Brains

Philosophers' Carnival #113

2010-09-02T11:00:00Z

The Demise of "Cognitive Science"

2010-08-26T20:32:00Z

For several years, I've felt that cognitive science as it was originally conceived is being progressively replaced by cognitive neuroscience.

By "cognitive science as it was originally conceived," I mean primarily the alliance between traditional cognitive psychology and artificial intelligence (either "classicist" or "connectionist"), supplemented by contributions from linguistics, philosophy of mind, neuroscience (mostly about "implementation"), and perhaps anthropology.

By "cognitive neuroscience," I mean primarily the study of cognition using behavioral techniques as well as neuroimaging, neurophysiological, and neural modeling techniques, possibly supplemented by contributions from other disciplines such as those listed above--except that instead of traditional artificial intelligence you get more biologically realistic modeling techniques (such as the use of integrate-and-fire neurons).

There are still people who deny the trend from cognitive science towards cognitive neuroscience, or think it's wrongheaded, or think it has no philosophical significance (read: "psychology is still autonomous from neuroscience!!"). But I think any unbiased observer can at least see the trend and suspect that there is something right about it (that is, the replacement of relatively more speculative boxological explanations of cognition with relatively more empirically constrained mechanistic explanations).

I've had a nice direct confirmation of this at the 7th International Conference on Cognitive Science (not to be confused with CogSci 2010 ), which I just attended. Two observations. First, virtually all of the keynote speakers and all the sessions I attended placed heavy emphasis on neuroimaging data, neurphysiology, realistic neural modeling, and other kinds of neurological evidence. Second, two psychologists I spoke to (whose name I unfortunately forgot), one British and one American, explicitly agreed that many scientists who would have called themselves "cognitive scientists" until about ten years ago would be reluctant to use that label now. It seems obsolete to them. And these are the people who attend conferences on "cognitive science"!

Check out Philosophy TV

2010-08-26T20:19:00Z

Philosophy TV is a Bloggingheads kind of deal just for philosophy. It is run (I think) by some grad students at Wisconsin. It apparently goes live on September 6 with Peter Singer and Michael Slote. Then on September 9 it is Andy Egan and Josh Knobe. Alas, it hits a minor bump in the road when Mark Rowlands and I talk about extended cognition on September 16, but I'm sure it will recover.

Realistic [?] Routes to Substrate Independent Minds

2010-08-26T20:04:00Z

Susan Schneider sent me this interesting article about a new group apparently devoted to unifying efforts to build artificial minds.

Incidentally, the article contains a nice series of confused non sequiturs about computation and the brain:

"When it comes to the brain and the mind, the strong neuroscientific consensus is that behavior and experience, phenomena correlated with what we consider the mind, emerge from biophysical functions that are adequately described in terms of classical physics. These processes (and in fact, even quantum physical processes) are computable. It follows that the mind is computable; our brains are machines. The Church-Turing thesis implies that one Turing machine can implement another."

(For an article that attempts to sort out at least some aspects of this kind of mess, see here.)

Update [8/27/10]: a comment by Joshua Stern, saying he is ok with the quoted statements, makes me realize that I need to be more explicit about the problems they raise: (1) whether the mind emerges from biophysical functions that are adequately described in terms of classical physics is actually controversial (this is the least of my worries); (2) it is not clear what the authors mean by "classical physical processes (and even quantum physical processes) are computable"; (3) many disambiguations of the statement in (2) turn out false; the others turn out misleading or trivial; (4) whether something is computable is not the same as whether something is a machine; most relevantly, something may be an uncomputable machine; (5) to claim that the mind is computable because everything physical is computable (whatever that means, see (3), but clearly implying that this is the same as the computational theory of mind) trivializes the interesting empirical hypothesis that the mind has a computational explanation; (6) the final appeal to the Church-Turing thesis is irrelevant, except that in a statement that precedes the quote I give the authors define the Church-Turing thesis in a way that is at best misleading (leading to the fallacy of thinking that the Church-Turing thesis somehow entails that the mind is Turing-computable) and at worse false. Oh, and the transition between the last two sentences sems to equivocally slide between "machine" and "Turing machine".

For more discussions of some relevant issues, see also this, especially Sections 3 and 4.

Best Blog Post of the Year

2010-08-26T18:02:00Z

Nominate your favorite post…details here

Two fronts against Chalmers

2010-08-25T17:41:00Z

In the following I look at two fronts on which you might battle Chalmers' arguments against physicalism about consciousness. The first is from Polgar's recent paper (discussed recently by Richard Brown) in which Polgar briefly critique's Chalmers' implicit theory of reduction. The second is the more common strategy of attacking him for assuming he can conceive of zombies in the first place. I argue that the second strategy is better, though they are not mutually exclusive.

A weaker front: Supervenience and reduction
In his paper Are Sensations Still Brain Processes? Polgar says the following about Chalmers' zombie argument against physicalism:

[T]he a posteriori identity theorist quite reasonably rejects the problematic notion of “logical” conditions and the positivist demand for a special kind of “reduction” of which there are no non-trivial examples and that has long since been rejected by philosophers of science. The burden is on the objector to show independently that the identity theorist, or any physicalist, should require such reductions. And no such positive argument has been given.

Recall Chalmers' argument: if physicalism is true, fixing the values of the physical facts logically fixes the value of the facts about consciousness. This is equivalent to the supervenience claim that different consciousness-facts entail different physical-facts. Note when I say 'physical facts' I mean facts about things in physics, brains, stuff your run-of-the-mill naturalist likes to use as a supervenience base.

It seems, then, that the inchoate view of reduction Polgar refers to is the 'logical fixation' of one set of facts by another. In practice, Chalmers says we need to determine if physical-facts fix consciousness-facts by using a conceivability test. Can we conceive of C-facts shifting while the P-facts stay the same? If so, then physicalism fails.

I'm not sure what is positivisic about Chalmers' view, or what in his view has long been rejected by philosophers of science. Intuitively, he seems right. When we fix the chemical facts we have fixed the higher-level facts about this cup of water (e.g., is it in liquid or solid phase). When the facts about molecules in this gas are fixed, the facts about its temperature, pressure, etc. come along 'for free' so to speak. This seems reasonable, basically a restatement of the claim that consciousness supervenes on the physical.

Based on such considerations, Polgar's claims seem a weak front on which to attack Chalmers' argument, especially when communicating with people that don't know any philosophy. Perhaps a philosopher in the house can clarify or defend what Polgar was saying.

More promising: tempering the conceivability arguments
Another argument against Chalmers accepts his argument strategy, but attacks the high credence he gives his intuitions about how C-facts and P-facts logically relate to one another. How do facts about brains relate to facts about conscious experiences? Our understanding of both sets of facts is so undeveloped that Chalmers' confidence seems premature.

By analogy, many people don't understand how facts about energy relate to facts about mass, they can't conceive of any possible logical route from one to the other. Most people's understanding of energy is about as clear as our present characterization of phenomenal facts, so this seems an apt analogy. While facts about energy don't supervene on facts about mass, that shouldn't change the conceptual point.

The analogy people usually bring up against Chalmers is vitalism. Vitalists couldn't conceive of how physico-chemical facts related to certain biological facts, and used this to infer that the physico-chemical picture of life was incomplete. The vitalist Driesch stated his argument strategy quite nicely when he claimed (in 'Science and Philosophy of the Organism' (1908), p105):

[S]omething new and elemental must always be introduced whenever what is known of other elemental facts is proved to be unable to explain the facts in a new field of investigation.

Driesch's argument for vitalism was an application of that general inference rule. For instance, he argues (ibid, 142):

No kind of causality based upon the constellations of single physical and chemical acts can account for organic individual development; this development is not to be explained by any hypothesis about configuration of physical and chemical agents. Therefore there must be something else which is to be regarded as the sufficient reason of individual form-production...

This is a good example of a conceivability argument hitting the rocks.

Chalmers would likely argue that the analogy fails because in Dreisch's argument the target facts were "easy" facts about development, not "hard" facts about consciousness. This would be to miss the point that we need to exercise extreme caution when consulting our conceptual intuitions about what follows from what. That we now believe one group of facts is easy to reach from the other is clearly a contingent fact.What guarantee can Chalmers offer that he isn't falling victim to a similar failure of imagination, lured by his contingent limited understanding of facts about brains and facts about consciousness?

Conclusion
I don't really buy Polgar's argument, but am willing to be set straight. The more obvious and central problem with Chalmers' arguments is his willingness to take too seriously how he presently conceives of the relationship between two targets that themselves are not particularly well defined. Indeed, we could argue that our present understanding of the two targets is even less well delineated than Driesch's two targets were when he was writing.

Identifying the Identity Theory

2010-08-23T16:00:00Z

Cross-Posted @ Philosophy Sucks!

While I was perusing the new entries over at PhilPapers yesterday I came across Tom Polger's forthcoming paper inPhilosophical Psychology Are Sensations Still Brain Processes? The paper is very interesting (disclaimer: I have a special interest in this stuff; see for instance The Identity Theory in 2-D) and I thought I would summarize its main points and then say something about where we disagree towards the end.

The first part of the paper Polger identifies eight theses that Smart defended in his celebrated paper. These are,

1. Sensation reports are genuine reports

2. Sensation reports do not refer to anything irreducibly psychical

3. Sensations are “nothing over and above” brain processes

4. Sensations are identical to brain processes

5. The identity theory is a metaphysical theory, not a semantic proposal or an
empirical hypothesis

6. Metaphysical theories of the nature of the mind do not make competing
empirical predictions; so they should be evaluated by their theoretical virtues,
e.g., simplicity and parsimony

7. For any thing or kind x, there are “logically” necessary conditions for being a
thing of that kind.

8. Sensation expressions are topic-neutral.

The first claim is simply an endorsement of realism about phenomenal consciousness. Claims 2-4 spell out commitments to physicaism and the identity theory. Claims 5 and 6 spell out Smart's distinctive views about the identity theory. Claim 7 basically asserts that we can know a priori what pains are essentially. Claim 8 amounts to the idea that concepts like 'pain' etc do not entail a commitment to any kind of ontology all by themselves.

Polger goes on to argue that of these every one but 7 should be accepted by contemporary identity theorists. Claim 6 should be accepted but not interpreted too narrowly. The identity theory should be accepted for broadly 'inference to the best explanation' reasons. Parsimony and simplicity play a role in that inference but there are other things that also play a role; As Polger says, "There are also what Jaegwon Kim has called explanatory and causal arguments for the identity theory". The reason that 7 should be rejected according to Polger is the kind of resources that Kripkean arguments give to the identity theorist. In place of 7 above Polger suggests 7*

7*. A Posteriori. The identity of sensations and brain processes is a posteriori

7* is then an updated version of Smart's claim that mind/brain identities are to be construed as ordinary scientific identities. We now have a post-Kripkean understanding of these kinds of identities and the contemporary identity theory should reflect that.

In the second part of the paper Polger goes on to formulate a master argument against the identity theory that he thinks subsumes all arguments against it and then responds to the various particular objections. The master argument goes as follows;

(P1) If the identity theory is true, then there is a necessary one-to-one relation between sensations and brain processes.15 (necessity of identity)

(P2) If VARIATION then there is not a necessary one-to-one relation between sensations and brain processes. (definition of VARIATION)

(P3) VARIATION.

(P4) There is not a necessary one-to-one relation between sensations and brain processes. (P2, P3)

(C2) The identity theory is false. (P1, P4)

The particular objections that we find spell out varieties of variation claims: actual, nomological, metaphysical, logical. Polger identifies one major figure and style of objection this way. So, Putnam's worries about octopi and Fred's pain at 6:00 v.s. Fred's pain at 6:15 count as actual variation while Fodor's worries count as nomological, Kripke's modal argument is metaphysical, and Chalmer's zombie argument is logical. All of these arguments are united by trying to show that there is or can be variation.

Polger has a lot of interesting things to say in response to each of these objections. Against actual variation he argues that even if we grant, as we might not, that we find the very same psychological properties across species on Earth (that is to say, even if an octopus can feel the very same kind of sensation that I do when I experience pain) there is still very little reason to think that psychological properties are multiply realizable in a way that is threatening to the identity theory. Sure there may be differences between species but that is no reason to rule out similarities a priori! Some people cite neural plasticity as a possible source of trouble. To this Polger replies, "evidence from plasticity is compatible with the neurobiological variations being variants within a more general kind that is also neurobiological." Lacking any reason to believe in actual variation we also have no reason to believe in nomological variation, what about metaphysical variation? Here Polger endorses type-b physicalism and argues that Kripke's argument is question begging. If the mind-brain identities are true then they are necessarily true. This leads Polger to the last kind of variation which he calls logical variation. It is here that we find Polger's discussion of Chalmer's zombie argument. His main complaint is that the argument rests on an assumption about the nature of reduction that the type-b physicalist will reject.

In the final section of the paper Polger introduces two further claims which he thinks should be endorsed by contemporary identity theorists.

9. Variability. Sensation processes are multiply constituted.

10. Strong Physicalism. Physicalism is necessarily true; all worlds are physicalist worlds.

In defense of accepting 9 Polger argues as follows,

accepting that there is...variability in the world is a far cry from accepting that it is the kind of variability that would be problematic for identity theories. Identity theories claim that sensations are brain processes, but they do not take any stand on the nature of brain processes. In particular, the identity theorist need not suppose that the world is organized into homogeneous columns of organization so that there is a one-to-one relation between sensations and microphysical processes. The identity theorist identifies sensations with brain processes, not with molecular or subatomic processes that occur inside brains.

I have always been sympathetic to this kind of argument and have seen some of my own work as generally supporting it. But what about 10? Why ought we accept that? The basic reason is to avoid the following reductio of the identity theory;

C1. Sensations are identical to brain processes in all possible worlds. (identity theory)

C2. Physicalism is contingent; there are some non-physicalist worlds containing non-physical sensations. (contingent physicalism)

C3. There are some worlds in which sensations are not identical to brain processes. (from C2)

C4. The identity theory is false.

Polger's answer to this argument is to give up C2 thereby blocking C3. This may seem dramatic and I take 10, together with 7*, to entail that there are strong necessities in Dave Chalmers' sense, "but", says Polger, "so it goes. Just as there are necessary a posteriori truths, there are necessary a posteriori falsehoods."

But it is just at this point that the difference between the kind of identity theory that Polger has and one that is in 2-D. Once we start thinking in 2 dimensional semantics we can see an equivocation in the redictio. C1 should be modified as C1*

C1* The secondary intension of 'Sensations are brain processes' is necessary; the primary intension of 'sensations are brain processes' is contingent (identity theory in 2-D)

Once we do that we do not have the worry about the reductio. Adopting C1* is tantamount to a compromise between 7 and 7*. In effect we agree that there is an a priori knowable description or reference fixer and an a posteriori identified physical state. Given that we know independently that identities like this are 2-necessary in Dave Chalmers' sense we can conclude that those identities are necessary in spite of possible worlds where the a priori knowable description picks out a non-physical property.

Dialogue Symposium on Doing without Concepts

2010-08-17T17:01:00Z

Dialogue will publish soon the symposium on Doing without Concepts with Tania Lombrozo's, Pierre Poirier's and our own Gualtiero's papers. (Gualtiero's paper was posted on this blog earlier and was followed by a lively exchange.) The three papers are really excellent and worth reading.

My reply is here. Part of it is in French, since Dialogue is a bilingual journal. But some of you might be interested by reading what I have to say, particularly if you have read Gualtiero's paper beforehand.

Cheers

Edouard

PS: Doing without Concepts is now at $45 on Amazon (from $52 a few days ago). If you have not bought it yet, but plan to do it, this might be a good occasion.

Sterelny on the evolution of humans

2010-08-16T18:31:00Z

Some of you might be interested by Kim Sterelny's essay on the evolution of humans and by the commentaries on his essay (C. Driscoll, P.S. Davies, mine, etc.). It's a good summary of Kim's views. The symposium is organized by C. Driscoll on the forum On the Human.

Edouard

Philosophers' Carnival #112

2010-08-10T15:08:00Z

Here .

The Journal of Visualized Experiments

2010-08-10T14:56:00Z

This website was just brought to my attention. It is the Journal of Visualized Experiments (JoVE), an “online research journal employing visualization to increase reproducibility and transparency in biological sciences”. It’s interesting and potentially quite useful. Does anyone have any thoughts on it?

Do Philosophers Rank their Journals?

2010-08-08T18:12:00Z

A while ago Mark Couch alerted me to an article by Jeffrey Di Leo in Inside Higher Ed. Di Leo's thesis is this:

"It is one sign of the good health of the humanities that they have not caught rank and brand fever like many of the other disciplines in the American academy. Whereas one can readily find rankings of science or business journals, there is silence when it comes to rankings of humanities journals."

Although Di Leo makes some good points--e.g., that it is difficult to rank together journals that specialize in different areas of philosophy and that good work may be published in lesser known journals--his main premise is completely backwards. Most surprisingly, his main example of a humanity discipline is philosophy!

I can't speak about other humanities. But philosophers definitely do rank their journals (here is a recent example) and more importantly, they pay a lot of attention--sometimes too much attention--to where their work is published.

Contrary to what Di Leo argues or implies, my experiences suggests that by and large, within mainstream philosophy departments decisions about awards, grants, hires, and promotions are heavily influenced by where people publish. The "better" the journals where someone has published, the better her chances to be hired, promoted, and given grants or awards.

Ranking journals and paying so much attention to where someone publishes creates some distortions, of course. Where someone's work is published is at best a coarse and somewhat unreliable measure of its quality, yet people often take that shortcut (which in many cases is a necessary shortcut for lack of time or expertise). Furthermore, acceptances at the best journals are almost certainly biased at least somewhat in favor of people who work at the best philosophy departments (in spite of double blind refereeing, where it is done).

Nevertheless, journal rankings are useful if used with the proverbial grain of salt. Publishing in, say, Phil Review doesn't make anyone a genius, and publishing in the Journal of Inferior Philosophy doesn't make anyone an inferior philosopher. But a journal will not be ranked high forever if its quality declines. Witness that many philsophers now consider J. Phil (which ten years ago was still considered #1 or at worst #2) as lower than Phil Review, Nous, and Philosophers' Imprint. That being the case, whether a paper is published in a good journal is a very useful indicator of its likely quality--not to mention, of how many people will read and cite it.

Can You Make a Conscious Machine?

2010-08-04T17:20:00Z

I am writing a thesis on the possibility of machine consciousness (e.g., the possibility of creating a silicon-based system that has subjective, qualitative experiences in the same way we take ourselves to have them). In my informal (and very limited) polling, it seems that many philosophers are sympathetic to the project.

However, not all functions can be realized by all structures (e.g., you can’t make a car out of paper towels). Given the many fundamental asymmetries in structure between humans and silicon-based systems, it is at least plausible that human consciousness cannot be realized in silicon-based structures.

Of course, proponents of machine consciousness will reply that the properties relevant to consciousness are multiply realizable, but do they have any evidence?

I was wondering what others take to be the strongest arguments either for or against the possibility of machine consciousness. What is the strongest reason to think human consciousness is realizable in silicon? And what is the strongest reason to think it is not? Centrally, what aspect(s) of a putative realizer seem most relevant to realizing human-like consciousness?

Knowing That P Without Believing That P

2010-08-03T22:29:00Z

For those interested, Eric Schwitzgebel and I have been exploring the relationship between knowledge ascriptions and belief ascriptions. We just finished a draft on this topic, which can be found here.

Abstract:

The standard view in contemporary epistemology is that knowledge entails belief. Proponents of this claim rarely offer a positive argument in support of it. Rather, they tend to treat the view as obvious, and if anything, support the view by arguing that there are no convincing counterexamples. We find this strategy to be problematic. In particular, we do not think the standard view is obvious, and moreover, we think there are cases in which a subject can know some proposition P without (or at least without determinately) believing that P. In accordance with this, we present four plausible examples of knowledge without belief, and we provide empirical evidence which suggests that our intuitions about these scenarios are by no means atypical.

Comments are welcome.

[Cross-posted at Experimental Philosophy and The Splintered Mind]

Aizawa on Turing-Equivalent Computation and Cognitive Science

2010-08-02T20:29:00Z

In a previous thread, Ken Aizawa suggests that I'm insufficiently pluralistic about computation in cognitive science and to substantiate his criticism he points to his forthcoming article "Computation in Cognitive Systems; It's not al about Turing-Equivalent Computation" (available on his website).

Having read Ken's nice paper, I only have time for a few quick comments.

1. Ken correctly points out that there are several notions of computation. (I make the same point in a paper that he refers to.)

2. Ken correctly points out that many people including myself think there is something special and theoretically deep about what he calls Turing-equivalent computation, by which he seems to mean the kind of computation that can be performed by Turing machines (computation of Turing-computable functions). They're right, because in fact this is the core theoretical notion of computation, with lots of deep results about it.

3. Ken correctly points out that the notion of Turing-computable functions can be generalized to study functions of natural numbers (or equivalently of strings of letters from a finite alphabet) that are not computable by Turing machines. This enterprise was started by Turing himself and is a large branch of computability theory. (Anyone who takes a nontrivial course in computability theory knows this.) But contrary to what Ken seems to suggest, the study of functions that are uncomputable by Turing machines is not based on a different notion of computation from that of Turing machines--it's the very same notion; in fact, the whole subject matter is defined in terms of functions that are like those computable by Turing machines but cannot be computed by Turing machines.

4. Ken persuasively argues that Turing machines and the related notion of computabiltiy probably played only a minor role in McCulloch's thinking at the time he wrote his 1943 paper with Pitts. But Ken seems to underestimate the theoretical significance of computation-theoretic results in characterizing the power of McCulloch-Pitts nets and other neural networks. (The latter obviously is not discussed in the 1943 paper.) Ken also seems to underestimate the important role that the connection between McCulloch-Pitts nets and Turing-computability played in the history of cybernetics and cognitive science. For the beginning of an account of that history, based on extensive archival research, see Chapters 5 and 6 of my Ph.D. dissertation.

5. Ken asserts that the notion of "computed vs. uncomputed cortical maps" deployed by some neuroscientists "is not a Turing--equivalent form of computation" (p. 17). But I didn't notice anything in Ken's paper that determines what relationship there is or isn't between the notion of computation deployed in this area of neuroscience and Turing-computabilitiy, so I don't know why Ken is so confident in his assertion.

6. Ken also points out that often cognitive scientists talk about computation as symbol manipulation or digital symbol manipulation, without mentioning the kind of "finitude constraints" that are important to Turing-computability. This is true but doesn't mean that the finiteness constraints are not implicitly assumed to be in place (except by people like Jack Copeland); after all the brain has only a finite number of neurons etc.

7. Ken's pluralism seems to be based on something like the following argument: if scientist A uses "computation" in pursuit of goal X and scientist B uses "computation" in pursuit of goal Y and X is different than Y, than scientists A and B use two different notions of computation. This is a fallacy. Maybe there are two different notions of computation, maybe they aren't. It takes a lot more than this to show that two notions of computation are the same or different. More generally, it takes a lot of theoretical work to compare and contrast different notions of computation and see how they relate to one another. That's why, contrary to what Ken suggests, it's very helpful to have an umbrella notion of computation, of which other notions (including all those mentioned by Ken) are species.

8. In conclusion, reading Ken's paper convinced me that I have just just the right kind of pluralism for sorting out competing claims about computation in cognitive science.

Information Processing, Computation, and Medium Independence

2010-07-30T15:52:00Z

In response to a previous thread, Jonathan Livengood asked some very good questions about, roughly, what should count as information processing and computation in physical systems. Perhaps it will help to take a step back.

In my early work on computation, I argued that, roughly, only physical processes that take strings of digits as inputs and return strings of digits as outputs by following a rule defined over the inputs (and possibly internal states) count as computing systems . My reason had to do with the centrality of the formalisms of computability theory to the notion of computation. As to analog computers, which do not manipulate strings of digits but are still called computers, I argued that they are "computational" only by courtesy and for contingent historical reasons .

I later realized that, although there was something right about my early purism about computation, it was unhelpful to try to restrict the notion of computation to digital computation in the face of important yet broader uses of the term "computation" in many sciences, including neuroscience. (BTW, I had this realization in time to dodge Ken Aizawa's criticism that I was insufficiently pluralistic; Ken's criticism does apply to my former self, though.).

After that, I needed to characterize a notion of computation more general than that of digital computation (without appealing to representation, of course, otherwise I would have gone against one of my core views about computation ).

What came to my rescue is the notion of medium independence. Medium independence was introduced by Justin Garson in his 2003 MA thesis, part of which was published in a beautiful and underappreciated article in Philosophy of Science on "The Introduction of Information in Neurobiology ".

Justin pointed out that the first person to talk about neural systems transmitting information was Edgar Adrian (1928), on the grounds of his groundbreaking discovery of some crucial properties of neural signals ("all or none", "rate coding", and "adaptation"). Justin reconstructed Adrian's notion of information as involving medium independence:

"Medium independence: The structure S--for example, the structure relation that obtains between the units of a sequence of action potentials--can be instantiated across a wide range of physical mechanisms." (Garson 2003, p. 927)

While Justin's medium independence is not necessary for carrying (natural) information in the usual sense, a slightly modified version of it seems well suited for characterizing the general notion of computation. So in my more recent work, I characterize computation in the generic sense as (roughly) the functional manipulation of medium independent vehicles according to rules, where a variable is medium independent just in case it is manipulated on the grounds of similarities and differences between its parts along a certain dimension of variation, irrespective of its more concrete physical properties.

Example 1: various sensory receptors transduce all kinds of physical variables into spike trains, which are then conveyed to the nervous system, which in turn manipulates these spike trains. This was one of Adrian's amazing discoveries: neural fibers carry the same kind of signals regarless of their physical inputs. Thus, neural processes are computations in the generic sense.

Example 2: computers manipulate strings of digits, which are well defined so long as there are distinguishable types and an ordering relation, regardless of the details of their physical implementation. The same digital computation can be performed in mechanical, electronic, electromechanical, etc. media. Thus, the activity performed by digital computers are computations in the generic sense (and digital computation is a species of computation in the generic sense).

Example 3: mutatis mutandis, analog computers manipulate their own type of medium independent vehicles. Thus, analog computation is a kind of generic computation.

I hope someone can see the beauty of this. We now have an explicit, non-semantic characterization of computation in general, of which analog computation, digital computation, etc. are species. Thanks Justin!

Anyway, then there is the question of information processing. Obviously information can be "processed" in a medium dependent way, as done by the Watt governors or float regulators that we've been discussing. If Jonathan insists in calling this type of thing information processing, so be it. But information processing can also be done in a medium independent way, and IMO that's what most people mean when they talk about information processing. In any case, if you care about what does and does not compute it's important to notice the difference between the two cases, because medium-dependent information processing does not entail computation whereas medium-independent information processing does entail computation.

A Response to Machery's Response

2010-07-28T15:39:00Z

The latest issue of BBS includes a précis of Edouard Machery's Doing Without Concepts —the book that boldly argues that the term "concept" should be eliminated from psychology. The fourth tenet of Machery's Heterogeneity Hypothesis (HH) proposes that prototypes, exemplars, and theories —three types of concept —are used in distinct cognitive processes. Gualtiero Piccinini and I wrote a short response arguing that Machery has not provided enough evidence that prototypes and exemplars are used in distinct cognitive processes. If we are right, then Machery's argument for concept eliminativism as he presents it doesn't go through.

Interestingly, Machery chooses to respond to us by weakening his argument. Machery maintains that even if exemplars and prototypes are used in the same cognitive processes, theories are used in different cognitive processes from exemplars and prototypes. Thus, Machery concludes, "there are no generalizations about how concepts are used in cognitive processes" (2010, 237).

But Machery's response is less satisfying than it may appear. Our commentary focused on prototypes and exemplars because that's where Machery made his strongest case for differences in the cognitive processes. Machery offers little, if any, support for the claim that theories are used in distinct cognitive processes from prototypes and exemplars. In fact, everything Machery says is consistent with the hypothesis that theories are prototypes plus some causal information of a category (incidentally, many psychologists also believe that theories are enriched versions of prototypes). If theories are just augmented prototypes (i.e., a kind of prototype), then a fortiori they are used in the same cognitive processes. The burden is on Machery to provide evidence that theories are truly distinct from prototypes and are used in distinct cognitive processes.

Unless, of course, theories are seen as what Piccinini (forthcoming) calls "linguistic concepts".

14TH CONGRESS OF LOGIC, METHODOLOGY AND PHILOSOPHY OF SCIENCE NANCY, JULY 19-26, 2011

2010-07-28T11:24:00Z

I know that most folks get their conference CFPs, etc. from other sources, but this one seems to me a) to be flying a little low on the radar and b) to be pretty cool. I went to one of these a long time ago in Florence, which was both a very good conference, and a truly amazing world class city. It would be great to have a good representation of brains readers. (I've already submitted my abstracts, but don't let that deter you.)

Check it out here .

A New Account of the Systematicity of Thought

2010-07-27T13:52:00Z

In other Aizawa-relevant news, Steven Philips and Williams Wilson have a new theory of the systematicity of thought based on category theory.

With their publication, they have joined an elite group of academics who have referred to my book, The Systematicity Arguments. (Fodor mentions it in LOT 2 and McLaughlin mentions it in his "Systematicity Redux" .) Indeed, Philips and Wilson do more than just mention the book. They have an entire section of largely positive discussion some of the material. The material is probably off the radar of most philosophers in the PLoS Computational Biology, but it is freely available.

http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000858 (HTML)

http://www.ploscompbiol.org/article/fetchObjectAttachment.action?uri=info%3Adoi%2F10.1371%2Fjournal.pcbi.1000858&representation=PDF (PDF)

http://www.ploscompbiol.org/article/fetchObjectAttachment.action?uri=info%3Adoi%2F10.1371%2Fjournal.pcbi.1000858&representation=XML (XML)

I'm sure my royalties for that book will now be waaay more than ten dollars for this year.

Subtyping and Multiple Realization

2010-07-27T10:44:00Z

As many of you may know, I have been thinking about the following problem for a while:

Suppose that scientists discover a high level property G that is prima facie multiply realized by two sets of lower level properties, F1, F2, …, Fn, and F*1, F*2, …, F*m. One response would be to take this situation at face value and conclude that G is in fact so multiply realized. A second response, however, would be to eliminate the property G and instead hypothesize subtypes of G, G1 and G2, and say that G1 is uniquely realized by F1, F2, …, Fn, and that G2 is uniquely realized by F*1, F*2, …, F*m. This second response would eliminate a multiply realized property in favor of two uniquely realized properties A third possible scientific strategy would be to keep G and add subtypes G1 and G2. What do scientists actually do?

With Carl Gillett, I've been arguing, in essence, that scientists take door #1. This answer is defended in a forthcoming paper with Carl, "The Autonomy of Psychology in the Age of Neuroscience" , In Illari, P.M., Russo, F., and Williamson, J. Causality in the Sciences. Oxford University Press.

It has recently come to my attention that Michael Esfeld, Christian Sachse, and Patrice Soom have been developing views (roughly) along the lines of door #3. See, for example,

"Theory Reduction by Means of Functional Sub-Types"

Reductionism in the Philosophy of Science.

"Functional Subtypes" .

Esfeld and Sachse also have a book forthcoming from Routledge developing a version of door #3.

I'm reading through their stuff now, but the most jarring thing for me is that they claim that they are exploring subtyping as a logically possible thing for scientists to do. But, if this is merely a logically possible thing for them to do, and not something they actually do, then why think this has much to do with science or reduction?

All that's rough, but take this post as a trailer for this topic.