The impact of legal modes of thought upon the practice of psychiatry. The fifty-fifth Maudsley Lecture, delivered before the Royal College of Psychiatrists, 20 November 1981.

Almost invariably, a professional man becomes the captive of his chosen profession. His training and his subsequent experience in practice leave an indelible mark. It is often said that married couples grow to look like each other, and in extreme cases like their dogs. So lawyers, accountants, bank managers, doctors and perhaps even psychiatrists appear to take on a stereotyped form. The cartoonist spots the uni form clothes, the rimless glasses or the mid-European accent, as the trade mark of the particular profession. But more crucially there is also the growth of stereo typed modes of thought, of common assumptions and traditional patterns of argument which are to a large extent subconscious and so more likely to pass un noticed. A teacher of law does not need to search far to illustrate this point. Indeed it would be surprising if he did, since he may be said to begin the process in his own profession. Part of the task of a teacher is to mould the thinking of professional students along traditional lines. Put more starkly it is to ensure deviation from †̃¿ commonsense' towards a properly structured approach that is the result of decades of professional experience. Even the most radical teacher will be more effective if he puts forward his ideas within that mould. The iconoclast has to seek a different audience, his fellow professionals will fail to grasp much of what he is saying. Examples are easy to find. Early in the course on the law of contract the student will be told that goods placed in a shop window are not offered for sale. In law the intending purchaser enters the shop and makes an offer, rather than accepts one. Thus the shop keeper retains a right of refusal to sell. In legal jargon, which both hides and heightens the special mode of thought, goods in a shop window are †̃¿ an invitation to treat'. The law has good and sufficient reasons for this rule. Everything in a shop window is not necessarily