The exhibition begins with a clumsy proposition: a huge pink simulacrum of a woman's breast, for which the relentlessly crude soi-disant experimental artist Cesar is to be held responsible. Breast, 1966, may or may not have been inspired by the martyrdom of St Agatha. The amputated gland, hung on the wall like a stag's head in a trophy room, is certainly an extremely unpleasant object.
Moving briskly on, the visitor is invited to peruse old newsreel footage of the abdication crisis of King Edward VIII, playing over and over again on a television screen set into one wall of the gallery. He is there, presumably, as a symbol: the king who became a fool for love.
Nearby we encounter the 14th-century BC Pharaoh, Amenophis IV Akhnaten, or at least part of him - like the Cheshire Cat, he survives only as his smile, a pair of full and somewhat cruel carved lips, perpetually amused by who knows what. Perhaps the Pharaoh's stone mouth was included to suggest the sensual abandon of despotic rulers. An adjacent glass case contains additional incriminating evidence in the form of a marvellously wrought object said to have been commissioned in the early 18th century by the erotomane Emperor Frederick IV of Denmark. It is a pocket-sized box in which lurks a tiny spring-mounted phallus and testes, ingeniously modelled in gold and mother of pearl.
"Amours" is not quite the life-enhancing celebration of love and lovers promised by its chief organiser, Herve Chandes, in his preface to the catalogue. There he writes: "Whether they are the details of a body or face; representations of a couple entwined; static emotions; angry gestures; happy or restrained ... the works do not tell a story, do not pigeonhole the story of the emotion of love according to taste, mores, fashion; they express love as a surprise, a light-headedness, a fulfilment."
Making allowances for translation (and further allowances for the fact that the majority of essays in French catalogues of this genus are written in a language that few Frenchmen would recognise as their own), it has to be said that this is untrue. For one thing, the assembled works reflect infrequently on love and much more often on sex - which is not, of course, always quite the same thing. For example, the exhibition contains some of Henry Fuseli's early 19th-century erotic drawings, which are documents not of affection but of an imprisoning masochistic sexual fixation. They are distressingly (or arousingly, depending on your perspective) single- minded in their depiction of the nature of the painter's fantasy. One drawing in particular sticks in the memory: a small but concise picture of an elaborately coiffed young woman, leather dildo strapped to her waist, energetically sodomising a bound man.
This picture has been hung in an out-of-the-way corner of the exhibition, a corridor-cum-cul-de-sac - perhaps because it is precisely the kind of work of art that contradicts the airy-fairy libertarian rhetoric in which "Amours" has been bathed. The pointed plurality of the exhibition's title - not Love, after all, but Loves - implies both a cosily liberal view of sex and a lurking didactic intent. The implication is that anyone who is narrow-minded enough to believe that there is just one right way to love another human being need only come to the Fondation Cartier for a corrective course in sexual tolerance. Confronted by touching images of Lesbian Love (a blurred photograph by Cartier-Bresson of a pair of young Mexican girls embracing naked on a bed), of Gay Love (Robert Mapplethorpe's Charles and Jim 1974), of Black Love (Seydou Keita's portrait of a husband and wife in Bamako, Mali), we will all throw off our mind-forged manacles of prejudice. We will become happy, healthy members of an emancipated and enriched commonweal that embraces the broadest possible range of human sexuality.
This seems unconvincing partly (but only partly) because of the opportunistic flavour of the entire enterprise. The organisers appear to have been rather too happy to exhibit more or less whatever they could persuade various private owners and museums to lend them, regardless of the effect that this might have on the coherence of their exhibition. One consequence of this is that "Amours" ends up amounting to considerably less than the sum of its parts. Fragonard's drawing, The Lovers' Bed, is a summary masterpiece of rococo eroticism, showing us an unmade bed with sheets that billow like clouds, and sketching, by implication, a fantasy of being light enough to inhabit such a place - a dream of being as light as a feather, as weightless and malleable as a rococo god or goddess supported on painted clouds. There is little to be gained, however, and no new insight into Fragonard to be derived, from seeing such a work placed arbitrarily in the same company as Sophie Calle's recent still-life photograph The Erection, or Andy Warhol's Black Hearts (a late Warhol that is more playing-card than love letter).
The main flaw of "Amours" is the yawning gap between the moral which Monsieur Chandes would have his audience draw from the exhibits that he has selected - the half-hippy sentiment that there is room enough in this world for many kinds of loving - and the actual effect of the exhibits themselves. Fuseli's drawings embarrass his thesis precisely because they do not "express love as a surprise, a light-headedness, a fulfilment"; they envisage desire, rather, as a compulsion. As Fuseli knew too well, the fact of sexual difference is not necessarily a cause for celebration, and sexual desire in all its multiplicity has plenty of hateful aspects. In Susan Sontag's words (from her fine essay The Pornographic Imagination), human sexuality is "a highly questionable phenomenon... one of the demonic forces in human consciousness".
The uneasiness at the core of "Amours" is best encapsulated, perhaps, by the difference between just two of the exhibits. Near the entrance to the show, a short film by Andre Bonzal called Gate 4 - expressly commissioned for the occasion - is being projected on a continuous loop. We see a group of people, some black, some white, some young, some old, waiting in an airport. They look tense, sad, weird, dysfunctional. Then those for whom they have been waiting - their lovers, wives, husbands, children - arrive, and they rush to meet them. They hug. They smile. They are restored to humanity.
Turning away from this short and touching parable about the unifying power of love, we are instantly confronted by a Picasso painting of 1931 called The Kiss. A cartoon couple (but more sinister than comic) are not kissing so much as eating each other's faces. Their tongues are red daggers. Picasso recognised that desire is often inseparable (it certainly was in his case) from the desire to conquer and absorb others. He knew how savage, how unacceptable, how unsociable love can be.
`Amours' is at the Fondation Cartier, Paris (00 331 42 18 56 50) to 2 Nov