I actually tried to explain what you can measure beyond simply "pain" (noxiception) about suffering. Because like you said, noxiception is present in many organisms and in many cases it can be (IMO very reasonably) argued they are simple stimulus-response mechanisms (without moral value), while in other cases (say, a dog suffering) it can be (also reasonably) argued that there are more complex things going on and morality comes into play.
The question is where to draw the line, which is hard. But you can estimate bounds of what constitutes suffering. I agree that merely having a specific response to a noxic stimulus isn't suffering. But I do believe that the fact that you can (long-term) damage the learning ability of a snail by applying otherwise non-harmful (but painful) stimuli, is something that at least to me comes awfully close to what I'd consider psychological trauma in a human. So it's not really a matter that it responds to some stimulus (like plants), but that the way in which it does shows a higher level function that to me seems somewhat analogous to how we suffer.
Doesn't tell me where exactly to draw the line, but does give me a clearer picture somewhat, at least leads me somewhere further than simply "does it have a pain-response?".
I actually tried to explain what you can measure beyond simply "pain" (noxiception) about suffering. Because like you said, noxiception is present in many organisms and in many cases it can be (IMO very reasonably) argued they are simple stimulus-response mechanisms (without moral value), while in other cases (say, a dog suffering) it can be (also reasonably) argued that there are more complex things going on and morality comes into play.
The question is where to draw the line, which is hard. But you can estimate bounds of what constitutes suffering. I agree that merely having a specific response to a noxic stimulus isn't suffering. But I do believe that the fact that you can (long-term) damage the learning ability of a snail by applying otherwise non-harmful (but painful) stimuli, is something that at least to me comes awfully close to what I'd consider psychological trauma in a human. So it's not really a matter that it responds to some stimulus (like plants), but that the way in which it does shows a higher level function that to me seems somewhat analogous to how we suffer.
Doesn't tell me where exactly to draw the line, but does give me a clearer picture somewhat, at least leads me somewhere further than simply "does it have a pain-response?".