The modal argument, in essence, says that sometimes, when you can imagine X without Y, it is because you have erroneously allowed the term “X” to refer to something else. But since the term “pain” cannot refer to anything other than that which is painful, that cannot be happening when you imagine pain without c-fibers firing. The rest of the argument goes: ATherefore, when you imagine pain without c-fibers firing, that must be because it is genuinely possible. But if it is possible for pain to exist without c-fibers firing, then they must not be the same one thing.BTherefore, when you imagine pain without c-fibers firing, what you are imagining is in fact impossible, because pain and c-fibers firing are the same one thing. CTherefore, when you imagine pain without c-fibers firing, that must be because it is genuinely possible. But if it is possible for pain to exist without c-fibers firing, then they must be the same one thing.DTherefore, when you imagine pain without c-fibers firing, that must be because you are imagining “pain” coming to refer to something else, other than pain. This is the mistake in the modal argument.