La Place de La Concorde Suisse, by John McPhee. New York: Farrar, Straus & Giroux. 150 pp. $12.95. JOHN McPhee can make anything interesting. In the years since 1965 - when he published his first book, a long profile of Princeton University basketball star Bill Bradley titled ''A Sense of Where You Are'' - he has written 16 books, each one masterfully crafted and each one inevitably making McPhee's latest fascination a part of his readers' lives.
McPhee, for example, illuminated the perplexing subject of plate tectonics with ''In Suspect Terrain'' and ''Basin and Range''; studied oranges in ''Oranges''; examined the life and work of an eccentric craftsman in ''The Survival of the Bark Canoe''; showed us the life of a prep school master in ''The Headmaster''; and, in his first best seller, ''Coming Into the Country,'' gave us an unusual look at Alaska.
In his latest book, ''La Place de la Concorde Suisse,'' we find the well-traveled New Yorker staff writer in Switzerland spending time with the Swiss Army. He begins: ''The Swiss have not fought a war for nearly five hundred years, and are determined to know how so as not to.''
As most of us know, Switzerland is the quintessential neutral country. It avoided conflict during World Wars I and II, defending itself, says McPhee, ''on what it calls the Porcupine Principle. You roll up in a ball and brandish your quills.''
To assume such a national posture, there must, of course, be an army to back up the implied threat. In Switzerland, 10 percent of the population is in the Army, yet professional soldiers account for less than one-half of 1 percent of that total. The rest are volunteers, and it is with them, on their summer training, that McPhee spends most of his time in his new book.
We learn, with McPhee as a nearly invisible interlocutor (so clean is his prose), that, although Switzerland is a place where everything is in precise order and the landscape is the stuff of post-card dreams, ''there is scarcely a scene . . . that is not ready to erupt in fire to repel an invasive war.''
''One does not have to be trained by the Central Intelligence Agency to see the airstrips like Band-Aids all over the Alps. . . . In forests are many clearings that seem to make no sense. . . . They are fields of fire. Hidden in the rocks behind them are extremely modern cannons trained on something . . . that might need the instant attention of prepared fire. All calculations are long since logged, and the shells are ready to fly.''
McPhee talks with soldiers from all ranks, from private to divisionnaire. He describes armaments and recounts Swiss military history. He tells of the Swiss' total preparedness, even for atomic war, and speaks of their '' 'aptitude for war.' It appears to be an appetite as well - sublimated and under close control.''
What sets McPhee apart from any number of other fine nonfiction writers is not simply his Swiss-like attention to detail, but a prose so precise as to allow the subject to shine through without obstruction. McPhee's writing is so good as to seem effortless, simple. But, of course, it isn't simple. It is, however, beautiful, and in ''La Place de la Concorde Suisse'' it is on exhibition.