I'm with Kaj on this. One man's modus ponens is another man's modus tollens. I don't mind counting frogs or cows as partially conscious to the extent they reconcile conflicting impulses, and I don't understand why you take such a viewpoint as a refutation of PRISM. Why is consciousness all-or-nothing, rather than a matter of degrees?
It's definitely a matter of degree, but I don't think that humans being more conscious is a result of being more able to reconcile conflicting impulses. I think of the refutation as more being in my second paragraph.
Imagine if a friend of yours suddenly somehow lost all control of their body except for their mouth. They do things, and have introspective access to why, and can talk about what they're doing, but take no part in actually deciding what to do.
I would still consider them to be conscious, and intuitively think that something that is more able to ...
One of the most important points raised by the sequences is that not all minds are like humans. In quite a few places, people have discussed minds with slight changes from human minds, which seem altogether different. However, a lot of this discussion has been related to AI, as opposed to minds created by evolution. I'm trying to think of ways that minds which evolved, and are effective enough to start a civilization, could differ from humans'.
Three Worlds Collide would seem like an excellent starting point, but isn't actually very useful. As far as I recall, the Babyeaters might have learned their baby eating habits as a result of societal pressure. The main difference in their society seemed to be the assumption that people who disagreed with you were simply mistaken: this contrasts to humans' tendency to form rival groups, and assume everyone in the rival groups is evil. The Super-Happies had self modified, and so don't provide an example of an evolved mind.
So here are my ideas so far.