In the years since Roger Rabbit, there have been many technical breakthroughs in representing the solidity and texture of the non-existent - the ghosts in last year's relatively workaday Casper had a more palpable aura than anything Bob Hoskins encountered in Zemeckis's movie. Toy Story makes life difficult for itself, though, by choosing to show us two worlds - the human world and the world of toys - through the same medium.
Flesh is still beyond the animators. Scud the dog has dead eyes. The kids in the film have toy hair, as if it was made of individual rooted strands of plastic fibre. If you shook their hands, it looks as if you would leave squish-marks and pressure dimples. The mother in the film is a trim statuette of walking dough - her gait shows none of the visual polyrhythms of human progress.
Better, perhaps, to have taken the Tom and Jerry route and shown only fleeting details of the people; though the story, given to director John Lasseter by the writers - enough writers for a law firm, Whedon Stanton Kohen and Sokolow - demands a final confrontation of the toys with Sid the bad kid. This scene, with deformed toys taking revenge on their torturer, suggests that at least one member of the law firm is an admirer of Tod Browning's Freaks.
When it stays within the world of the toys, Toy Story is utterly assured in its flicking back and forth between the modes of adult and childish pleasure. When Mr Potato Head expresses his contempt for the Slinky Dog subservient by pulling his lips off and applying them derisively to his own undivided potato buttock, adults will smother their giggles in the presence of children, while children will feel free to laugh hysterically, knowing they can't be criticised for being amused by naughtiness not expressed in language. Anyone who shushes them has to explain the joke.
The adult references in the film are delicately managed, and don't exclude children. Woody the Cowboy (splendidly voiced by Tom Hanks) finds himself at one point in an arcade game inhabited by squashy three-eyed aliens, who have built a religion round the Claw that comes down now and then to pick one up. The chosen one makes speeches of devout hope as it is winched away from its fellows. When Woody is chosen, and resists, he shouts to the aliens who drag him back to the Claw, "Let go, you zealot!" - a single sophisticated word giving an extra comic spin to the situation.
There are human verities that animation can't easily inhabit, and for which it struggles to find equivalence: sex and death. In Toy Story, Woody has a synthetic crush on Bo-Peep, but that isn't it. Sex (at least in its aspect of longing for fulfilment in union) and death are both defined by the film in relation to the toys' owner, Andy. To be Andy's chosen toy is to experience fulfilment in union, to be superseded in his favour is toy death. Woody has Andy's name written on the soul of one boot, and his place looks assured, until Buzz Lightyear arrives one birthday.
In the course of the story, Woody sins against toy solidarity by trying to eliminate the competition, and is redeemed by a deeper understanding of it. Along the way, though, Tom Hanks gets to express vocally what must be to him, the big screen's Mr Nice Guy, a gratifying quantity of pettiness and rancour. Meanwhile, Buzz must accept his own limitations. He isn't really an astronaut. He can't really fly, though plausible wings flick out of his shoulders at the touch of a button. Buzz discovers these things when he happens to see an advertisement for himself on television. Now he knows why, when Woody pummels his head, it lets out that tell-tale squeak of inauthenticity.
This is a nice cod-existential moment, not overplayed. Buzz briefly despairs, and when he is adopted by a little girl and recruited into her genteel tea party games, he accepts his new identity as Mrs Nesbit. Only gradually does his self-esteem return, and the knowledge that toys, too, have a purpose.
Oddly, the film's score, by Randy Newman, is intermittently as mushy as what he wrote for Awakenings. For someone who writes rather dry songs, and delivers them in a cracked drawl, his writing for orchestra is weirdly hushed. Toy Story includes some of his singing, to bizarre effect - nothing could seem more incongruous than the apparition in this techno-shiny world, of the roughest vocal cords in the business.
In the eternal triangle of boy and toys, only the apex is exempt from the imperative of personal growth. Andy has nothing to learn. This should be a cause for celebration, in the overwhelming didactic world of children's cinema, but the inertness of Andy in his family situation is a troubling flaw of the film. Can Toy Story be a great kids' movie without including anything of children's experience?
The film starts with a birthday in one house and ends with Christmas in another, but we never learn the reason for the move or its meaning in social terms - is it a move up? down? inwards? outwards? Above all, one word is never mentioned by Andy or his mum, even at those family festivals. The word is dad.
Is dad dead, divorced, away on business? All three? Or were Andy and his drooling little sister raised from pods? Andy's family life has no feeling-tone. It's completely neutral, and this may be the strangest innovation of all in Toy Story. There was a time when Disney films showed us families that had no characteristics apart from being luminously normal. Now Disney shows us a family that has no characteristics, apart from the fact that it's not.