The Hollywood actor, writer, director and producer Ben Stiller has made a successful filmmaking career out of one staple ingredient: the loveable loser. Of course, Stiller's underdog tends to come out on top in the end, which is one of the reasons why his movies appeal to so many filmgoers. One of his most recent efforts, Tropic Thunder (2008), may not be his best work, but it does raise, albeit briefly, a crucial point about human nature.

Stiller's character in the film, Tugg Speedman, is an actor whose career is in decline. The final trigger of Speedman's downfall is his portrayal of a mentally-disabled man in the film-within-a-film Simple Jack. During a short tête-à-tête with one of his fellow actors, Kirk Lazarus (played by Robert Downey Jr.), Speedman is advised of the dangers of playing a person with serious learning difficulties. Lazarus points out to Speedman that other mentally-disabled fictional characters, such as Tom Hanks' Forest Gump (Forest Gump, 1994) and Dustin Hoffman's Raymond Babbitt (Rain Man, 1988), possess certain qualities which turn them into success stories. However, Speedman's Simple Jack is far too near the mark for Hollywood to

bear - hence its failure.

Now, whatever you may think of Stiller's satirical production, the scene in which Lazarus offers Speedman some apparent wisdom is striking, if not to say disturbing, because it touches upon a human attitude which reaches far beyond the rarefied climes of Sunset Boulevard. In short, there are some aspects of our fellows which many of us would prefer to see swept under the carpet.

In Tropic Thunder it is the proximity of a learning-impaired character which offends the sensibilities of Speedman's public. But Stiller's film alter-ego might have chosen any number of attributes which make the general public squeamish and found one and the same reaction.

The realities of minority conditions such as profound mental disability and mental illness, severe facial deformity and extreme old age are each tackled with kid gloves - even extreme poverty is only ever wheeled out when it's time for the annual charity drive and our consciences are pricked. After all, in the seemingly glossy, blemish-free environs of the