I thought that Imposter was interesting for the points that it raised and as a story, but I think that it had some plot holes. For one thing, if these aliens are capable of using a U-bomb the size of a person to apparently destroy a world, why didn't they just send one in a probe to earth to blow it up. Also, if they thought that Olham could be set off by a verbal phrase, then why did the officers arresting him talk to him?

Even if it did take a contrived plot to do it, I think that Dick did raise some good questions. Really, I think that Olham's situation is the ultimate conflict of interest. On the one hand, he wants to protect himself, and even more, his entire mental conception of who he is. On the other, one would think that, at least if he took Peters and the others seriously, he would want to protect humanity from destruction. Considering what people will do in extreme situations, I suppose that it is rather realistic that he would refuse to consider that he might be a robot-bomb at first, though. One would really have to emotionally detatch oneself from that situation in order to deal with that realization without going insane. Then again, he would have to consider the possibility that his mental processes were changed by the aliens, so maybe he cannot even trust them- and if he cannot trust himself, others, or anything that he thinks- that he can think- than what can he do?

P.S.- sorry about posting this late, but I lost my copy, couldn't find the text on the internet, and spent about an hour looking for it until I finally found it.