As an innovative psychiatrist, Dr. Karl Menninger, who died July 18 in his native Topeka, Kan., understood that the twin of mental illness was mental dullness. The second could afflict whole societies. Led by the dullish, they could become as out of touch with reality as the psychotic lost in catatonic torpor.

In seven decades of writing, teaching and lecturing, Menninger worked to inspire both his profession and country to move beyond the intellectual dullnesses that emphasize solving problems rather than preventing them. The question he asked of his colleagues -- ''Why is it that we psychiatrists don't take more interest in keeping people well and preventing them from getting sick?'' -- was thematic in the best-known of his books: ''The Human Mind,'' ''Love Against Hate,'' ''Sparks,'' ''Whatever Became of Sin?'' and ''The Crime of Punishment.''

At the 50th anniversary of the Topeka Menninger Clinic and Foundation, which he helped found and then nursed into worldwide leadership in the practice of progressive psychiatry, the physician and psychoanalyst reflected: ''Most of my life has been spent in treating persons one by one. But as I become increasingly aware of the extent of misery and hopelessness in our society, I think more of preventing unnecessary suffering at the source, before individuals take or are forced to take the wrong road.''

Among those wrong roads was the wide one leading to prison. ''The Crime of Punishment,'' published in 1966, reveals Menninger as the rare psychiatrist who saw as much sickness in society's treatment of criminals as in the offender's original crimes. Much like Rachel Carson's ''Silent Spring,'' which appeared four years earlier, Menninger's work retains the radical freshness that marked it a quarter-century ago.

''Perhaps our worst crime is our ignorance about crime,'' Menninger wrote. He detailed the failures of contemporary punishment, the uselessness of prisons and the immoral violence of executions. The ''crime'' in the title of his book, he wrote, is used ''in a somewhat poetic sense, inasmuch as there is no law against conscientiously making absurd decisions and going through ridiculous procedures.''

With a national surge in both prison construction and death-row executions, and with no related lowering of the crime rate, Menninger's progressiveness stands as a model of sanity. He cared as much for ex-prisoners as for the still-caged: ''Does anyone ask what useful things this man might do {on release}, what values he might render to society in exchange for the offenses he perpetrated upon it? Does anyone ask what might be done to redirect him? No, certainly not. ... Criminals are not to be 'helped.' Criminals are to be held, and hurt, threatened and warned, pushed and punished, released and paroled. But 'helped' -- for heaven's sake! Softheaded sentimentalism, liberalism, egghead stuff, practically communistic. These men are toughs. ... They should pay for their crimes. And keep paying.''

In 1981, Menninger, at age 87, received the Medal of Freedom, the nation's highest civilian honor. Intellectually, he was one of several 20th century socially involved physician/writers -- William Carlos Williams, Bruno Bettelheim, Benjamin Spock, Robert Coles -- who looked beyond their own disciplines for answers to what Menninger called ''The Great Riddle.''

''I am a doctor,'' he wrote, ''speaking the medical tongue with a psychiatric accent. For doctors, health is the ultimate good, the ideal state of being. And mental health -- some of us believe -- includes all the healths: physical, social, cultural and moral (spiritual). To live, to love, to care, to enjoy, to build on the foundations of our predecessors, to revere the constant miracles of creation and endurance, of 'the starry skies above and the moral law within' -- these are acts and attitudes which express our mental health. Yet how is it, as Socrates wondered, that 'men know what is good, but do what is bad'?''

Much of Menninger's writing was grounded in current events. In August 1972, when Sen. Thomas Eagleton withdrew as the Democratic vice-presidential nominee after disclosures that he had received electroshock treatments for depression, Menninger wrote that he would have voted for him: ''One can be even healthier than before after recovery from mental illness. But the public hasn't found this out yet.''

Of military ruthlessness, corporate crime, the assaults on animals and befouling of the environment, he asked in ''Whatever Became of Sin?'' -- ''All this, and nobody feels guilty? No one thinks any sin was involved?''

Menninger did. He had a type of secular holiness about him, befitting a psychiatrist to the ailing national soul.