Non-existence

[Jon Paul]

But that doesn't prove a neccessary causal link exists between brain activity and consciousness generally

It doesn't need to. There's not even any self-evidence of consciousness as a phenonmenon in itself. I have self-evidence that I'm conscious,

And that's all I mean with "consciousness", the fact of being conscious.

There's no evidence for consciousness existing as a phenomenon seperate to the brain.

Nor have I said that there is, or that there needs to be. Theres no evidence that there is a necessary causative link between the brain and consciousness. There is only the fact that I am consciously aware of my brains states, but that in no way proves a necessary causative link between brain activity and consciousness, which would have to be predicted by general principles and observational knowledge aside from conscious experience to be causally proven.

But if the concept of p-zeds is incoherent then other people have consciousnesses too, seperate to mine - otherwise I'd be conscious of them. So other minds exist apart from mine, and thus solipsism is erroneous.

That is not demonstrable given solipsism. It is only demonstrable given p-zeds because p-zeds is a naturalistic/realist ontology, and thus it grants the existence of an independently existing reality outside of the conscious experience of it.