Illusionism undermines Epistemology It seems to me that the meaning of 'illusion' in this context is not so much 'it doesn't exist' as, 'it's not what it seems', in much the same way as the phantom limb pain an amputee may experience is illusory - it's a real pain experience, but is not what it seems to be (a pain in a limb). Similarly, the illusion of consciousness is that it is not what it seems; i.e. it feels like a consistent, unitary, continuous, agent self, when it really isn't.
In the case of colour, sometimes called a '
secondary quality', the 'illusion' is that objects don't themselves have colour, they reflect various wavelengths of electromagnetic radiation that we use to construct the experience of colour, but the wavelengths are only a guideline - we apply various transforms, such as
colour constancy, to make our experience coherent.
I can only make sense of Dennett's denial of consciousness in these terms; I have similar difficulty with his compatibilist defence of moral responsibility....