Quote:
Originally Posted by CSflim
A plant does not have a central nervous sytem or a brain. There is no reson to believe that it is sentient. Sentience is a necessary condition for pain, hence there is no reason to suggest that plants feel pain.
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Define pain in an usefully observable way.
It's all well and good to look an the non-human analogue of pain receptors and observe how they respond to stimulation. But it does not follow that a more intense response in those neurons translates directly to a more intense sensation of pain in the animal's brain. Many anesthetics work by attenuating nerve signalling so that a pain signal fades out prior to reaching the brain. If we observe the nerves at the site of a surgery, it would look to be excruciatingly painful. But the signals never reach the brain to be converted into pain.
Aside: Formerly, anesthetics also functioned as paralytics. To decrease recovery time, and to lessen the dangers of anesthetic use, doses are decreased and more modern localized anesthetics are used. This has a problem in that signalling might not reach the brain to be percieved as pain, it may still be sufficent to trigger a reaction in local tissue or a spinal bounce reflex. So, often a paralytic is given in concert with a lowered anesthetic dose. Now, go read some of the stories about where they miscalculated the anesthetic dose, but got the paralytic dose correct.
If we define "experiencing pain" as aversive reaction to damaging stimuli, we have a pretty good fit for spotting painful things... though, technically, someone chemically paralyzed on an operating table with no anesthetics isn't expereincing any pain by this definition. Further, certain plants DO present aversive reaction to damaging stimuli... though on a predicably slow timescale.
Which leads us to another interesting question. Maybe cutting a flower is excruciating for a rosebush, but because we observe no physical reaction on an animal timescale we assume plants are insensate. A number of plant species are also known to release chemical signals in response to damage, infection, and/or infestation. Neighboring plants may then respond in way to reduce their own chances of being infected or infested or the severity of such an attack. Hmmm.
This is totally aside from the fact that many people simply don't care if it's painful for a cow to be made into tasty steaks.