As everyone knows, economists (and social scientists in general) can never agree on anything. They are for ever saying "on the one hand, on the other . . ." and "it all depends on . . ."

This, of course, has not discouraged them from making predictions with an aura of certainty traditionally associated with princes and eccentrics. But at heart many of us are humble (as the great Lord Keynes, himself among the most arrogant of men, decreed we should be). We are also envious of the true, bona fide scientist for his ability to be precise, to test hypotheses, to conduct laboratory experiments and to put forward provable propositions.

Alas! I had to find out the hard way that at least in that branch of science which most directly affects our daily lives--medical science--there is a degree of intra-discipline uncertainty, dissension and disagreement that would make any economist hold his head high in a gathering of professional men. This I had to learn the very hard way.

The story begins on the day of The Great Snow 1983 when I decided, involuntarily, to join the 7 million or so Americans who belong to that once exclusive but increasingly de'classe' group, the Back Pain Party (not to be confused with the Pain in the Back Party). Arriving at the office, and for no apparent reason, I experienced excruciating pains in the lower regions of the back. Retribution for past deeds? Revenge of vanity? Divine interference? These thoughts did pass through my mind, though they were overshadowed by a frantic search for The Healer.

The kind house doctor engaged to look after the health of the souls working for the organization to which I belong had, inexplicably, made it to work and, there being few potential patients on that morning, I had him to myself. Muscle strain, he pronounced after a certain amount of poking and bending. Rest. All will be fine.

Come Monday morning, and responding to that irrationality instilled in 20th-century man--that the expert always knows better than the generalist--I contacted a well-known orthopedist, the purveyor of medical comfort to one of the local sports teams (I forget which sport). Let's call him Dr. Aloysius Bonemender.

Altogether much more professional--he was a specialist wasn't he? Do this, bend that way, touch this part . . . and of course no examinaton by a medical specialist could be complete without a series of X-rays. Verdict: muscle strain, though he was careful to use the fancier term "lumbosacral strain."

That's what the house doctor said, for free, but I am sure it's worth paying $116 to hear it from the mouth of a specialist. Pills. Physiotherapy twice a week. See you in two.

The next phase was one of study and therapy, a total backward immersion, as it were. The physiotherapy consisted of lying down and being abused by a genus of expensive toy (it tickled, it pinched, it shook), which made you feel great for about 30 minutes. Not bad for $35 a go.

But I also made a big mistake, so far as the medical profession is concerned: I discussed my condition with friends, enemies and sympathizers, and I began to read about The Back. This latter practice is particularly frowned upon by many doctors who prefer illiterate, trusting souls for patients; I wonder whether passive "patience" has anything to do with the word "patient" . . .

Discussion brought a bumper harvest of suggestions: Go and see a neurologist, a chiropractor, an acupuncturist, a faith healer, an osteopath, a yoga teacher, a meditation instructor, a podiatrist (seriously), a psychologist, etc. Reading made matters worse, sowing increasing doubt and confusion as to my true condition. It also gave rise to great conflicts. The first was between the exercise regimen prescribed by the good Doctor Bonemender and a book on back problems written by several other Specialists of the Back.

What is good and what is bad for the back? Dr. Bonemender's specific instruction says: Lock your knees and touch your toes. The venerable tome says: Whatever you do, touching your toes is absolutely verboten! So much for that.

Matters did not improve. Dr. Bonemender, after many visits and several sessions of therapy, thought it might be something more serious than a simple muscle strain--er, lumbosacral strain. Go and see a neurologist, he ordered. He just happened to know of one housed conveniently in the same medical building. Have this, that and the other test done. We'll soon fix you. Thank you, that will be $44 (for 2 minutes flat).

The neurology center is as close as services can come to meeting Adam Smith's theories and Henry Ford's concept of the division of labor and mass production. In that sense, therefore, it may already be outmoded, in that they have not yet introduced robots, but I see no obstacles. The human body is passed along the production line and each operation administered without fuss or discussion. The three tests ordered were carried out: the first, electric shocks administered to the legs and feet, the second, deep sadistic insertions into nerves with long needles, rather like those of an acupuncturist gone mad, and the third a CAT scan.

Then see the neurologist in person. Let's call him Dr. Harry Plexus. Herniated disc, the verdict. Is that the same as a slipped disc? Yes. Fifty-fifty chance of cure. Surgery may be needed. (I'm sweating by now; blood pressure has gone through the ceiling.) Pills, four times a day. Come and see me soon. That will be $798 for the afternoon's troubles.

Dr. Plexus is positively jovial and chatty. I like him. He actually gives me 20 minutes of his time (Dr. Bonemender would have seen six patients in that time). He is also free with his opinions. I regale him in detail with the regimen of exercise I am putting myself through every morning.

But Dr. Plexus confuses me further by agreeing with some of the exercises recommended by his friend Dr. Bonemender, and disagreeing with others. He notices the book (remember, by the Specialists) I have brought for his assessment. After an instant analysis of the worth of the prescribed exercises, he asks whether he might make a photocopy of the entire book for "one of his friends." Hmmm. Hah. He proceeds to make the photocopy personally.

I make progress. Exercise. Care. Straight as a ramrod in everything I do. Shaving becomes a procedure with intriguing possibilities: How much soap will fall all around me before the operation is complete? Tying shoes--don't mention it, I have none with laces. Swim. Join club at exorbitant prices.

My troubles are not over: They are about to be compounded. Sometimes I can see the advantages of illiteracy. Out of the blue, there appears a major discourse by another Expert. Let's call him Dr. Debunk. He disagrees with everyone. There is nothing wrong with people's backs. It's all in the mind. That's the corpus vile. Good news for ulcers, who were beginning to feel lonely and frankly a little tired of being the much maligned refuge of the psychosomatic's Troubles. Misery-makers like company.

Dr. Debunk does not compromise. He characterizes as sheer bunk almost everything every other back expert has said. Want to lift weights? Go ahead. Sleep on a hard mattress. Not necessary. Man was not made to walk upright? Rubbish, he has been doing so for 5 million years. (Dr. Plexus, however, thinks 5 million years is but a short moment in evolution.)

Dr. Debunk does not explain how a psychosomatic ailment can occur suddenly. Perhaps the trouble was there all the time and the moment of agony (when you lift something and feel the back go) is only the point of cosmic transfer. If Dr. Debunk is correct, back problems definitely have a silver lining: you can exchange a back problem for an ulcer, or for endemic headaches, or for any other ailment that allegedly resides in the mind.

Dear sir, I am hopelessly confused, irretrievably confounded. Where does evil lie, down or up? Or is there a conspiracy between mind and behind? I beg to request enlightenment.