> I don't know about _all_ animals, being agnostic on
> the insect sentience issue, but the howls of pain and
> expressions of fear that exist in anything more
> complicated than a lizard certainly seem evidence to
> me. And by the way plants do not possess central
> nervous systems.
This seems like an obvious example of anthropomorphism to me: "if we cry with pain when we suffer, then our psychological state must be about the same in animals when they cry." We have no way of knowing if this is true. My point here is not that suffering is a special state that humans experience; rather, I'm trying to point out that using common sense to determine whether or not X suffers is a thin reed upon which to base moral decisions.
Miles