I'm trying to get my head around the idea that if you don't believe in these virtual worlds, then you're a dualist.
In RD's case, it seems to be related to a philosophical notion that, because we can access the subatomic world only by gleaning information about interactions of stuff that we can't access directly, then it must be non-stuff with no qualities, and the interactions must be all that's real. (All syntax, no semantics.)
From there, it is apparently deduced that information about interactions (syntax) alone is enough to produce a "real world"... because, hey, it produces our world!
Then there's a tremendous leap out of the subatomic realm to the macro world, and this unsupported philosophy is applied here, too, so that preserving information about a system's interactions is enough to replicate that system.
This would mean that if I preserve enough information about my house in a blueprint, so that it would allow the house to be perfectly rebuilt, then I have actually created a new house by virtue of creating the blueprint, and I don't have to bother to actually build it.
When it's put like that, of course it's exposed as a ridiculous notion.
But bring computers into the mix, and it's supposed to be different, because computers are programmable -- in other words, you can decide the syntax, which means if you reproduce the house symbolically via computer (rather than a blueprint) you have actually created a new system that we can speak of as having an independent existence somewhere other than the physical world in which the computer exists and somewhere other than in our imaginations, because you've preserved the syntax.
The problem here is that the introduction of the computer, rather than paper, doesn't change the fact that there simply is no other frame of reference available besides the physical universe and our imaginations.
Nor does it change the fact that the qualities of the media used for symbolic reproductions remain what they are, regardless of the qualities of the system being symbolized.
Nor does it change the fact that the symbols -- whether on a blueprint or a computer monitor -- can only be associated with the system being represented if they are observed and interpreted, and that this takes place in the observer's imagination, not in any other "world".
So if I want to create a new house, I can't recreate the old one symbolically. I have to do it non-symbolically, with actual building materials. (And this is true regardless of anyone's philosophy about the quantum foam.)
And if I want a machine that paints cars, it can have a computer in it, but I can't
program a computer to paint cars... I have to
build a machine that paints cars.
So back to consciousness....
Nature builds all the organs of our bodies out of real stuff. And all the bodily functions are carried out by real stuff in real spacetime. Consciousness should be no exception.
So if you want a conscious machine, you'll have to build it. There is no reason to believe that we can dispense with the building and simply program an otherwise non-conscious machine to be conscious.