AMERICAN political life must be the only social and professional environment in the world in which, typically, you spend the first 40 years fighting your way out of borderline poverty and hardship and into country club posh--and the second 40 years bragging about how poor you used to be. Those were the days, all right--eh?

Sometimes the thing becomes competitive. You will have noticed that Speaker O'Neill and the President, for example, are at it again. It seems only yesterday, whereas in fact it was last June--one budget cycle ago--that Mr. O'Neill zinged Ronald Reagan about not understanding working people and Mr. Reagan zang back that he was "trying to find out something about his (the Speaker's) boyhood, because we didn't live on the wrong side of the tracks, but we lived so close to them that we could hear the whistle real loud." He knew the working class well, the President insisted.

Well, that one dissolved, as these nasty exchanges between the President and the Speaker tend to, in a shower of aw-shuckses and endearments. But another budget has produced another round. This time we have what Mr. O'Neill calls a "Beverly Hills budget." The Speaker also said that Mr. Reagan had "forgotten his roots" and had "associated with the country club style." To which the President replied with speculation about where Mr. O'Neill plays his golf, if not at a country club. And so forth.

Humble-origins chic, of course, has been the political fashion since long before these two contenders were on the scene. The purpose, which we have always thought a vain one, was to persuade voters that their leaders, even though currently being carted around in mile-long limousines, were deep-down merely sympathetic regular guys attuned to the fears and strivings of the working class. As we say, we have never thought the voters bought this pretension. On the contrary, it has probably only fed the impression of hypocrisy that well-off politicians, journalists, foundation-niks and others in the Washington political world exude when they presume to lecture on the subject of the workingman's ordeal.

The value, and voters know it, of that drafty old log cabin and the hand-me-down overalls is this: some politicians (Hubert Humphrey to take a case) transform their own recollection of poverty into an abiding concern to spare others its anxieties and deprivations. Others incorporate the experience into their political outlook mainly for its value as evidence that a determined would-be escapee can make it over the fence in this great land of ours. Still others may have other ways of relating their personal past to the present circumstances of working people. It is the resulting public philosophies and programs, not a contest as to who is or was more of a workingman's workingman, that matters. The White House is not a working class place, and that tax break that Speaker O'Neill just helped to give himself and his congressional colleagues is not something that your average hard hat either gets or gets to vote into law for himself. We think someone should change the subject.