Funktionalismi_(mielenfilosofia)
Käänteinen spektri
Tässä ajatuskokeessa kuvitellaan henkilö, kutsuttakoon häntä vaikka Pekaksi, joka on syntynyt sellaisilla ominaisuuksilla varustettuna, että hän näkee värispektrin päinvastoin kuin se havaitaan normaalisti. Päinvastoin kuin muut ihmiset, hän näkee violetin punaisena, oranssin sinisenä, ja niin edelleen. Kuvitellaan, että sinä ja Pekka katsotte samaa appelsiinia. Sinä näet sen oranssina, Pekka puolestaan sinisenä. Kuitenkin kysyttäessä, minkä värinen hedelmä on, sekä sinä että Pekka vastaisitte ”oranssi”. Voidaan havaita, että kaikki käyttäytymisenne ja toiminnalliset suhteenne suhteessa väreihin ovat samanlaiset. Pekka esimerkiksi noudattaisi liikennevaloja samalla tavalla kuin muutkin, vaikka siihen liittyy värien havaitsemista. Käännetyn spektrin argumentin mukaan funktionalismi ei voi selittää kaikkia henkisiä tiloja riittävällä tavalla, koska voi olla kaksi ihmistä, jotka ovat toiminnallisesti samanlaisia, mutta silti heillä on laadullisilta tai fenomenologisilta piirteiltään erilaiset henkiset tilat. <!-- Chalmers (1996) tries to show that even though mental content cannot be fully accounted for in functional terms, there is nevertheless a nomological correlation between mental states and functional states in this world. A silicon-based robot, for example, whose functional profile matched our own, would have to be fully conscious. His argument for this claim takes the form of a reductio ad absurdum. The general idea is that since it would be very unlikely for a conscious human being to experience a change in its qualia which it utterly fails to notice, mental content and functional profile appear to be inextricably bound together, at least in the human case. If the subject's qualia were to change, we would expect the subject to notice, and therefore his functional profile to follow suit. A similar argument is applied to the notion of absent qualia. In this case, Chalmers argues that it would be very unlikely for a subject to experience a fading of his qualia which he fails to notice and respond to. This, coupled with the independent assertion that a conscious being's functional profile just could be maintained, irrespective of its experiential state, leads to the conclusion that the subject of these experiments would remain fully conscious. The problem with this argument, however, as Brian G. Crabb (2005) has observed, is that it begs the central question: How could Chalmers know that functional profile can be preserved, for example while the conscious subject's brain is being supplanted with a silicon substitute, unless he already assumes that the subject's possibly changing qualia would not be a determining factor? And while changing or fading qualia in a conscious subject might force changes in its functional profile, this tells us nothing about the case of a permanently inverted or unconscious robot. A subject with inverted qualia from birth would have nothing to notice or adjust to. Similarly, an unconscious functional simulacrum of ourselves (a zombie) would have no experiential changes to notice or adjust to. Consequently, Crabb argues, Chalmers' 'fading qualia' and 'dancing qualia' arguments fail to establish that cases of permanently inverted or absent qualia are nomologically impossible.