Man, If I had a nickel every time someone used that reply...
> If there is no subject, there can't be an illusion.
A common misconception, but incorrect. An illusion is simply a fact that, when taken at face value, entails a false conclusion. There is no reason a computer system can't be deceived by an illusion too, even one without "consciousness".
> An illusion is simply what fact? What does it mean to take it at "face value"? What "false conclusion" does it entail?
A fact is an observation, a sensory input, a measurement, etc. The observation of a pencil in water [1], if taken at face value, entails a false conclusion.
If instead such a fact were integrated into a larger set of facts from which we infer a coherent picture of reality, a very different conclusion emerges.
No part of the above depends upon any sort of subject.
> I think you're equivocating here. What definition of illusion are you using?
I'm not. I'm using the same definition that I provided to you, namely that an illusion is a fact that naively entails a false conclusion. If you want a dictionary.com definition, "something that deceives by producing a false or misleading impression of reality".
Of course, you could jump on "deceives" again with some unnecessary appeal to subjectivity, which is why I say "entails a false conclusion" instead.
> If there is no subject, there can't be an illusion.
A common misconception, but incorrect. An illusion is simply a fact that, when taken at face value, entails a false conclusion. There is no reason a computer system can't be deceived by an illusion too, even one without "consciousness".