(FORTUNE Magazine) – In which Kindly Dr. Keeping Up escalates an argument that has thus far consisted of one published item (March 11) that groaned extensively about the / overpayment of unionized airline pilots, with special reference to the tactics used by the pilots at American Airlines to get raises, and a subsequent artillery barrage from the pilots. Dear Doc: You are hinting that the flypersons' letters do not endorse your idealistic vision of a world in which pilot pay is determined by market forces and not by monopoly power backed up by strike threats. Sad to say, the term ''market forces'' causes these guys to recoil like Dracula before the cross. Dear Kindly: Which implies they also failed to ratify your doctrine of the consumer-as-ultimate-employer and its corollary, which is that the flying public will ultimately decide if pilots making over $150,000 are overpaid. Oddly enough, a number of the missives, including the fax from Former Strike Preparedness Communications Spokesman Denny King, seemed rather fond of the aforesaid doctrine, or at least of a version of it in which pilots who subscribe to FORTUNEget to vote on our compensation. Dear Up: Were you surprised to find so many subscribers among union stalwarts? These stalwarts are not exactly proletarians. They come across as highly educated professionals; one identified himself as a Reaganite, a classmate and admirer of Ollie North, and a Keeping Up fan, which almost but not quite caused us to wonder if monopoly pay rates make sense after all. Dear Upkeep: How do these educated aces justify forcing kindly passengers to pay these monopoly rates? They say many things, none germane. They say the pilots bear awesome responsibilities. They ask whom we would prefer at the controls: a guy like Air Line Pilots Association member Al Haynes, the hero of the Sioux City, Iowa, crash landing that saved 186 lives, or some unmotivated character hired by a cost-obsessed airline management. We keep doggedly insisting, however, that Al would have been no less motivated without a union membership card in his wallet, and anyway, certain bibulous Northwest pilots possessed the selfsame cards. Dear Keeping: Do you find that such arguments win over your pen pals, and if not are you planning to don armor on future American Airlines flights? Negative to both questions. The aces also keep pointing out that pilots do not earn $150,000 a year when first hired, but only after about 15 years; also that they have previously undergone years of training. Dear Dr. Up: And they are unable to see why all such arguments are quite irrelevant? Yes, it seems hard for them to grasp the fact that the first effect of unionism is to shut out other pilots who are more than willing to tackle the same career while extracting lower charges from the paying passengers. Or to grasp the additional and larger fact that the imposition of these monopoly- driven costs works to reduce overall demand and output in the airline sector. Dear Doctor: Will the unions ever embrace these basic economic principles? In their own crafty way, the unions have already embraced them. A number of them -- most recently, the pilots' union at Northwest -- have accepted below- scale pay and benefit packages in an effort to preserve jobs and keep the airline flying. An implication you could extract from this behavior is that normal union pay and benefits work to destroy jobs, and airlines. Dear Kindly: You might reconsider about the armor.