Question: Whenever I hear someone like, say, Daniel Dennett say that consciousness is an "illusion", I'm always left pretty much stumped. Firstly, both the terms "consciousness" and "illusion" are generally left undefined, although this is more apparent with the term "illusion". With this, I have to use the default definitions of these terms, "consciousness" being a somewhat self-explanatory "state of conscious awareness", and "illusion" being "a delusion of some sort". This is really where the main problem arises for me. How can one claim that consciousness is an illusion when the concept of "illusion" requires a subject to be deluded, which the original claim actively denies the existence of? Granted, this subject doesn't have to be an "I", but the denial of any decieved subject at all seems to negate the argument itself.

The other problem I have with the claim is that it seems to contradict the fairly self evident claim that, as Nietzsche put it, "It thinks, therefore it is".

Is the claim really as nonsensical as it seems, or am I missing something big? Perhaps the definition of a term or multiple terms?

Answer: 
I can't deny myself (the 'I' or the consciousness of being myself). Can you? If you say "Yes", you would never have asked your question. In other words, this question must be asked unconsciously. If you say "Yes" again, why can't you say the consciousness for asking this question is somewhere else? So....

**One can deny everything except consciousness (though actually it is Pure consciousness).**

But there is a chance for denial of consciousness until that person meets a great Guru. In other words, if he says so, that means he has never met such a person. 

In short, I would say, if you try to weld the terms 'consciousness' and 'illusion' the latter burns completely without leaving out a sign of its 'particles'. Our sense organs will become useless after our death, so it cannot show you the 'real knowledge'. The real knowledge must be beyond all the knowledge acquired through our sense organs.

> 
> How can one claim that consciousness is an illusion when the concept
>  of "illusion" requires a subject to be deluded, which the original
>  claim actively denies the existence of?
> 
> 
> 

In enlightenment, when the duality disappears, the observer, the observed and the act of observing all become one. Consciousness is not an illusion.

> 
> Is there any coherent argument in support of consciousness being an
>  illusion?
> 
> 
> 

If there is one such argument, it must never be coherent.

<https://en.wikipedia.org/wiki/Consciousness>

<https://en.wikipedia.org/wiki/Chaitanya_(consciousness)>
When I run across problematic statements of this sort, I always prefer to follow Wittgenstein and look for the error in language that lies behind it. This is precisely the kind of 'philosophy' he thought needed therapy more than analysis.

The first step in that Wittgensteinian therapy is to step back and consider what *purpose* this claim has in Dennett's worldview. I don't mean to ask what the claim *means*, per se. Instead, I want to think of this claim as a move in, say, an abstract, philosophical game of chess, and ask what line of progression this claim is meant to block, or what intellectual territory it is attempting to claim. Looked at that way, the purpose is almost self-evident: the concept of 'consciousness' — ill-defined as it is — has long been associated with metaphysical and religious concepts like God and the soul and moral behavior. Disposing of consciousness immediately undercuts a wide range of philosophical arguments from theology, moral philosophy, and social theory. Since Dennett's *raison d'être* has always been anti-Abrahamic anti-theism, this kind of claim makes perfect practical sense. Whether it makes *philosophical* sense is almost irrelevant, because the position is too useful to the ultimate goal of the intellectual contest to be given up without a fight. This is why he settles on the idea that consciousness is an 'illusion': he cannot deny that we experience something we call consciousness, so instead he tries to pry it away from any direct ontological referent and reconstruct it as an emergent phenomenon of interconnected organic systems. 

Of course, this is just scientism: speculative philosophy based on an over-extension of scientific observations. 'Consciousness is an illusion' is no more empirically verifiable than 'consciousness is the product of a divine soul'. But even as mere scientism it creates enough ambiguity to undercut religious certainty on the matter, so it serves that purpose well.

The therapy in this case is to recognize that neither Dennett nor his opponents have any idea what consciousness *is*, but all acknowledge that the term points at *something*. The rest is merely wrangling over lexical issues: efforts to assert one formulation or another as *a priori* true. We can (if we choose) skip all that as contested territory, and move forward to actual substance of the game, which is over the sociopolitical balance of power between religious and secular segments of modern society.