Peter Sellers plays an idiot. However, after a string of misconceptions he is hailed as a wise man. The film is not as incomprehensible as the story appears in outline, and by the end of the film, when he is heading up a major corporation, it's somehow believable. A lot of the believability is because of astutely observed scenes, illustrating how easily we can be fooled. For instance, Sellers is holding court at a fancy party and people come up and question him, as you would a wise man, and he gives himself away - saying, "I don't read" - and they take this as meaning that one shouldn't read. Via these instances, he becomes the man others perceive him to be.
Ashby is my favourite director. Since I was a young man he has been a hero of mine; his whole body of work is stunning, Harold and Maude and Coming Home would be on my greatest film list.
Peter Sellers is another connection between these films - and I am a big Sellers fan - but they are also similarly themed. The film shows the end of the world, when a paranoid US general goes truly over the edge. Sellers plays three roles, including the US President. And despite the serious anti-war message, it is a humorous film. Sellers was one of the great, great comic actors. Centred around conflict, nuclear war specifically, the ridiculousness of miscommunication is laid bare.
Issue-led and issue driven, both directors treat their respective issues with energy. The films are filled with interesting, quirky characters, so making a mockery of them is all the more fascinating. War and false worship are in no sense admirable but both films have perspective: it could be you who is fooled.
Don't take anything at face value is the message. And don't prejudge for your audience: don't make direct fun of your characters, no matter how ridiculous, and ease the audience into the issues.