Tom Stoppard's work has been notably generous with many commodities, from verbal wit to metaphysical ennui, but with one it's always been notably stingy. Bluntly, his characters have lacked strong personal feelings. A sort of rueful tristesse has, on the whole, been their dark night of the soul. It was in that mood that both the philosopher-hero of Jumpers contemplated the disloyalties of a wife he was supposed to love and, rather earlier, Rosencrantz and Guildenstern shrugged and joked their way to their violent deaths. Something deeper was perhaps touched in Every Good Boy Deserves Favour, Stoppard's tale of a father and son separated by KGB malice; but only a bit, and briefly. You can't conceive of his people in any sort of ecstasy, whether of pleasure or pain. You can't imagine them exulting or howling or even hurting very much.

Or couldn't until The Real Thing, a play in which Stoppard put his talent on the couch and subjects it to some courageous scrutiny. This begins as if nothing has changed. A husband urbanely quizzes his wife about her professed trip abroad. Franc doing well? Frank who? The Swiss franc. After a bit more verbal virtuosity he reveals that she left her passport at home, and the curtain falls on her mild dismay, his suave amusement at this proof of her adultery. It is an amusing piece of self-parody on Stoppard's part, and it is promptly rejected with something akin to self-disgust. What we've been watching, it seems, is a scene by a dramatist noted, like Stoppard, for his wit, sophistication, intelligence, and general lack of commitment, either political or emotional. His life, into which we're plunged for the rest of the evening, turns out to be considerably less bland and brittle than his art.

Henry, as he's called, begins an affair with an actress, Annie. She tells her husband she's leaving him, and his reaction is abject and embarrassing: 'Don't, please don't.' Then Annie, now married to Henry, sleeps with an actor, and it's the dramatist's turn to wail and implore like a stricken child: 'Please, please, please don't!' Here is scintillating Stoppard, unstoppable Tom—intellectual trapezist, juggler with words, up-market acrobat and clown, a big top in propria persona admitting that love hurts, hurts hideously. On the face of it, it's a conversion as astonishing as if Phèdre were to frolic onstage in cami-knickers, high-kicking and singing 'that's my baby'.

On the face of it. Let me not suggest either that Stoppard's earlier work is essentially frivolous—what other dramatist worries so earnestly yet entertainingly about the moral nature both of ourselves and of the dark, bewildering universe we glumly inhabit?—or that this piece is woozy with untidy, unfunny emotions. Its recognition that people have hearts and glands doesn't prevent them also having agile wits to exercise. Nor are their emotions, genuine though they seem, the sort that yank painfully at our own sympathetic heartstrings. To make a distinction of Stoppardian nicety, this is less a feely play about thinking people who feel than a thinky, a very thinky, play about feeling people who think. Songs and literary references—for instance to Miss Julie and 'Tis Pity She's a Whore, in both of which Annie is performing—appear in deft counterpoint to the often contradictory evidence provided by the characters themselves. What is this 'love'? Is commitment, personal, political and/or artistic, possible or desirable? Are there any values at all? Question after question emerges from Henry's professional and domestic circumstances; and, since this is a deceptive world of dramatists, actors and plays-within-plays, and (moreover) a world that has itself been invented by a master-illusionist named Stoppard, there are few firm answers, and conceivably no 'real things' at all.

And yet, for all this calculated uncertainty, the piece does reach, or seem to reach, two conclusions. The first is that love exists. Why else (a recurrent image) the obsessive rummaging through others' belongings in search of evidence of betrayal, why else the pain and intermittent delight? The second is, in Henry's words, that 'public postures have the configuration of private derangement', or, to put it more temperately, that political attitudes reflect purely private motives. For much of the evening, to be sure, this is as much a subject of debate as the reality of love. To explain. One of Annie's protégés is a soldier imprisoned for violently protesting against nuclear weapons. He has written an autobiographical TV play that is artistically abysmal but indisputably 'committed'. Annie wants Henry to revamp it, and he does so, though he despises it. Is this another step forward in the dramatist's moral and emotional education, proof that he can give himself to a cause as well as to a person?

No. Not a bit of it. It serves only to 'prove' the point about the phoniness of political motives. The soldier made his protest to ingratiate himself with Annie; Annie supports him because she feels guilty; Henry helps them because he loves Annie. These, anyway, are the play's final revelations, and their inference leaves me boggling. Am I deranged when I wonder if it's morally acceptable to aim H-bombs at Moscow? Is Tom merely sublimating childhood feelings of rejection when he writes indignant plays about the abuse of human rights in his native Czechoslovakia and elsewhere? Must we dismiss the campaigns of, say, Wilberforce, Silverman and Sakharov as emotionally dishonest 'postures'? It surprises me that Stoppard, who queries so much, should not have found a way to introduce questions as basic as these. It astounds me that, after flaying both his protagonists and (surely) himself with so many sharp-edged doubts about their adequacy, he should end by enshrining a cynical fib.

Still, that by no means sums up the final effect of the piece as a whole. Stoppard has said that the logic of his plays is 'firstly, A, secondly, minus A', with rebuttal following argument and counter-rebuttal that rebuttal, and that his aim is to 'dislocate an audience's assumptions'. Well, I can report that my intellectual bones were satisfactorily wrenched from their sockets by The Real Thing, and also that its algebra sometimes infected me with that hopelessness I felt years ago in the exam hall, when I was busy failing additional maths at O-level. If accusing critics can make dramatists feel inadequate, as this play implies, dramatists in their more Pirandellian moods can make critics feel the same. Yet, if it's a slippery, elusive piece, it's also one that kept its audience audibly amused at the time, and one that, in defiance of the usual rules, somehow manages to expand yet clarify in the mind afterwards…. [Stoppard has done much] to reconcile his old writing self with a new one. He has retained his humour, increased his complexity, and deepened his art.