From PhilPapers forum Philosophy of Mind:

2009-10-25
Is Functionalism impossible?
It does not surprise me Robin. I am at present involved in a deep discussion with eight other people and we all completely agree with each other person on at least one issue and completely disagree with them on at least one other issue. We have nine viewpoints which all overlap but are also all incompatible. Perhaps next time I meet Andy I will have to ask him how functionalism can be possible.