That Robin wrote well is something of which no reader of these pages will need any persuading. That he made fine public speeches is something that has also been much and rightly recalled since his death. But when I think about him now, I think of something else. I think of his ability, whether over a meal table, in a corner of a bar or just sitting in his office, as a talker.

Robin was fun to listen to, fun to talk to and, above all, fun to talk with. He possessed all the essential attributes of the good talker. He savoured the language, and he enjoyed his own facility with it. He drew on a wide range of literary and historical knowledge. But he also had perhaps the most important quality of all in a talker. Though his talk was not without the competitive aspect that is always part of the best conversation, he also possessed the enthusiasm to make talk a collaborative activity too. He had the instinctive ability to listen to the other person and to respond, not just on his own terms, but on yours too.

I had been thinking about this ability as a talker ever since the announcement that his funeral was to take place in St Giles' Cathedral. For the thing I distinctly remember about the cathedral from my previous visit, long ago, is the brass relief memorial there by Augustus St Gaudens of the bed-ridden Robert Louis Stevenson, pen in hand. Though this mention of Stevenson may appear a non sequitur, it is anything but. For if ever the world produced a prince and paragon of talkers, it was Stevenson.

We know this from his friends. Stevenson's talk was almost incessant, they recalled. As a student, he was already celebrated for his sparkling conversation. Later, visitors remarked that when he was on form he talked and laughed all the time. On the day of his death in Samoa in 1894, his biographer Jenni Calder writes, Stevenson was "bright with talk".

But the best evidence of Stevenson the talker comes from Stevenson the writer. Stevenson's essay Talk and Talkers, written in 1882, is a piece that makes one glad to be alive. When you read it, and though its author is a hundred years and more dead, it is as though a new friend, bursting with life and wit, has suddenly settled himself in a neighbouring armchair to delight you with a string of dazzling observations on the joys and rewards of good conversation.

To excel in talk, Stevenson says, is simply the best ambition we can have. It is both a private and a public accomplishment. Talk does not merely make us good company to our friends and family, he says, it also enables us to "bear our part in that great international congress, always sitting, where public wrongs are first declared, public errors first corrected, and the course of public opinion shaped, day by day, a little nearer to the right".

Yet talk must not be dismissed as an inferior, preparatory stage of human communication before an idea reaches its supposedly higher, written form. On the contrary, says Stevenson - and what an astonishing thing this is for a great writer to say - literature is but "the shadow of good talk", an imitation that falls "far short of the original in life, freedom and effect". While talk is always fluid and tentative and involves giving and taking, written words are fixed and dogmatic, as well as constrained by form and tradition.

"In short," argues Stevenson, "the first duty of a man is to speak; that is his chief business in the world; and talk, which is the harmonious speech of two or more, is by far the most accessible of our pleasures. It costs nothing in money. It is all profit. It completes our education, founds and fosters our friendships, and can be enjoyed at any age and in almost any state of health."

It is tempting for me to sit back and let Stevenson simply take over here, to piggy-back on his brilliance by summarising and quoting further large parts of this wonderful humanistic credo. But I have other points I wish to make, and you will have to read for yourself how sensitively he grasps that conversation advances on the basis of trust and tact, that it not only tolerates but encourages a certain ostentation, digression and allusion - "the whole flotsam and jetsam of two minds forced in upon the matter in hand from every point of the compass" - and that the profit of talk is not in being proved neatly right or wrong, but from the exercise itself and the unpredictable enlightenment that comes from the congress of minds.

Few of us can hope to talk like a Stevenson. Yet even to read his essay is to recognise that it is a guiding light. We develop and are educated partly by direct experience and partly by focused study, but particularly also by talking to others and by learning with and from them. Unless we talk, albeit mostly not with the fluency of a Stevenson or a Cook, we will never be truly educated - drawn out - or even, as the Victorians might have put it, improved. And a precondition of such talk, as Stevenson says, is that we must be prepared to "lay ourselves open", to be prepared to listen as well as to speak, to acknowledge that we do not know the answers before we pose the questions.

Bill Clinton used to see himself as a politician at the heart of what he called "the conversation". His was a conversation about many things - the role of government, the failure of world socialism, the persistence of inequality and much more - but at its heart was a recognition that wooden dogmatisms (Stevenson's phrase) provided no solutions, and that neither he nor we knew the answers to the questions that the conversation continually posed.

Some of my best friends work on the Today programme. Yet it seems to me that our public talk in this country is now being relentlessly drained of the elements that make such talk rewarding. Politicians, indeed, are now trained specifically not to answer interviewers' questions. Instead they are told to remain focused on making the predetermined points in the party "line to take". Their interrogators are no better, seeking little more than to hector, embarrass and oversimplify. The consensual creativity and freedom of true talkers, trusting and trusted, is wholly absent, almost wholly subordinated to egotism, adversarialism and melodrama.

Little or nothing now remains of the "great international congress, always sitting" of which Stevenson wrote so exhilaratingly and of which Robin Cook was one of the last exponents. The art of talking, the thing that makes human beings what they are, has become a refuge for recusants. Our public discourse has become unworthy of the name and will remain so unless and until we decide to change it. Maybe it is time we talked about it.

m.kettle@theguardian.com