Radiohead songs aren't meant for line-by-line translation/interpretation as if there were a hidden meaning; rather, the goal is to directly communicate to the listener the profound experience of some particular mental state. In this case, there's nothing more specific going on than a person who is experiencing the greatest depths of emptiness but who just can't bring himself to declare with certainty that the optimists are deluded. Maybe there is hope for something better after all.
Radiohead songs aren't meant for line-by-line translation/interpretation as if there were a hidden meaning; rather, the goal is to directly communicate to the listener the profound experience of some particular mental state. In this case, there's nothing more specific going on than a person who is experiencing the greatest depths of emptiness but who just can't bring himself to declare with certainty that the optimists are deluded. Maybe there is hope for something better after all.