CMV: There is absolutely no scientific reason to think that (non-human) animals are conscious but plants are not.
By 'consciousness' here, I mean the subjective experience of qualia that humans seem to have. Famously, there is no scientific consensus on what this is, or how it arises; some people think it is an illusion caused by a certain kind of information processing, some think it's a feature of the universe that we just haven't scientifically described yet.
A lot of the average person's intuition about consciousness is not scientifically verifiable. Many of us feel like consciousness must be associated with intelligent behaviour, or self-acknowledgement, or even brains - but because we can't scientifically isolate consciousness, we actually can't find any of its correlates.
For many people, it's intuitive that actions are immoral if they harm a conscious being. Harming an inanimate object isn't the same, because it doesn't cause a conscious subjective experience of pain. So a lot of arguments against things like animal agriculture revolve around the idea that animals are conscious, presumably with the implication that plants aren't conscious so we should farm them instead.
But increasingly, it's being shown that plants do exhibit complex chemical responses to things that happen in their environments. They have self-preserving behaviour; they organise their resources to avoid being cut, injured or malnourished. This is fundamentally the same thing that animals do, even if the surface-level behaviour is different.
Animals react to harm in a similar way to humans (because we are related to them), but plants react to it in their own way. Given that we actually don't know how to diagnose consciousness in things, for all we know, plants might be having an intense subjective experience of pain when they're harvested.
This may feel like some kind of dodgy argument based on weird technicalities, but I mean it sincerely. I think plants are just as likely to have conscious experiences of pain as animals are, and I think we narcissistically assume only animals feel pain because they express it in the same way that humans do.
I am personally a vegan for environmental reasons, and am not trying to argue against veganism in general. I am also not specifically arguing that animals aren't conscious, or that plants are. I'm just arguing that the seemingly 'obvious' distinction we draw between them is based on vibes rather than science.
I know I worded this kind of bluntly just because I didn't want the post to be too long, but I'm genuinely interested in hearing where other people's reasoning leads them on this :)