We can work at it instead with progressive narrowing, either in the positive or negative case. We can all agree some random rock is not conscious, that excludes a lot of the possibility space. Are trees? No? That excludes even more and prevents an easy "has DNA" filter. I do have an easy filter though: I would tentatively accept a simple statement of "I am conscious" as strong demonstration of consciousness, and failure to do so a strong indicator of lacking consciousness. This rules out most animals, which, fine, and also rules out brain damaged humans who don't seem to comprehend speech let alone produce it, again, fine.
There's the interesting edge case of when a computer program says the same, is it conscious? No in general, I argue, because for most programs a programmer could go in and easily have it say whatever the programmer wants. Ok, it's a more sophisticated program like GPT3, and suppose it said that? GPT3 is rather complex, you can't easily go in and edit its output to be whatever for an input. So is it conscious? No again, but admittedly this can be considered breaking my filter and so I'd have to use a different criteria to rule it out. (The related negative "Thinking is what computers can't do yet" works well and it narrows year by year.) Still, it's a useful filter in most cases! Besides, I don't want to rule out consciousness from silicon anyway since even if somehow AIs can never have it, human ems surely would. At that far point, the filter can still be useful, for instance it would accept the character Data as conscious simply because he declared himself to be so and there's no easy way to make him as-a-program declare otherwise.
I'm reminded of Plato's man, the featherless biped, and how it had to be refined to a featherless biped with broad flat nails when Diogenes produced an edge-case that broke the definition. While perhaps the definition should have been more fundamentally refined rather than just extended, as it's still missing so much of what makes a man, it's still a useful act of incremental change to better get at what is meant, and allows one to proceed in doing whatever it was of importance until the obstacle presented itself.
Once we understand that our words are not typically perfect pointers to a crisp concept in thing-space, we can work on refining our words and avoid misuses of words that blur things further. This refinement can be worked at positively by creating crisper borders around the thing, but it can also be worked at negatively by partitioning off sections of the space where the concept clearly does not belong. This latter approach seems to be looked down on more and thus less-used, but it's still useful and valid in trying to communicate ideas.
Posted on 2021-12-19 by Jach