Metaphysics of Mind: Functionalism

Functionalism Chris Ranalli University of Edinburgh  Functionalism: mental-states are functional-roles.  For example, the mental event type being in pain is whatever fulfils the following functional-role: What is functionalism? → caused by bodily damage. → tends to produce the belief that one is hurting. → tends to produce the desire for relief. → tends to produce groans, winces, ouch! .  In short: Being (mental states) as doing (the role they play in the mental system)  topic-neutral (Smart 959) Multiple Realizability  Minds are like computer-programs, brains like computational machines.  Software matters more than hardware.  (Levine 2013). Mental-state commonality and ubiquity trumps physical diversity Examples of functional properties:  Computers  Clocks Multiple Realizability  Being a president  Money To be a computer, or a clock, or a president, or money, something needs to satisfy a certain job description, or perform a certain function, or have a certain role in a system. Is functionalism a form of physicalism?  In principle, functionalism is neutral between physicalism and non-physicalism, as its only logical restriction is that anything which satisfies the relevant functional-roles are candidates for mental-states (see J. Levin 2013, and J. Heil 1998, 89)  As e ll see later, its topi eutrality i ites the o je tio that it s too li eral Blo k -that it allows for economies and governments to have minds. Is functionalism a type of physicalism?  Mi ds are ot disti t i aterial syste s ausally related to bodies. Talk of minds is merely talk of material syste s at a higher le el . Feeli g a pai or thi ki g of Vienna are not brain processes, any more than a computation operation, summing two integers, for instance, is a transistor process. Brain processes and hard are pro esses realize thoughts a d o putatio s (John Heil 1998, 91). Improvement over the (Type) Identity Theory?  Block (1981): the (Type) Identity Theory is species hau i isti .  Why? Because it implies that only creatures with exactly our brain physiology can have our types of mental states.  While functionalism does not strictly entail physicalism, it is easily compatible with physicalism.  Does a functionalist identify mental state types with brain state types? Improvement over the (Type) Identity Theory?  Although mental states and properties are realized by material states and properties, mental states are properties are not identifiable with those material states and properties. Pains, for instance, are […] realized in the nervous system. But the property of being in pain is not a material property (J. Heil 1998, 93). So, being in pain is not a kind of a kind of C-fibre firing. The higher level property of being in pain should not be mistakenly reduced to its realizer (cf. with signalling a left turn and a human arm motion). Higher-level functional property Being pain Functionalist Ontology Lower-level physical property Being a neurophysiological state of type N  Functionalism: mental properties are functional properties: they are identified as properties which fulfil certain causal-roles in the mental system. Functionalist Ontology  Anti-reductionism: mental properties are not identical with, and thereby reducible to , the neurophysiological properties of the brain.  Mental-Physical Supervenience: There is no change in the mental properties (the higher-level functional properties) without there being a change in the physical properties (the lower-level neurophysiological properties0. Mental-Physical Supervenience: Functionalist Ontology [M]ental characteristics are in some sense dependent, or supervenient, on physical characteristics. Such supervenience might be taken to mean that there cannot be two events alike in all physical respects but differing in some mental respect, or that an object cannot alter in some mental respect without altering in some physical respect (Davidson 1970, 88).  There cannot be a mental difference without there being a physical difference.  In general, A supervenes on B if there cannot be a difference in the A-properties without there being a difference in the B-properties. Theory of mind? Three approaches to the nature of mental states:  Machine-state functionalism  Psycho-functionalism Varieties of Functionalism  Analytic-functionalism Ontology of mental-states?  Filler-functionalism  Role-functionalism Machine-state functionalism analyses mental-states into three parts: Machine-state Functionalism  Inputs: the typical cause of the mental state M1  Functional role: the cause and effect relationship between the input and the output  Outputs: the typical responses, such as behaviours B , B , …, and/or mental states M2, M , …., to M1. How should we understand a machine-state? Consider the following table from Block (1978): Machine-state Functionalism For example, a machine-state functionalist might analyse the mental state of being in a pain as follows: Machine-state Functionalism P is a pain = (1) p is the typical cause of tissue or bodily damage (2) p is the typical cause of the belief I’m in pain; the desire for relief; distress. (3) p the typical cause of wincing, tissue protection, groaning, ouch! .  Mental states are analysed not just as the relationship between inputs and outputs, but also the state of the machine. Machine-state Functionalism  For example, the behaviourist would take pain to be the relationship between the input and the output: the cause of pain is tissue irritation or damage (input), and the effect of pain is tissue protection and the expression of the desire for relief (output).  The functionalist adds the internal state of the being, such as wanting to avoid tissue damage, wanting to protect oneself from further damage, wanting to be relieved.  In general, if a creature C is in state S1, and receives input IN1, IN2, …, C will go into state S , S , …., and will cause output O , O , ….. Psychofunctionalism  Psy ho-functionalism […] can be seen as straightforwardly adopting the methodology of cognitive psychology in its characterization of mental states and processes as entities defined by their role in a cognitive psychological theory. […] What is distinctive about psycho-functionalism is its claim that mental states and processes are just those entities, with just those properties, postulated by the best scientific explanation of human behaviour (J. Levin 2013). Psychofunctionalism  Methodological consequences: If cognitive scientists say that there is depression, sadness, social anxiety, then there is. If they deny hysteria, then even if we attribute such states to people [if it is part of our folk psy hology , it s ot s ie tifi ally respe ta le, a d so psycho-functionalism will not posit it as a mental state type.  Psych-functionalism makes all and only the scientifically necessary mental distinctions. Psychofunctionalism  One potential consequence of psycho-functionalism is that even f cognitive science radically diverges from our folk-psychological categories, we will have to regard the posited mental states of psycho-functionalism as real, while denying the reality of our folkpsychological categories. (see Loar 1981, Stich 1983, Greenwood 1991)  But if that s right, it would be hard to see how psychofunctionalism is an account of our mentality. Analyticfunctionalism  The goal of analytic-functionalism is to provide topicneutral analyses of our ordinary, folk psychological mental-state concepts.  e.g. Belief, desire, hope, sadness, happiness, longing, remembering, etc.  How should we understand a mental-state like being in pain? We define the mental-states using a Ramsey sentence (Lewiis 1972): Functionalist definitions of mental-states Ramsey sentence for pain: ∃x∃y∃z∃w(x tends to be caused by bodily damage & x tends to produce states y, z, and w, & x tends to produ e ou h! .  Whatever satisfies the Ramsey sentence for pain has the mental state type pain. Rolefunctionalism and Realizerfunctionalism Even if mental states are functional states, that still leaves open how we should understand the ontology of theses states.  A role-functionalist will say that pain is the higher-order property, the pain role (the corresponding Ramsey-sentence for pain).  A realizer-functionalist will say that pain is the lower-level property, the pain-role-realizer, which satisfies the pain-role (whatever stuff satisfies or makes true the corresponding Ramseysentence for pain).  Block s Liberalism/Chauvinism Dilemma Ned Block on Functionalism  Functionalism is too liberal: the Chinese nation example, the homunculi example, the economy example.  Functionalism is too chauvinistic: the Martian example.  Block s argument from absent qualia against functionalism  If functionalism is true, then if China runs the tooth-ache program, China is in pain.  If common-sense functionalism is true, then economies and governments have mental states. Block s Dilemma  Too liberal! Governments/Economies plausibly cannot have mental states.  If psycho-functionalism is true, then certain possible creatures (e.g. beings that are fulfil the common-sense functional roles, but have different neurological-psychological functional roles) would not have our mental states.  Too chauvinistic! These creatures plausibly can have our types of mental states. The first horn: Functionalism is too liberal. Block s Dilemma  The China-brain example: “uppose we convert the government of China to functionalism, and we convince its officials that it would enormously enhance their international prestige to realize a human mind for an hour. We provide each of the billion people in China (I chose China because it has a billion inhabitants.) with a specially designed two-way radio that connects them in the appropriate way to other persons and to the artificial body mentioned in the previous example. We replace the little men with a radio transmitter and receiver connected to the input and output neurons. Instead of a bulletin board, we arrange to have letters displayed on a series of satellites placed so that they can be seen from anywhere in China. Surely such a system is not physically impossible. It could be functionally equivalent to you for a short time, say an hour  The second horn: Functionalism is too chauvinistic. Block s Dilemma  Block s Martian example: We develop extensive cultural and commercial intercourse with them. We study each other s science and philosophy journals, go to each other's movies, read each other's novels, etc. Then Martian and Earthian psychologists compare notes, only to find that in underlying psychology, Martians and Earthians are very different […]. Now imagine that what Martian and Earthian psychologists find when they compare notes is that Martians and Earthians differ as if they were the end products of maximally different design choices (compatible with rough Functional equivalence in adults). Should we reject our assumption that Martians can enjoy our films, believe their own apparent scientific results, etc.? Should they reje t their assu ptio that we e joy their novels, lear from their textbooks, etc.? […] [S]urely there are many ways of filling in the description of the MartianEarthian difference I sketched on which it would be perfectly clear that even if Martians behave differently from us on subtle psychological experiments, they nonetheless think desire enjoy, etc. To suppose otherwise would be crude human hau i is  In short: like behaviourism, functionalism is too liberal, because it ascribes mentality to entities which plausibly lack mentality. But, like the type-identity theory, functionalism is too chauvinistic, because it denies mentality to entities which plausible have mentality. Block s Dilemma  Thinking about how we ought to functionally characterize the inputs-outputs and their relations to other mental states pushes us to oscillate between an approach which is too liberal (e.g. commonsense functionalism) and an approach which is too chauvinistic (e.g. psycho-functionalism), so that functionalism, however characterized, gives us the wrong predictions (e.g. some entities which do t have minds are attributed with minds, and some entities which have minds are attributed as not having minds). The Absent Qualia Argument: (1) If Functionalism is true, then if China runs the tooth-ache program, China is in pain. (2) Functionalism is true [assume for reductio] Therefore, from modus ponens on (1) and (2): Absent Qualia Argument (3) If China runs the tooth-ache program, China is in pain. But: 4 It s ot the ase that: if Chi a ru s the tooth-ache program, then China is in pain.  Between (3) and (4). Therefore: (C) Functionalism is not true. 1. Blo k s argu e t that fu tio alis is too hau i isti targets realizer-functionalism. If role-functionalism is not chauvinistic, is it too liberal? Critical Questions 2. Realizer-functionalism seems to be in a better position to account for the causation between mental-states and bodily-states. Can role-functionalist explain psycho-body causation as easily (or at all)? If so, how? 3. Blocks Absent qualia argument seems to present an obstacle for functionalism. Does it also lend support to dualism, because it implies that there can be phenomenal-properties (mental-properties typed by what it is like to have them), even though the corresponding functional roles are satisfied?