What evidence or valid arguments can you give that my cell phone is not plotting against me and that my cell phone does not yell at me when no one else is listening? Since it only yells at me when no one else is listening, you have no access to evidence about that. And since whatever happens can be interpreted as an element of my cell phone’s plot against me, I can’t see how the claim is inconsistent with the observable. You can present a good inductive argument, I suppose, such as “cell phones don’t have minds, so they can’t plot.” But then I reply “most cell phones don’t, but mine does. I even have evidence for this: It yells at me. Nothing without a mind can yell at people.”
Or do you mean to say that, when C is delusional, A and B can provide each other evidence and valid arguments that C’s cell phone is not plotting against C and that C’s cell phone does not yell at C when no one else is listening, even though there may be no evidence or valid arguments A and B can present C?
Notice that the “imaginary world” person believes something for which you and I have very clear evidence that it is false. Namely, the “imaginary world” person thinks the table is not really there, that it’s all in his head, whereas you and I have direct evidence that there is a table there, and a very good inductive argument for that claim. The evidence is our seeing the table. The argument is that the existence of the table follows inductively from the fact that generally, when we feel awake and aware, and we think we see a table, there is in fact a table there. The evidence and argument are there, but the “imaginary world” believer does not accept them. But this is no different than the cell phone case.
The cell phone belief sounds to me to be just as unfalsifiable (for the one believing it), just as unamenable to evidence and argument, as the imaginary world belief, so I’m still not seeing your distinction.
I think you might be trying to make a distinction between a straightforward hallucination on the one hand, and a theory about the cause or nature of one’s experience on the other. I think you think a delusion is more like a hallucination, and that you think the belief “everything is a figment of my imagination” is not a hallucination but a belief about the cause or nature or meaning of one’s experience. I think there’s a good distinction to be made there, but I don’t think I would mark the distinction using the word “delusion.” I think both kinds can constitute delusion. The “imaginary world” believer doesn’t think there’s a table here, but there really is a table here. That sounds delusional to me. In fact, when I put it that way, the distinction between hallucination and theory of the world in this case becomes blurry for me. The claim “there’s no table here, it’s all in my head” sounds pretty close to hallucinatory in this situation.
-FrL-