> But you would have to redefine pain to ignore the experience aspect
No, it's the opposite. Plants clearly don't have the reactive aspect, but we have no idea whether they have the experience aspect, because we have no idea what causes experience or how it works.
We also don't know that consciousness provides an advantage to animals. We associate consciousness with intelligent response. But it may well be possible to have intelligent response without consciousness (e.g. like computers, although technically we can't be sure that they don't have consciousness either)
An intelligent response without consciousness is different to an intelligent response with consciousness. That is the re-definition.
We can speculate that the full human experience of pain may exist in the absence of a brain. And we can estimate the probability of that being the case in plants. Do you really think that probability is high?
Also, plants can and do react to damage and even touch.
No, it's the opposite. Plants clearly don't have the reactive aspect, but we have no idea whether they have the experience aspect, because we have no idea what causes experience or how it works.
We also don't know that consciousness provides an advantage to animals. We associate consciousness with intelligent response. But it may well be possible to have intelligent response without consciousness (e.g. like computers, although technically we can't be sure that they don't have consciousness either)