totally free of charge.

Of particular importance is the fact that such viewings are often the only time certain works will ever be seen by the public. Many of them come from private collections, and disappear into other private collections once the auctions are over. South America's Botero

Fernando Botero is that rare phenomenon in today's art world, an artist of international reputation who scaled the heights without affiliating himself with any of modernism's post-World War II movements. Even more unusual, he did it as a South American, an extraordinary feat in itself, since very few artists from there have yet achieved more than local or regional fame.

Botero was born in 1932, high in the Colombian Andes. He started to draw seriously while still a child and by the time he was 16 had established something of a reputation as an illustrator for the local literary magazine. In 1952, after two successful exhibitions in Bogota, he left for Europe.

While studying painting in Madrid and Florence, he fell in love with the works of Velazquez, Goya, and Giotto, an event which had a profound effect on the future course of his own art. By 1955 he was back in Bogota as a professor, and by the end of the decade he had evolved the basic elements of the style that would serve him well from then on.

This style was representational in approach, witty and ironic in attitude, and opulent in form. Everything he painted - but most especially children, vegetables, nudes, furniture, and cats - turned out plump and bigger than life. Fame came quickly - almost, it seemed, in direct ratio to the degree of rotundity his subjects reached.

An excellent miniretrospective of Botero's paintings is on view at Aberbach Fine Art here. Its nine very large canvases trace his career from 1962 to 1980 and include some of his better works.

It's a pleasure to see Botero at full strength - and without any of the superficially cute paintings that have overwhelmed so many recent shows of his current work. Those on view in this show are outstanding examples of each of his major periods, and they point up what a delightfully imaginative painter he really is. Of particular interest are two early single-figure canvases that would hold up beautifully in any exhibition of 20th-century art.

At Aberbach Fine Art, 988 Madison Avenue, through June 30.

Minimalism to Expressionism

Dramatic changes took place in American art between 1965 and 1980. Some were so startling, in fact, that some art lovers still refuse to believe they actually happened. The shock was too great.

For years they had been told that art was a matter of formal purity, simplicity, and sensibility. Then, within a year or two, the exact opposite stormed center-stage. Art became loudly expressive, brash, exuberant, and often ''tasteless.'' It was like being told that the statue of the nude mermaid with the clock in her belly that had always been held up as the ultimate in kitsch was now to be considered art.

''Minimalism to Expressionism: Painting and Sculpture Since 1965,'' at the Whitney Museum here surveys this significant shift in an exhibition of 57 works from the museum's permanent collection. Works by such artists as Andre, Stella, Judd, Hesse, Shapiro, Rothenberg, LeWitt, Salle, and Schnabel trace this period's shift from Minimalism to Post-Minimalism and then to today's Expressionism.

It's an excellent show. Patterson Sims, who organized it, is fast becoming one of our best and most influential curators. He has a good eye, boundless energy, and an enthusiasm for art that translates into some remarkable shows. Even when I disagree with him, I'm glad he's around.

At the Whitney Museum through Sept. 18.