[redial]

> I'd also put consciousness up there, because it's fundamentally distinct from measurable things.

No one knows that it is not measurable. Is love measurable? is hunger? happiness? they seem to be as measurable as consciousness, that is to say we can at least measure them in binary as either present or not.

[andrepd]

How do you know everyone else is not a "p-zombie", indistinguishable in any external way from a human such as yourself, but devoid of internal "consciousness"/"subjective experience". Even the mere logical possibility of p-zombies indicates that consciousness is unmeasurable.

[redial]

Solipsism is basically the only defense against the conclusions from the evidence of the "real" world. But if you argue for solipsism then I say you have much bigger problems than consciousness because you basically rejected everything that has ever been "known" or experienced. If you reject our "shared reality" then anything is possible, including paradoxically, the "shared reality".

If you accept the shared reality on the other hand, consciousness is measurable to some degree. So the real question is do you or do you not accept we share experiences?

As an addendum, if it is all up to me as you suggested, I just made consciousness measurable so there is no need to keep arguing about it.

[pmoriarty]

"Solipsism is basically the only defense against the conclusions from the evidence of the "real" world."

Far from it. There could very well be an external world, and one populated by plenty of other and fully real human beings even, but your own personal view or understanding of it could be distorted or false.

This could be simply because you're hallucinating, or insane, or your brain could be injured, or could be living in a virtual reality (which itself exists in some other "real" reality), or you could be the proverbial brain in a vat, or aliens (or god or a demon/devil) could be deceiving you, etc.

[redial]

All those options are the same: they are either part of a shared experience or they are not. Nothing is preventing a demon from deceiving me right now, in fact one can come anytime I'd love to meet him, preferably her.

[pmoriarty]

If experiencing something that's not shared is the only qualification for solipsism, then we're all solipsists, as (arguably barring the possibility of telepathy) our experiences are all private.

But that's not what solipsism typically means. Solipsism usually refers to the position that only you (or perhaps only your own mind) exist. By that commonly accepted definition, one could be mistaken or deceived in any of the ways I laid out earlier without them entailing solipsism.

[redial]

I meant to say shared context. Everything you said is part of a shared context or not, those are the only two options.