Prevention of end stage renal failure.

mutual incomprehension is far from inevitable. Indeed, Popper demonstrates that in science competing paradigms may continue side by side for long periods of time, and that new paradigms do not obliterate old ones, but rather incorporate them into more successful models.7 Although the variously constructed models for the health service are political rather than scientific, the principle of adaptation and improvement rather than of conflict, victory and defeat, holds. Our papers were intended to offer the best available way out of what seemed to us to be the impasse of National Health Service general practice in the mid1980s.4Hart describes '...the old ramshackle independent professional paradigm', and chronicles the sad consequences of 30 years of professional burnout in the Upper Afan Valley since 1961.1 It may be timely to remember that prior to 1990 there were a number of perceived crises in the NHS. To suggest that those of us who sought to vary the arrangements for the NHS that were then extant, were in some way wilfully damaging a sound working model of public service on the basis of a speculative model of market economics, is to misremember history with a vengeance. The successful future of the NHS will demand not the collision of paradigms, but what Handy describes as the management of paradoxes.8 General practice has in the past been fairly successful in managing three quite different and mutually contradictory models of medical care the biotechnical, the biographical and the proactive. Now the challenge is to reconcile the new contractual accountabilities of a managed care model with the moral obligations of a professional public service. I realize that in prolonging this correspondence I risk the danger of this exchange of letters being seen as no more than a spat between grumpy old men. But I share with both Hart and Gray a sense of the importance of clarifying the history of events and ideas. One of the consequences of this correspondence has been to provoke me to re-read what I wrote and published a decade ago. Such reading is rarely an unmixed pleasure. However, I take courage from the writer Saul Bellow. In the preface to a recent collection of his own past essays he writes about the relative discomfort of re-reading ones own past pronouncements.9 He concludes drily that it gives great satisfaction '...to have rid oneself of tenacious old errors. To enter an era of improved errors.'9