“Challenges to functionalism through phenomenal consciousness: inverted qualia and absent qualia”

This paper explains the main theses of functionalism about mental states. This view is taken as a response addressed to the metaphysical aspect of the mind-body problem. Thus the paper shows what distinguishes functional properties as second-order properties, and how to understand supervenience and multiple realizability. The author applies these ideas to machine functionalism and analytic functionalism, the two main versions of functionalism.
The model offered by functionalists does not include the qualitative aspect of mental states. This means that non-intentional phenomenological features of conscious experience are not taken into account by this model. It’s a model which does not take into account phenomenal features of mental states; for instance, it does not take into account the quale of being in pain. Pain is not just a functional state in which our mind is placed now or later. It is, besides that, and above all, something that you can feel. If a description of pain ignores its qualitative aspect, and leaves open the door to say that two subjects are in pain, however feeling something opposite (inverted qualia) or not feeling anything (absent qualia), there are prima facie reasons to think that it is a mischaracterization and that the theory that leads to it is seriously flawed.
The difficulty addressed by this paper can be formulated through the following question: is it possible for functionalism to give a satisfactory answer to problems emerging from the possibility of inverted qualia and absent qualia?