I'm fairly puzzled by sensation/qualia. The idea that there's some chemical reaction in my brain which produces sensation as a side effect is very weird. In principle it seems like you ought to be able to pare things down in order to produce a "minimal chemical reaction" for suffering, and do "suffering chemistry" in a beaker (if you were feeling unethical). That's really trippy.
People often talk about suffering in conjunction with consciousness, but in my mind information processing and suffering are just different phenomena:
* Children aren't as good at information processing, but they are even more capable of suffering.
* I wouldn't liked to be kicked if I was sleeping, or blackout drunk, even if I was incapable of information processing at the time, and had no memory of the event.
So intuitively it seems like more neurons = more "suffering chemistry" = greater moral weight. However, I imagine that perhaps the amount of "suffering chemistry" required to motivate an organism is actually fairly constant regardless of its size. Same way a gigantic cargo ship and a small children's toy could in principle be controlled by the same tiny microchip. That could explain the moral weight result.
Interested to hear any thoughts.