In evaluating the validity of Functionalism as a theory of mind, one must first understand the philosophy of Functionalism itself, and its roots. Functionalism has divided philosophers, and presented below are three of the main arguments against the validity of Functionalism, and these will demonstrate that as a theory of mind, although compelling and thought provoking, Functionalism is ultimately not viable.
Functionalist theory has evolved from other philosophical theories of the mind, including Identity Theory of Mind, which in its simplest form states that mental states can be said to be exactly identical to brain states, and some forms of Behaviourist Theory, which suggested, amongst other things, that behaviour can be explained or justified without putting any emphasis on the mind as an instigator, and so behaviour can be rationalised by saying that the sources are not internal, but external.
Functionalism can be said to be both and extension and a criticism to these theories. It is something of a middle ground between them. Similar to Behaviourist theory, Functionalism classifies mental states using a behavioural structure, but differs from this theory by suggesting that mental states originate internally. In terms of similarity to the Identity Theory of Mind, both agree that the process of producing a mental begins internally, but Functionalism differs in that it differentiates between the definitions of ‘mental states’ and ‘brain states.
In its basic form, Functionalism can be defined as suggesting that mental states are characterised by their causal properties. In other words, instead of defining a mental state by its features, Functionalism suggests that it should be defined by what it does, or by its function. Expanding on this, Functionalism suggests that two thoughts can be considered identical if all relevant inputs, both those garnered internally and externally, can achieve the same eventual output.
One of the first forms of Functionalism was created by Hilary Putnam, who, using the Turing Test, demonstrated his theory of Machine State Functionalism. The Turing Test was a proposal by Alan Turing to discover whether machines can imitate human behaviour in a manner satisfactorily enough that they appear to be able to think, and furthermore, Turing suggested that his test might, with more technological advancement, be able to determine if a machine is in fact able to think. Using the Turing Test, Putnam suggesting that any being possessing a mind could be said to be a Turing machine, and could be controlled using a set of instructions for its operation. Furthermore, early Functionalist theories suggested that a person or machine could be controlled by the input of instructions based on the probability of an outcome, and thus the behaviour would be modified according to the most likely outcome. From this, Putnam created his idea of Functionalism which suggested that sentient beings differ from non sentient beings not because of their physical make up, but because of the way that the internal mental states relate to one another causally to form outputs.
However, Putnam later rejected his earlier proposals for Functionalism, citing his Twin Earth thought experiment as justification, and, being that he was instrumental in the formation of Functionalist theory, this gives weight to the argument that Functionalism as a philosophy of mind is not viable. The Twin Earth experiment is based around the idea of two identical worlds, except for one thing, that water is has a different name on the ‘twinned’ earth. As Yemina Ben-Menahem writes in Hilary Putnam, the two people involved, Oscar and Toscar refer to the liquid water as what is ‘familiar to them in their respective environments. Yet the liquids…are in fact very different.’ (p.236, ll.23-24). What this thought experiment is suggesting therefore, is that Oscar and Toscar’s thoughts about water are based on their knowledge of it. By extension, this suggests that for a person to have thoughts about water, they must have experienced it, since the brain itself has no such knowledge of water. Thus, some form of external stimulus must have created the knowledge of water in order for the brain to process it. This refutes the idea in Functionalism that mental states are created internally.
A criticism of Functionalism, and indeed of all materialist theories, is that it does not account for the complexities of human emotion and feeling. For example, what is missing in the theory of Functionalism is the allowance for subjective, conscious emotion, or qualia. The argument for the existence of qualia is rooted in the idea that some emotions, namely pleasure and pain, cannot be analysed in an objective manner. If the example of pain is taken from a Functionalist standpoint, its only property is that it creates the appropriate output, such as flinching. However, it is difficult to imagine that this is the only component of pain. From the point of view of a Functionalist, pain is not defined in terms of how it makes a person feel, or what it is made of, but rather only in terms of what is input to create the relevant mental state, and what the output of that is.
The problem with using qualia as an argument against the validity of Functionalism as theory of mind is that not all philosophers believe that qualia exists. However, if one agrees to the possibility of the existence of qualia, then this argument is valuable. As Edmund Leo Wright argues in The Case for Qualia, human experience can ‘support the existence of qualia…qualia realism should be our default position.’ (p.286, ll.11-13). Using this standpoint as a basis, two arguments can be levelled against Functionalism and its validity. The first argument builds on Putnam’s own objection to his theory of Functionalism, and the relationship between cognitive function and experience. The example of colours can be used to illustrate this point. If a person sees red and calls it red, and another person sees it as green but calls it red, the function is identical, but the personal experience is not. Jaegwon Kim demonstrates this in his book, Physicalism or Something Near Enough, where he writes that what a colour looks like to a person ‘should make no difference to the primary cognitive function of [their] visual system,’ (p173, ll. 2-4). In other words, Kim is arguing that the Functionalist approach does not allow for the variety of subjective experience. He goes on to qualify this: ‘Intrinsic qualities of qualia are not functionalisable and therefore are irreducible, and hence causally impotent.’ (p.173, ll.9-10) If the existence of qualia cannot be reconciled with the theory of Functionalism, as Kim suggests, then the two must be mutually exclusive. If one assumes that qualia exists, as suggested by Wright, then Functionalism is not a viable theory of mind. Clearly, for this argument to be valid, one must first accept the existence of qualia. As such the argument from a qualia standpoint is not sufficient by itself to invalidate Functionalism if the existence of qualia is not proven. Indeed, the theory of Functionalism can be used as an argument against the existence of qualia, and no explanation for either theory has been issued which does not rely upon unknown factors and speculation.
Arguing the case for Functionalism’s shortfalls in terms of consciousness, Ned Block proposed a thought experiment in which a functioning mind could be created out of an entire Chinese nation. The point of this thought experiment was to illustrate that the theory of Functionalism fails to directly address the issue of consciousness as a condition of a mental state or functioning mind. As explained by Eric S. Chelstrom in Social Phenomenology: Husserl, Intersubjectivity and Collective Intentionality, ‘If consciousness could be defined in only strictly functional terms, it would be possible for the population of China as a whole to realise the functionality of consciousness.’ (p.55, ll.17-19). If one were to take the Functionalist view on this matter, then this thought experiment should seem entirely plausible, since in keeping with Functionalist views, it does not matter what the mind is made up of, it matters only that functional roles are realised by different parts, as would occur in the Chinese nation scenario. There should be no need, Functionalism would argue, for the mind to be made up of anything specific. Indeed, providing the roles were carried out, it could be made of anything imaginable. As Ned Block points out, the idea of the Chinese nation as a whole having a collective consciousness, and by extension, the suggestion that a conscious mind could be made up of number of functioning parts of any description, although not necessarily impossible, seems absurd to most people, and as such demonstrates a flaw in the argument for Functionalism as a viable theory of mind.
As established previously, there are a number of arguments against Functionalism as a viable theory of mind, and these must be taken into account when weighing up whether one agrees or disagrees with them. However, the basis of the theory of Functionalism, that mental states are only defined by their function, is one that is not easily reconcilable with the wealth of human experience. In fact, the idea that human experience is secondary to functioning mental states is somewhat abhorrent, since it is in human nature to want to believe that consciousness is a meaningful phenomenon and not an illusion created by causal functions. Furthermore, in accepting Functionalism in its entirety, one must also accept that that the machine function model suggested by Putnam could also be viable, and furthermore, that conscious beings are not unique and extraordinary, but can be created with any components, provide the equation of input and output is valid. This is a somewhat undesirable situation, and seems ridiculous as it is based in speculation of unknown factors. Ultimately, it can be said that Functionalism is not a viable theory of mind since it requires a suspension of one’s experience of behaviour the knowledge of one’s own consciousness, and is based almost completely on conjecture.
Matravers, D (2011) Mind (A222 Book 5), Milton Keynes, The Open University
Ben-Menahem, Y (2005) Hilary Putnam, Cambridge, Cambridge University Press
Wright, E (2008) The Case for Qualia, Massachusetts, MIT Press
Chelstrom, E (2012) Social Phenomenology: Husserl, Intersubjectivity and Collective Intentionality, Maryland, Lexington Books