Good post, enki. I think Haldane and others are hitting up against something real - the so-called hard problem of consciousness. This could be crudely paraphrased as the problem of a physical organ (the brain), producing abstract thought, feelings of subjectivity, and in fact, experience itself.
The short answer to that is that we don't know how the connection between physical and mental works, but the longer answer is that neuroscience is busy looking for solutions. The so-called 'mysterians' argue that we will never understand the connection between the physical events and the mental events in the brain, but that seems pessimistic.
However, Haldane and others seem to be saying that because there are physical events going on in the brain, which are linked somehow with the mental events, therefore the mental events come under suspicion. I must have a bit of my brain missing here, as I can't see the argument here.
Of course, strong evidence that there is a link is provided by damage to the brain, whether via disease or injury, when thinking, memory, emotions, and so on, can be impaired. I knew someone who couldn't remember who she was, but after medical treatment, recovered. Probably a mini-stroke.
Damn and blast, this is a repetition of stuff on the other thread. Ah well.