Maybe this is a dumb question but did each person write their own piece entirely or was there a set script?
Namely I'd like to know if Ryan Powers, the guy who is autistic in real life wrote what he said in the film. His scene is one of my favs. It's the one where they're walking in circles on the rooftop and he's talking about how a thousand years is but an instant and there's nothing new it's all the same pattern over and over.
The "Written By" credits in Waking Life are inaccurate. Linklater wrote all the dialogue for Wylie, himself and his daughter, however the authors of the dialogue for the other characters were often the individual cast members...sometimes writing in collaboration with Linklater, or sometimes writing the entire part themselves. Linklater wanted to acknowledge their writing contributions but the Writers Guild of America would not allow him to list them in the film's credits. Although he was furious about it, and somewhat embarrassed, there really wasn't much he could do. Rules is rules and the WGA is a stickler when it comes to this stuff.
The info was from an Austin Chronicle interview with Linklater.
There's a bunch of reasons behind the Guild's rigidity on this stuff. A lot of the rules seem driven by money, which isn't surprising. Wikipedia has a decent entry on the WGA screenwriting credit system:
Well the Alex Jones bit definitely sounds like Alex Jones wrote it. I sort of understood it that all the philosophers/characters wrote their own dialogue, maybe not in screenplay form but yeah.