A quick list of some of the relevant issues and arguments we have considered. Most have been discussed in class; others are in the readings but have not been discussed much in class. This is just meant to be a starting point for your study. I don't pretend that this handout lists all the important arguments, and for those it does list, it certainly doesn't contain a full enough description to enable you to do well on the midterm!
I. Positions on the Ontology of the Mind
The first several topics we examined were various responses to the mind-body problem, i.e. various views about the ontological nature of mental states.
Substance dualism is the view that there are two radically different kinds of substances: mental substances, which have no physical properties at all (e.g. no mass, no location in space, etc.), and physical substances, which have no mental properties at all (no thoughts, no conscious experience, etc.). Ryle does a nice job of elaborating this view prior to his critique of it.
interactionist dualism, epiphenomenalism, parallelism, occasionalism
Kim surveys many arguments for dualism in chapter 2. He distinguishes between two main kinds of arguments: epistemological and metaphysical. Both kinds of arguments note a property that mental events or properties have but physical events or properties apparently do not have, and use this difference to argue that mental events cannot be physical events.
One epistemological argument is the following (similar to Kim's Argument 1, p. 34):
Argument from indubitable existence (related to Descartes in Meditations 2 and 6):
1. My thoughts have the property of indubitable existence.
2. No physical process has the property of indubitable existence.
3. If x and y have different properties, then x is not identical with y
Therefore,
4. My thoughts are not identical with any physical processOne metaphysical argument is the following (similar to Kim's Argument 7, p. 39):
Argument from the necessity of identity:
1. If x = y, then x = y in every possible world (NI, the necessity of identities)
2. There is a possible world in which I have a different body than the one I actually have
3. Therefore, I'm not identical with my body (this one) in every possible world (from 2)
4. Therefore, I'm not identical with my body, period (from 1 and 3)
The main argument against dualism is that it seems incompatible with mental causation. Kim presents two versions of this argument:
Argument from mental causation, version 1:
1. Minds have causal effects on bodies.
2. The physical universe is a closed system: every physical event has a physical explanation.
3. If nonphysical minds could cause physical bodies to do something, then there would be physical events with no physical explanation.
Therefore,
4. Nonphysical minds cannot cause physical bodies to do anything. (from 2 and 3)
Therefore,
5. Dualism is false. (from 1, 4, and the definition of dualism)Argument from mental causation, version 2 -- the "pairing problem":
1. My mind causes my body to do things, but it doesn't cause other similar bodies to do things.
2. The only feasible explanation for (1) is that my mind is in physical proximity to my body but not to other bodies.
3. But according to the dualist, minds do not have physical locations.
4. Therefore, dualism is false. (From 1-3, since if dualism were true, there would be no explanation for (1).)
I. B. Behaviorism
In class, I distinguished between a linguistic thesis, a methodological thesis, and a metaphysical thesis. The most basic of these is the metaphysical thesis. This says that to be in a mental state of a certain type (e.g. pain) is to behave in certain ways (e.g. wincing, moaning, etc.), or, in more sophisticated versions, to have a disposition to behave in certain ways.
(The linguistic thesis says that terms for mental states mean the same as, or can be defined in terms of, terms for behaviors or dispositions to behave. The methodological thesis says that psychology should not depend on hypotheses about "internal" mental states. See this handout for more.)
1. Linguistic argument: consider how we learn words for mental states like pain. We learn to apply them by associating them with publicly observable behaviors. So the criterion for applying such a term involves behavior. So the meaning of the term is given by a set of behaviors. But if 'pain' means a set of behaviors, then pain = a set of behaviors. (one line of response: distinguish verification conditions from truth conditions.)
2. Epistemological argument: we must be able to conclusively verify any scientific hypothesis; we can't conclusively verify hypotheses about inner states; so scientific psychology can't refer to inner states.
1. Evidence that any psychological theory complex enough to predict human behavior will need to invoke internal states. (Compare the problem of predicting a computer's output on the basis of its input: hopeless without an account of what's going on in between. Surely humans are at least this complex.)
2. possibility of mental state without associated behavior (consider Dennett's example of curare + amnestic).
3. possibility of behavior normally accompanying a mental state without the presence of the state (acting; this is the converse of 2).
4. The dispositional version of behaviorism seems to either be circular or involve an infinite regress. Believing that today is Monday is the state such that if I am in it, and I want to tell the truth when it won't harm me, and I believe that it won't harm me to tell the truth about what day I think it is, and . . . then if someone asks me "Is today Monday?" I will say "yes." But this definition appeals to desires and beliefs which will also need to be behavioristically defined, and their definitions will appeal to still further beliefs and desires. It seems unlikely that there's any way to give these definitions without circularity or regress.
Reading: Kim, chapter 4. My handout: http://www.trinity.edu/cbrown/mind/kimChapter04.html.
The view that mental states (or at least some of them, notably qualia, "raw feels," conscious experiences) are identical with neurophysiological states.
1. Argument from simplicity. Suppose we have two rival theories about the relation between mind and body. One is the identity theory, the view that mental states simply are neural states. The other is a dualist theory. The dualist theory involves more kinds of states than the identity theory, and it will also need to invoke more laws of nature, since it seem that to explain the correlations between neural and mental phenomena will require some sort of natural laws linking the two. In general, if we have two theories that explain the same phenomena, we should prefer the simpler one ("Ockham's razor": shave away the unnecessary parts of a theory).
1. correlations between brain states and mental states. Simplest explanation is that they are really the same. (Place: the identities involve the "is of composition": we contingently discover these identities in the same way that we discovered that heat = molecular motion or lightning = electrical discharge.) Note that there appear to be two components to this argument: (a) empirical evidence for correlations between brain states and mental states, and (b) an appeal to simplicity in order to reject the possibility that these correlations are between radically different things. On (b) compare J.J.C. Smart on Occam's Razor at the beginning of his essay, and his discussion of "parsimony and simplicity" at the end of his essay.
Arguments against the Identity Theory
1. Epistemological arguments. (Similar to the epistemological arguments for dualism considered earlier.)
version 1: you can know about mental states without knowing anything about brain states. So by Leibniz' law they can't be the same. This version is vulnerable to the same criticisms we discussed earlier (epistemological properties are relational in a hidden way, so Leibniz's Law doesn't apply to them).
version 2: the identity theory says that we discover empirically that pain = C-fiber excitation (hypothetical example only, not meant as serious neuroscience). But you can discover empirically that X = Y only if you have independent ways of identifying X and Y. But then even if X = Y, the features we use to identify them must be different, leaving us wiith something irreducible.
version 3: I have special access to my mental states in a way I don't have special access to my brain states. So they must be different.
2. Modal argument
- If X = Y, then it is a necessary truth that X = Y.
- I can conceive that M is not identical with P (for instance by imagining a possible world in which one exists and the other doesn't)
- Therefore, it is not a necessary truth that M = P (from 2, assuming conceivability implies possibility)
- Therefore, M is not identical with P (from 1 and 3, by contraposition)
3. Multiple Realization argument
- if mental events are identical with neural events, then nothing that doesn't have a nervous system like ours could have mental events
- it's at least possible that other beings have mental events with different physical realizations than ours
- so mental events can't be type-identical with neural events
Note that argument 3 is compatible with token-token identity, just not with type-type identity.
In a nutshell, the idea that mental states are functional states analyzable in terms of inputs, outputs, and relations to other mental states.
1. Less liberal than behaviorism in attributing mental states, because it takes internal states seriously. (Not so much an argument as an advantage; that functionalism doesn't share a failing of behaviorism is not necessarily a positive reason to think that it is true!)
2. Less chauvinistic than the identity theory: allows that mental states may be implemented by nonhuman creatures. (Again, not an argument so much as an advantage.)
3. In principle, we could represent human sensory inputs, behavioral outputs, and relations between internal states in a giant "machine table" of the same sort used for Turing machines. Such a machine table constitutes a functional definition of internal states (just as the machine table of a Turing machine gives a functional definition of the TM's states). Human mental states correspond to the internal states defined by the "machine table." So human mental states are functional states. (Something along these lines seems to be Putnam's positive argument for functionalism.)
4. Common-sense psychology implicitly defines human mental states in terms of inputs, outputs, and relations to other mental states. So if common-sense psychology is true, then mental states are functional states.
Arguments against Functionalism
1. Absent Qualia (zombie) argument.
2. Inverted Qualia argument.
3. Chinese Room argument.
4. Kim's arguments that functionalism has a difficult time accounting for mental causation (see next section).
II. Mental Causation
The problem of how mental events could cause physical events has traditionally been a problem for dualist theories (ever since Princess Elizabeth raised this as a problem in correspondence with Descartes). Kim suggests that nonreductionist physicalism may also face a problem in explaining how mental events can cause physical events.
Kim discusses three problems of mental causation. All three are summarized on the handout linked above. Especially relevant to the overall train of though we've been following, however, is the problem of mental exclusion, which Kim argues poses a serious difficulty for functionalist (and more generally, non-reductive accounts) of mental phenomena.
Consider a case in which a mental event m of type M causes a physical event p. (Note that lower-case letters represent events, upper-case letters represent types or properties.)
1. p has a complete physical cause c. (causal closure of the physical)
2. c causes its effect by virtue of its physical type C.
3. Even if m = c, M ≠ C. (This follows from nonreductionist physicalism, e.g. functionalism.)
Therefore,
m does not cause p by virtue of its mental type M.
Kim presses this argument further on pp. 198-200 by arguing that if mind-body supervenience holds, then the causal exclusion argument can be extended to show the impossibility, not only of mental-to-physical causation, but also of mental-to-mental causation.
One interesting response to the causal exclusion problem can be found in Stephen Yablo, "Mental Causation," Philosophical Review 101 (1992): 245-280. I summarize it in the last section of http://www.trinity.edu/cbrown/mind/mentalCausation.html.
III. Consciousness
Does consciousness pose a special problem for physicalist theories? How can a physicalist theory account for it?
We discussed Chalmers' distinction between phenomenal consciousness and "awareness." The former involves having qualia or raw feels. The latter is defined in information-processing terms; for a state to be conscious in this sense is for it to be available for use in cognitive tasks such as reasoning and reporting.
The "explanatory gap" is the apparent gap between physical explanations, no matter how detailed, and the phenomenal feel of conscious experience. It is puzzling how the former can explain the latter.
The "hard problem" is the problem of explaining phenomenal consciousness in view of the apparent explanatory gap.
Arguments from absent/inverted qualia. The general idea:
1. I can imagine someone physically identical to me but with inverted (or
no) qualia (e.g. green looks to them as red looks to me)
2. Therefore, it's logically possible for someone physically identical to me
to have different (or no) qualia (from 1)
3. Therefore, qualia don't supervene on physical properties (from 2 and
definition of supervenience)
4. Therefore, physicalism is false (from 3 and the definition of
physicalism)
How can one respond to this? Seems like the only options are (a) deny 1, or (b) deny that conceivability implies possibility, and thus deny that 2 followd from 1.
Kim rather strangely does not discuss the single most-discussed argument about consciousness in the last two decades, the "knowledge argument." However, all of our other books will discuss it!
IV. Mental Content
Reading: Kim, chapter 9. My handout: http://www.trinity.edu/cbrown/mind/kimChapter09.html.
The Main Idea
Many mental states (the "intentional" ones, in the terminology Kim first introduces in Chapter 1) have representational content: they represent the world as being a certain way. Kim addresses two issues about such contents: (1) How do mental states acquire content at all? (2) Is mental content broad or narrow?
How do Mental States Acquire Content?
Three main approaches:
1. Interpretivism: states don't intrinsically have content. Rather, the process of interpretation endows them with content. So the content of my beliefs is just whatever the best interpretation says it is; there is no deeper fact about content. One problem with this view is that it seems to lead to circularity or an infinite regress. If I am to interpret your states as having content, then my own mental states must already have content. If the content of my states, too, simply comes from their interpretation, it's not clear where the original content could come from.
2. The causal-correlational approach. The main idea here is that a mental state has as its content a certain external phenomenon if and only if the state covaries with the phenomenon.
For instance, a certain perceptual state will have the content RED if and only if it is typically caused by red things, and typically is not caused by things that aren't red.
Problems: (1) This has some plausibility for perceptual states, that is, states that refer to directly observable phenomena. It doesn't seem to have any plausibility for states that are about other phenomena: for instance, abstract entities (numbers, sets); theoretical entities (electrons, force fields); or even observable things that we'll never have the opportunity to observe (dinosaurs). The account could still be correct for perceptual states, but if so, we need a way to extend it so as to explain the content of other states also.
(2) Even for perceptual states, if P and Q are reliably correlated, there seems to be no way to distinguish between a representation of P and a representation of Q.
(3) If representations represent whatever they are reliably correlated with, it's puzzling how we could ever misrepresent something. Suppose I have a perceptual state that is triggered by horses. But sometimes it also gets triggered by skinny cows in bad light. In that case, am I misrepresenting a cow as a horse? Or is my representation just a horse-or-skinny-cow-in-bad-light representation?
3. The teleological approach. This can be regarded as a way to solve problems (2) and (3) above. The idea is that a mental representation represents something if it is the function of the representation to indicate that thing. How do things acquire functions? Two ways: in the case of artifacts, they are deliberately designed to function in a certain way, so for example a certain mark on a thermometer represents 80 degrees F because that's what it was designed to represent. Second, in the case of organisms, by virtue of natural selection. If the reason we have a certain representation is because its correlation with P helped our ancestors to survive and reproduce, then it represents P.
Note that the teleological approach (at least in the biological version) only seems to help with representations that are innate. So it can't be a complete account of mental representation, but perhaps it can give an account of basic cases and then we can understand more complex cases as defined in terms of the simple ones.
Is Mental Content Broad or Narrow?
Broad vs. Narrow. A property (or state, etc.) is narrow if and only if it supervenes on the intrinsic properties of the thing which has it. A property is broad if and only if it is not narrow, i.e. if and only if it does not supervene on the intrinsic properties of the thing which has it.
It's hard to give a precise definition of an intrinsic property, but roughly it's a property of an individual that doesn't depend on anything other than that individual. In the case of organisms, it's a property of the organism that depends only on characteristics of the organism from the skin inward. Thus an intrinsic property of an individual must be shared by any exact duplicate of that individual, while an extrinsic property will not necessarily be shared by all duplicates. Example: mass is intrinsic, weight isn't (because an exact duplicate of me on Mars would weigh less).
Arguments that mental content is broad. Putnam offers two reasons for the failure of psychological state to determine reference; each of the two main examples Kim discusses relates to one of these two reasons.
1. The contribution of other people. I don't need to know how to identity what all my terms refer to as long as there are experts around who do. (I can use 'molybdenum' to refer to molybdenum even though I have no idea how to identify samples; I can use 'beech' to refer to beech trees, etc.) This is Putnam's thesis of the "linguistic division of labor." In Kim's chapter, the arthritis example relies on this contribution.
2. The contribution of the environment. Putnam thinks that kinds of things have (or often have) a nature that isn't apparent to casual observation. It may be this hidden nature that determines what some of our expressions refer to, even if we don't (yet) know what this nature is. Most (not all) of Putnam's examples are "natural kind terms," like 'water', 'gold', 'tiger', etc. Where we thing things have a hidden nature we don't know, we often intend to use words to refer to whatever has the same nature as the samples around here. This is basically the thesis Putnam calls "the indexicality of reference." In Kim's chapter, the Twin Earth example relies on this contribution.
V. Reduction and Reductive Explanation
The relation between the Identity Theory and Functionalism is one example of a larger set of issues about what Fodor has called the "special sciences," i.e. sciences that are less general and in a sense at a higher level of abstraction than physics. The positivists thought of all the sciences as being ranged in a hierarchy, with higher-level sciences such as biology being reducible to lower-level sciences such as chemistry. Ultimately, everything would reduce to physics. The Identity Theory is a reductionist theory (claiming that psychological types reduce to neurobiological types), while Functionalism apparently is not, although the issue is tricky (see the discussion of "functional reduction" below). A clearly non-reductionist theory is emergentism.
Two Kinds of Reduction
There are two ways such "reduction" might go. First, higher-level types might be identical with lower-level types. This is what Kim calls identity reduction, and is closely related to the type-type identity theory.
Second, it might be that we can give a functional definition of higher-level types, and then find lower-level types which satisfy the functional definition. This is what Kim calls functional reduction, and is obviously closely related to functionalism. For example, we can give a functional definition of a mouse trap, and then find out which kinds of physical objects satisfy the definition.
Reduction and the Explanatory Gap
If we can give a reductive explanation of consciousness, this would appear to solve the problem of the explanatory gap.
Q: how can we explain why Jones is in pain on the basis of physical phenomena? (This is related to the question: why is pain correlated with neural state N?)
If we can give an identity reduction, then the correct answer is: there are no such correlations, and therefore there is no such gap. If mental phenomena are identical with neural phenomena, then it's false to say that they are correlated: they're just the same thing, so there isn't anything here that needs explanation. Similarly, we don't need an explanation for why Jones is in pain over and above the explanation of why he's in neural state N.
On the other hand, if we can give a functional reduction, then mental phenomena aren't identical with neural phenomena, but they are realized by them. But in this case, it appears that we have a genuine explanation of neural-mental correlations. The explanation goes something like this:
1. functional definition of mental type M: M is a state that is caused by
. . . and is related to other states by . . . and causes . . ..
2. scientific laws: neural state N is caused by . . . and is related to
other states by . . . and causes . . ..
3. Jones is in N
Therefore, 4. Jones is in M
This looks like an explanation of why Jones is in M, provided that we can fill in the details. (The problem is in finding the functional definition mentioned in 1!)
Last update: October 9, 2009.
Curtis Brown | Philosophy of Mind | Philosophy Department
| Trinity University
cbrown@trinity.edu