Is there much point in getting to the bottom of things? Some people think that is what education is ultimately for, or at least ÖйúAƬ, and they can be startled to hear it questioned. So Cambridge audiences may once have been surprised to hear Sir John Clapham (1873-1946) launch a series of lectures, just over a century ago, on British economic history.

They were published in three volumes in his lifetime, and after his death there appeared A Concise Economic History of Britain from the Earliest Times to 1750 (1949), which began in arresting style: "Of all varieties of history, the economic is the most fundamental." You imagine him pausing for breath - he was about to say something astounding: "That is why it is dull." Nothing, after all, is interesting because it is fundamental. "Foundations exist to carry better things."

There is nothing unusual about a professor writing a dull book. It is highly unusual, however, to announce it. On the other hand Clapham always saw himself as a political historian, and it is clear why he chose to write about economic history. It was because he had been told to do it.

In 1897 Alfred Marshall in a letter to Lord Acton remarked that the lack of an economic history of Britain was a disgrace, and in the 1920s and 1930s Clapham duly published three bulky volumes on British economic history since the 1820s. So his posthumous book on earlier times was what would now be called a prequel, and it announced at the start something he had always believed - political history mattered most.

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The centenary of Clapham's lectures passed last year without notice, as did the centenary of the start of Herbert Henry Asquith's long premiership and the creation of the British welfare state. If Clapham is mentioned at all these days, it is probably with a patronising murmur about British empiricism.

Like Acton, Clapham believed in finding empty spaces in the past and dutifully filling them, so he was probably a connoisseur of tedium, and he is said to have died of boredom on a late train back from London as he shared the compartment with the wife of a college master famous for the sedative properties of her conversation. "Not a mark on his body," the medical report is rumoured to have said, "but with a terrible staring look in his eyes." The story is a tribute to the lady, for Clapham must have been a hard man to bore.

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On the other hand, his last book opens with a statement of lapidary weight: "Foundations exist to carry better things." A basement, after all, is likely to be the dullest place in the house, with windowless walls, although in the US they are called English basements if they open on one side to the sky. I once lived in one in Greenwich Village. You could see skirts and trousers from the front window, but it was still only a view from the basement and, on the whole, you wanted to get out and see New York.

It is easy to forget that it can be a good idea to ignore foundations and take them for granted. A concert musician has better things to think about than where to put his fingers, and the skilled artisan may find it so difficult to explain that he shows you what he does rather than tells. Words alone are certain good, said W.B. Yeats, but he would not have said that of cooking a meal, riding a bike or making love. Speaking a native language, similarly, may call for little reflection - so little that you can confidently begin a sentence without being sure how to end it. It is erroneous, Alfred North Whitehead once remarked, to say that we should always think about what we are doing. That was in An Introduction to Mathematics (1911), which he wrote at much the same time as Clapham's lectures. He believed the reverse was true. Civilisation advances by extending the number of things we can do without thinking. "Operations of thought are like cavalry charges in a battle - they are strictly limited in number, they require fresh horses, and must only be made at decisive moments."

That echoes Hamlet's celebrated remark about thinking too precisely on the event: "A thought which quartered hath but one part wisdom, And ever three parts coward" (IV, 4).

In the last scene of the play, he fulfils his duty to a murdered father on a sudden impulse. Killing Claudius in hot temper solves nothing, some critics have suggested, but they exaggerate. It discharged a sacred promise, it relieved Denmark of a tyrant, and it presumably appeased the shade of a murdered father. That solves a good deal. It was an impulsive act, but why not? Some impulses are good, after all, some are heroic, and you can think too deeply and too much. Those who discovered DNA half a century ago were not even looking for the secret of life, as James Watson tells in The Double Helix, but it is not in doubt that Francis Crick, Watson and Maurice Wilkins all deserved their Nobel prize.

The vogue for Grand Theory faded a generation ago not because its foundations were seen to be insecure but because no foundations were found.

No stated and agreed foundations, that is, and it goes without saying that they would be of no use unless they were stated and agreed. No use saying you know but cannot tell; no use, in any case, unless your view is widely accepted. Hence the mood of resigned bafflement that haunts literary studies in our times. A London cab-driver, on recognising Bertrand Russell, remarked: "You're a philosopher - what's it all about?" and the story is sometimes told to first-year students to moderate the extravagant expectations of youth.

Perhaps they should be reminded too of Hamlet's soliloquy, or of Orsino's embassy in Twelfth Night where Olivia, the cruel fair, mocks Viola: "Item, two lips, indifferent red; item, two grey eyes, with lids to them" (I, 5).

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Everyone knows beauty cannot be inventoried. To make a list is to make fun, and the butt of the joke is anyone who confuses knowledge with account-giving. You know Olivia to be beautiful not by describing her or by naming the criteria of beauty but by looking at her.

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It does not follow that accounts should never be given, even of love. It can relieve pain to make mock of it, even the pangs of love. Clapham's paradox, and Whitehead's, may be taken further. The search for fundamentals may be boring, but boredom can be consoling and even salutary. Any advanced intellectual inquiry is likely to have its longueurs, in any case, and that is not in itself an objection to attempting it.

Aristotle had an answer to the bafflement of modern critical thought, and oddly enough it is not in the poetics but in the physics. In Book Two he praised the silent possession of habitual knowledge (heksis) - wordless knowledge born of experience, like a cyclist on his bike, a concert pianist at the keyboard or anyone cooking a familiar dish in the kitchen. No full account can be offered in such cases, but then none is needed. An occasional remark can still help. I once heard a grandmother explain that she added sugar after stewing fruit to avoid caramelising. I was too young to understand the word and still do not altogether understand it. But I took the advice, which was theoretical, because it was confidently offered by an experienced cook, and that is surely a sufficient reason.

All of which leaves Russell's cabbie nowhere, and Grand Theory is in much the same place. It flourished a generation ago in Paris and at Yale, and there are rumours it later took refuge in suburban Los Angeles and in even remoter places, dropping out of vogue not because it was implausible but because it was boring. No literary activity can afford to be boring, and criticism has long been a kind of literature.

Samuel Johnson demonstrated it more than two centuries ago when in the last years of his life he wrote The Lives of the Poets - an enduring masterpiece that has lasted better than his poems, his only play and his solitary novel - and critics have laboured ever since under the double obligation of writing well and looking acute at the same time. No scientist has to worry about both, and theorists like Jacques Derrida who thought nothing of lecturing for several hours at a stretch were always likely to start a bolt for the door even before they had uttered the dread word Deconstruction. People did not want foundations. They wanted a penthouse view.

Worse still, the foundations proved to be nothing of the kind. Those on the prowl for the stated and agreed foundations of literary judgment were the victims of a brutal paradox, since any formula could be sustained only by something other than itself. What lies under the basement?

So the search for foundations was conceptually as well as practically impossible. Self-exempting claims are always self-refuting, and the assumption that all truth-claims, in the last analysis, need theoretical justifications easily refutes itself.

Reports of the demise of Grand Theory, however, are probably exaggerated. There will always be those like Russell's cabbie who want to know what it is all about. That demand is implicit in the pace of modern life. When you touch a switch you expect the whole room to light up at once, and generations brought up on that expectation are not to be fobbed off by reading Clapham, Whitehead or anyone else. They will want and demand starkly simple solutions.

Marxists and National Socialists once offered that and, since their spectacular failure, hardly anyone believes that history is class war or that it is all the fault of the Jews. That offers those who teach literature a chance worth taking.

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We live in a fortunate age where contending ideologies have called a truce, where problems are welcomed because they are complex and solutions doubted when they are simple. It is a moment of hope. The world, in any case, would be duller as well as nastier, as anyone can see, if the view from the basement had been proved right.