We have no evidence that plants have consciousness, but then our only evidence that even other humans have consciousness is that they are somewhat similar to ourselves. We cannot detect it directly. If there were consciousness in the world that was significantly different to our own then we likely would be ignorant of it.
We do know that human consciousness has something to do with the networks of neurons in our brains. We know this because we can poke specific parts of it and manipulate specific aspects of our consciousness: we can observe a fairly direct correspondence between conscious experience and biological substrate.
To play devil's advocate: have a look at the way plants in a forest communicate with each other - even across different species! That's a complex network, in which individual plants could be analogized to neurons.
Do I think forests are conscious in the same way that we are? No. I do think "consciousness" is not a binary, and that we have poor tools and insufficiently-developed models for understanding it.
> We have no evidence that plants have consciousness, but then our only evidence that even other humans have consciousness is that they are somewhat similar to ourselves.
I don't have evidence I have consciousness. You assume you have it, but if you didn't what would really change? It's a made up word and the semantic value of the sentence "I have consciousness" is something like "I am special". Can you define consciousness in an objective way such that, were I to not have consciousness anything would be different for me?
It's the secular word for "soul", but at least the religious people have some ideas about what their woowoo nonsense terminology means.
> It's the secular word for "soul", but at least the religious people have some ideas about what their woowoo nonsense terminology means.
The fact that I experience anything at all (as opposed to being an unthinking being as we assume robots or machines to be) seems like something to me. I can't explain what it is, but it seems different to anything else I observe in the world.
> The fact that I experience anything at all (as opposed to being an unthinking being as we assume robots or machines to be) seems like something to me.
The roomba robot doesn't experience, it just goes through its routine. You're more sophisticated (a robot made out of meat), so the behaviors and internal state are more sophisticated. Your "experience" is just one of many illusions you are prone too. You can go look up some of them that it's possible for you to be aware of, they're pretty crazy.
The statement I quoted is just another wording of "of course I have consciousness!".
The fact that it's possible for me to be aware of anything at all is interesting though, and definitional of conciousness. It's possible the roomba's also experience things, but we generally assume that they don't.
This is entirely separate from whether one's perceptions are an accurate representation of reality, or whether one's experiences correspond to the parts of the brain that respond to things.
> The fact that it's possible for me to be aware of anything at all is interesting though, and definitional of conciousness.
"it's possible for me to be aware of anything" <--- restating your premise. Not evidence that your premise is true. Your definition of consciousness is circular.
Consider the slime molds, which have no brain, specifically Physarum polycephalum and Dictyostelium discoideum (you'll forgive me for conflating them a bit in this brief comment):
It can solve mazes. [0]
"They remember, anticipate and decide." [0]
They practice primitive agriculture: "they carry, seed and prudently harvest their food" (though no cultivation - what dummies!). [1]
And here's the kicker: "P. polycephalum ... spends most of its life as a single cell containing millions of nuclei, small sacs of DNA, enzymes and proteins." [0], but "When prey bacteria become scarce, Dictyostelium discoideum amoebae aggregate by the tens of thousands and produce a multicellular migratory slug that becomes a fruiting body in which about 20% of cells die to form a sterile stalk. The stalk aids the dispersal of the remaining cells, which differentiate into spores in a spherical structure called the sorus ..." [1]
Why do they have to have brains? Is it impossible that another structure could serve a similar purpose? Like, how long did it take us to figure out what brains are for?
They don't need to have "brains" in the sense that humans do, ie. discrete neurons and axons, but they do need to have "neural networks" - networks of nonlinear operators with a training mechanism. I'm aware of zero evidence that trees perform computation on a larger-than-single-cell basis.
You cannot direct growth at the scale of a single cell. There are many computations (based on hormonal gradients and other mechanisms) that occur at the scale of larger structures, such as leaves or branches. Of course, those mechanicisms are not going to create consciousness.