“What is Functionalism?” originally printed in Readings in Philosophy of Psychology vol.1, 171-184 (MA: Harvard University Press, 1980).
“What is Functionalism” is first and foremost an encyclopedic article; as such it is mostly descriptive rather than argumentative. Nonetheless, in its exploration of the theory of functionalism in the philosophy of mind, it does present an argument against the idea that functionalism supports physicalism – the view that all things and all properties are physical.
Block begins by delimiting several senses of ‘functionalism’ used by philosophers. The first is functional analysis, whereby a system is decomposed into functionally isolated parts and the function of the system explained in terms of these parts. Then there is computation-representation functionalism, which is an explanatory strategy in cognitive science whereby mental states are analyzed as computations taking place over representations. Finally, there is metaphysical functionalism, which examines what mental states are, and in virtue of what are states such as pain similar to one another. The article is concerned solely with this latter sense of functionalism.
Block states that metaphysical functionalism identifies mental states with functional states. A functional state is just a specific causal role in a larger system (in this case, a mind) and is intricately linked with stimuli, other mental states, and behavior. As such the functionalist answers the question “In virtue of what are X’s, X’s rather than Y’s?” (where X and Y are types of mental state, e.g., pain) by saying that X’s are all X’s in virtue of their functional role in the systems of which they are a part, regardless of their physical realization.
Then Block proceeds to describe the first version of functionalism, machine functionalism. Presented by Hilary Putnam in the early 1960’s, machine functionalism argues that mental states are not just functional states, but more specifically are machine table states of a hypothetical machine called a Turing Machine. Turing Machines are automatons which can, in principle, compute any problem and which do so in virtue of what are called ‘system states,’ which are tied to instructions for computational steps (e.g., “If in system state S, perform computation C and then transition into system state S2, and so on). (Readers are encouraged to look at my summary of Putnam’s article if they want more detail on his presentation of machine functionalism.)
Block points out that machine functionalism is not the most general formulation of functionalism available; as such, he presents a more general version, using the tools of formal logic (persons not familiar with these tools might want to skip this part of the summary unless they are overly curious):
1. The first step is to reformulate a theory T (either ‘folk’ or ‘scientific’) of psychology such that is is a long conjunctive sentence with all mental state terms as singular (i.e., in the form of ‘has pain’ rather than ‘is in pain’):
T (s1 . . .sn)
‘s1 . . . sn’ are sentences including mental state terms.
2. Then, variables should be placed in the spot of mental state terms, and existential quantifiers for these terms prefixed. This forms what is called the ‘Ramsey sentence’ of the theory (named after Frank Ramsey, the genius who formulated this methodology):
∃x1 . . . xn T(x1 . . . xn)
‘∃x1 . . . xn‘ is the set of existential quantifiers prefixed to the theory, and there should be as many of them as there are mental state terms in the theory. ‘(x1 . . . xn)’ is the set of variables which now sit in the theory where the mental state terms used to.
3. Thus, if ‘x1‘ is the variable that replaced ‘pain’ in the psychological theory, we can now define pain as follows:
Y is in pain iff: ∃x1 . . . xn [T(x1 . . . xn) & Y has x1].
Since the sentence formerly expressing the mental state term ‘pain’ described it in terms of its relations to stimuli, other mental states, and behavior, pain is found to be whatever fulfills the relations which x1 exhibits.
Pain can be expressed as the property ascribed when one says ‘X has pain.’ Then, pain can be identified with the property expressed by the predicate ‘∃x1 . . . xn [T(x1 . . . xn) & Y has x1]’. Block gives us an example: if our psychological theory defines pain as being caused by pin pricks, causing worry & loud noise emission, and if worry subsequently caused brow wrinkling, then pain can be identified with the property expressed by the predicate ‘∃x1∃x2[(x1 is caused by pin pricks and causes loud noise emission and x2 & x2 causes brow wrinkling) & Y has x1]’.
This is the essence of the Ramsey method for defining mental state terms causally. Block supplements this method with extra notation for convenience’ sake. He establishes that ‘%xFx’ should be understood as ‘being an x such that x is F.’ Once this notation is introduced, we can define pain as follows: pain = %y∃x1∃x2[(x1 is caused by pin pricks and causes loud noise emission and x2 & x2 causes brow wrinkling) & Y has x1]. This just means that pain equals being a y (a thing) and being in x1, where x1 is caused by pin pricks . . . etc.
Block clarifies functionalism’s relation to behaviorism and traces the historical origins of functionalism as well. Behaviorism is the doctrine that mental states are to be analyzed purely in terms of behavior and behavioral dispositions. So, desiring an ice cream cone is just the disposition to grab a cone when one is present; and nothing more. Functionalism is importantly related to behaviorism because it also analyzes mental terms using behavioral responses to stimuli. The differences is that functionalism also refers to other mental states; further, these other mental states are interlinked with each other, stimuli, and behavior in a web of causal relations.
Block traces the development of functionalism to two developments in the philosophy of mind. The first is the ‘multiple realizability’ argument, originating with Hilary Putnam in his presentation of machine functionalism and subsequently used by Jerry Fodor in developing a method of explanation in psychology. The multiple realizability argument states that a mental state is unlikely to be a physical structure (such as a brain state) because it is eminently plausible that different physical structures – non-brain structures, for example – can realize mental states. So, pain is unlikely to just be C-fiber stimulation (or some other appropriate brain state), because octopuses and other such creatures can probably feel pain, despite their not having C-fiber stimulatory capacity. This led to the development of functionalism, which promised to unify physically different phenomena under the banner of causal (functional) similarity.
The second historical development leading to functionalism’s rise was JJC Smart’s development of ‘topic-neutral’ analyses of mental states. Smart was arguing for the identity theory of mind (see my summary of his article), the view that mental states equal brain states in the strict sense of identity. He needed, however, to respond to the objection that even if mental states were brain states, certain properties of these states were irreducibly mental, such as ‘sharpness.’ Smart responded by analyzing such property concepts in topic-neutral terms, or terms which did not indicate whether the property was physical or not. Other philosophers expanded upon these analyses, turning them into functional definitions of mental state terms (see, e.g., my summary of David Lewis’s philosophy of mind articles).
The introduction to this summary stated that Block argues against the idea that functionalism at all implies physicalism. The argument is strewn about the text and takes the form of two mini-arguments: one against the idea that functionalism supports type physicalism, and the other against the idea that functionalism supports token physicalism. Type physicalism is the view that, e.g., pain is a type of physical thing. Token physicalism, meanwhile, is a weaker thesis, holding merely that each individual instance of pain is a physical thing. The former implies the latter, but not vice versa.
Block delineates those who think that functionalism implies that physicalism is false from those who think it is true with labels: functional state identity theorists think physicalism is false because mental states are equivalent to functional states, which are non-physical. Functional specification theorists, meanwhile, think that physicalism is true because functional definitions (where pain = occupant of Causal role R, in the manner specified by the Ramsey method) lead us to physical mechanisms which fulfill the causal role in an organism. This leads to the view that pain-in-humans is C-fiber stimulation, since it occupies causal role R, and so on for all species.
Blocks argues against the idea that functionalism supports type physicalism by pointing out that, even if functional reductions are correct in the sense that a physical mechanism will be found to occupy causal role R, there is some non-physical facet of the various physical mechanisms which makes them pains rather than, say, pleasures. So type physicalism is false because mental state types are irreducibly functional. Meanwhile, even the weaker thesis of token physicalism is not supported by functionalism, in Block’s eyes. This is because there are conceivable entities which have non-physical states (such as soul states) which function just as mental states do. With functionalism negating type physicalism and not at all implying token physicalism, it seems as if functionalism does not support physicalism at all.
Functionalism does not support physicalism
Functionalism negates type physicalism.
S1. If type physicalism is true, then mental state types are physical, e.g. pain is a brain state.
S2. If functionalism is true, then mental state types are functional, i.e., non-physical states.
S3. A mental state type cannot be both physical and non-physical.*
S4. Therefore, functionalism negates type physicalism. [S1-S3]
2. Functionalism does not imply token physicalism.
S1. In order for functionalism to imply token physicalism, all conceivable tokens of mental states types would need to be physical.
S2. Yet, non-physical mental state token are conceivable, e.g., soul states rather than brain states.
S3. Therefore, functionalism does not imply token physicalism. [S1,S2]
3. Therefore, functionalism does not support physicalism. [1,2]