Neurodynamicsand Causality

Parmenides Workshop Elba, May 22, 2008

Godehard Link

Seminar of Philosophy, Logic and

Philosophy of Science

Faculty of Philosophy, LMU Munich

2

Overview

1. Introduction 2. Ontology 3. Reduction4. Causation5. Downward Causation6. Naturalism Reloaded: Neurodynamics7. And What About Free Will?8. Conclusion

3Emil du Bois-Reymond

4

Emil du Bois-Reymond on Matter and Mind

Und es wäre natürlich ein hoher Triumph, wenn wir zu sagen wüssten, dass bei einem bestimmten geistigen Vorgang in bestimmten Ganglienkugeln und Nervenröhren eine bestimmte Bewegung bestimmter Atome stattfinde[;] ... oder wenn wir auch nur wüssten, welcher Tanz von Kohlenstoff-, Wasserstoff-, Stickstoff-, Sauerstoff-, Phosphor- und anderen Atomen der Seligkeit musikalischen Empfindens, welcher Wirbel solcher Atome dem Gipfel sinnlichen Geniessens, welcher Molecularsturm dem wütenden Schmerz beim Misshandeln des N. trigeminus entspricht.

Über die Grenzen des Naturerkennens, 1879

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Du Bois-Reymond‘s Ignorabimus

Gegenüber den Räthseln der Körperwelt ist der Naturforscher längst gewöhnt, mit männlicher Entsagung sein „Ignoramus“ auszusprechen. Im Rückblick auf die durchlaufene siegreiche Bahn trägt ihn dabei das stille Bewusstsein, dass, wo er jetzt nicht weiss, er wenigstens unter Umständen wissen könnte, und dereinst vielleicht wissen wird. Gegenüber dem Räthsel aber, was Materie und Kraft seien, und wie sie zu denken vermögen, muss er ein für allemal zu dem viel schwerer abzugebenden Wahrspruch sich entschliessen: „Ignorabimus!“

Über die Grenzen des Naturerkennens, 1879

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Du Bois-Reymond‘s Message

Du Bois-Reymond, a leading physiologist of his time, refuses – unlike Häckel, for instance – to speculate on what he perceives as metaphysical matters: the essence of matter, of force, and „how matter is able to think“; he concludes that we will „never know“. It is the scientific attitude in view of the immense gap between his practice as a scientist and the deep questions he speaks about, even if we now see that he was proven wrong at least in the case of matter and force where we have a pretty good understanding now with the advent of modern physics.

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Formal Ontology: Basic Tools

• Predication

• Existence

• Identity

• Abstraction

• Mereology

• Modality

• Reduction

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Predication

• Basic tool for making judgments about the world- Categorization, conceptualization, subsumption

- Basis in evolution

• Reality of concepts non-issue in science:realism regarding universals taken for granted

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Existence• What are the objects making up the

world?- thing or event language in science?

• Trade-offs- things, facts, states of affairs, properties, events, processes (there are subtle logical differences)

- important logical relation: subsuming thing-processes under a typeexpressed by a predicate in a language

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Identity

• Sharp only in theory (set theory)

• Identity is theory-dependent

- e.g.: classical statistics vs quantum

statistics

Boltzmann, Bose-Einstein, Fermi-Dirac

• Identity is time-dependent

- creation, annihilation, change of identity

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Mereology

The pyramid basis for

nominalism:

all objects

of same kind

x

y

x y

x o y

x y

Mereological fusions are ontological free lunchesNo paradigm for complex physical objects

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Reduction

In Logic:

Relative Interpretation between Theories S, T:Translation plus Derivation

Example: PA into ZF set theory:• 0 becomes the empty set • Successor function becomes x { }• less-then < becomes • then the translations of the Peano axioms are derivable in ZF relativized to the set of finite ordinals ; see next slide for a picture

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The Universe of Sets

V0= Ø

V6

Vω

Vω+ω

ω

θ Vθ

usualmathematics

the finite

classicalset theory

(Zermelo, Fraenkel;v.Neumann, Gödel)

V6 has 1020000 elements

domain of largecardinals

ω א

Ω

θ smallestinaccessible

cardinal

ω+ω1א

the transfinite

N the natural numbers

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Strawman Reduction: Nagel reduction

Nagel reduction vs relative interpretationsimplest way: S is a subtheory of a definitional extension of T: S TBut that is the result of Nagel reduction only if the bridge laws A B are interpreted as definitions; but Nagel takes those “links” as he calls them either as meaning postulates, analytic entailments, coordinating definitions or merely hypotheses supported by empirical evidence.

d

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Merits of reduction

• Generalization• Unification• Understanding a theory in the light of another which is already understood• Modeling concepts of one theory with those of another• Giving inner models (e.g. a model of hyperbolic geometry within euclidean geometry: the „beercoaster geometry“)

Benefit: Structural insights

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Problems with Reduction in the Hierarchy of Sciences

V. Weisskopf (1965): intensive vs extensive research. But P. Anderson: This is particle-physicists’ fundamentalism

The main fallacy of this kind of thinking is that the reductionist hypothesis does not by any means imply a „constructionist“ one: The ability to reduce everything to simple fundamental laws does not imply the ability to start from those laws and reconstruct the universe. ... The constructionist hypothesis breaks down when confronted with the twin difficulties of scale and complexity. The behavior of large and complex aggregates of elementary particles, it turns out, is not to be understood in terms of a simple extrapolation of the properties of a few particles. Instead, at each level of complexity entirely new properties appear.

Philip Anderson („More is Different“ Science 1972)

1717

SubstanceDualism

Physicalism:Substance

Monism

PropertyDualism

Non-ReductivePhysicalism

Physicalism:PropertyMonism

QualiaPhenomenalism

PlainPhysicalism

Reduction in thePhilosophy of Mind

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Bennett/Hacker on What-It-Is-Like-ism*

A short note on qualia: if they are reified they become highly problematic philosophically. After a critical discussion of qualia, Bennett and Hacker (Philosophical Foundations of Neuroscience, PFN) conclude:

“it is wrong for Nagel to suggest that ‘we know what it is like [for us] to be us’ ... [I]t is mistaken of Edelman and Tononi to assert that we all ‘know what it is like to be us’, ... [a]nd it is a confusion to think, as Searle does, that for any conscious state, ‘there is something that it qualitatively feels like to be in that state’” (BH,PFN:281).

*) My term; G.L.

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Reduction in the Philosophy of Mind

The following slides give typical principles and theoretical tools that are used in the literature of the philosophy of mind

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Perception

Problematic views:

• „Interface“ view of perception: you are not perceiving objects directly, but „sense data“

• Representationalist theory of the mind (RTM) and computer functionalism; but here is a lesson from history:

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Hacker on the Computer Analogy of the Mind

“[T]he growth of computer science exercised an irresistible fascination. Where our ancestors had pictured themselves in the image of God, it was now tempting to picture ourselves in the image of our machines. And a double irony ensued. The gods were conceived as creating us in their image, whereas we created them in ours. We invented machines to do automatically what we do thoughtfully, and then proceeded to conceive of ourselves on the model of our automata.” (WAP:271)

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Identitiy Thesis (D. Lewis)

Mental state M = the occupant of the causal M-role (by analysis)

Physical state P = the occupant of the M-role (by science)

Therefore M = P

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Supervenience Thesis

No change in mental states without a change in their underlying physical states

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Internal Supervenience Thesis

Every internal psychological state of an organism is supervenient on its synchronous internal physical state.

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Explanatory Thesis

Internal psychological states are the only psychological states that psychological theory needs to invoke in explaining human behavior – the only states needed for psychology.

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Putnam against Kim

Kim’s strategy of defining a “core state” is doomed to failure:

“The futile search for scientific objects called ‘narrow content’ in the case of meaning and for ‘internal psychological states’ in the case of beliefs are alike instances of the rationalist error of assuming that whenever it is natural to project the same words into two different circumstances there must be an ‘entity’ that is present in both circumstances.” (P:3C:125)

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Psychophysical Correlation Thesis (PCT)

For each psychological event M there is a physical event P such that, as a matter of law, an event of type M occurs to an organism at a time just in case an event of type P occurs to it at the same time.

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Putnam on the PCT

P argues against the picture presupposed by PCT, viz., our psychological states are internal states which, qua internal, must be correlated with specific bodily processes.“Our psychological characteristics are, as a rule, individuated in ways that are context sensitive and extremely complex, involving external factors (the nature of the objects we perceive, think about, and act on), social factors, and the projections [in Stanley Cavell’s sense in The Claim of Reason (P:3C:125)] we findit natural and unnatural to make.” (3C:132)

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Putnam on reductionism

Putnam claims that even reductionism can be used against the intelligibility of the Automatic Sweetheart scenario without being committed to the utopian program of reducing mental properties to physical ones.

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Putnam on reductionismcont‘d

“The materialists are right to insist on our embodied nature; they are right to insist that the connection between mind and body is too intimate for talk of disembodied spirits, Automatic Sweethearts, the ‘soulless tribe’, and so on, to get off the ground; but they are wrong when their scientism drives them to claim that we can only think of our mentality as something that acts in and through our bodies if we can reduce the terms of the vernacular psychology to terms of chemistry, physics, neurology, computer science, etc.” (3C:149f.)

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Causality

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Causality

Substantial Causes: Aristotle

Four causes: material, formal, efficient, final

Final causes account for regularities in nature (~ laws): against Demokriteans

For Aristotle, finding causes was explaining things !

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Ways of Evading Substantial Causality

• Instrumentalism• Psychological associations (Hume)• Regularity View• Probabilitistic conceptions: correlations

(„contingency tables“)• Obsolete in physics: B. Russell‘s dictum;

Wheeler‘s „It from bit“ mixing ontology with epistemilogy

• Explanatory causality

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Feynman on instrumentalist QED

In the wild an wonderful world of quantum physics, probabilities are calculat-ed as the square of the length of an arrow: where we would have expected to add the probabilities under ordinary circumstances, we find ourselves „adding“ arrows; where we normally would have multiplied the probabilities, we „multiply“ arrows. The peculiar answers that we get from calculating probabilities in this manner match perfectly the results of experiment. I‘m rather delighted that we must resort to such peculiar rules and strange reasoning to understand Nature, and I enjoy telling people about it. There are no „wheels and gears“ beneath this analysis of Nature; if you want to understand Her, that is what you have to take.

R. Feynman, QED. The Strange Theory of Light and Matter, p.78

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Causation

David Hume (Treatise of Human Nature 1739):“Thus we remember to have seen that species of sensation we call flame, and to have felt that species of sensation we call heat. We likewise call to mind their constant conjunction in all past instances. Without farther ceremony, we call the one cause and the other effect, and infer the existence of one from the other.”

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Causation

B. Russell, On the notion of cause (1913):“All philosophers ... imagine that causation is one of the fundamental axioms or postulates of science, yet, oddly enough, in advanced sciences ... the word ‘cause’ never occurs. ... The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.”

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J. Wheeler‘s „It From Bit“

[E]very it – every particle, every field of force, even the spacetime continuum itself – derives its function, its meaning, its very existence entirely ... from the apparatus-elicited answers to yes or no questions, binary choice, bits. It from bit symbolizes the idea that every item of the physical world has as bottom ... an immaterial source and explanation; that what we call reality arises in the last analysis from the posing of yes-no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and this is a participatory universe.

From: „It From Bit“, in: J. Wheeler: At Home in the Universe

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Causation

H. H. Pattee (Andersen et al: 68) speaks of causes as controllable features. But not everything can be subjected to controlled experiments in a laboratory.

Perhaps more apt is the idea of intervention which can be due to either human action or else natural processes (e.g. an earthquake causing a desaster)

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Causal FlowI’d like to stick to real causes and not equate them with explanations: the leading picture is causal flow along a gradient

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Explanation

An influential strategy is to give reasons instead of causes.

But there is a reason for explanation: Explanations provide stable reasons deriving from underlying causal mechanisms.

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Downward Causation

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Kim‘s Exclusion Argument

Problem of mental causation: Causal efficacy of mental properties is inconsistent with the conjunction of the following four principles: CC + CE + MBS + PD:

• CC physical causal closure • CE causal exclusion• MBS mind-body supervenience• PD mental/physical property dualism

Kim: Only negotiable item is the fourth principle PD; if it goes we are back to physicalism; no DC

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Sperry‘s Wheel Metaphor

“The subjective mental phenomena are conceived to influence and govern the flow of nerve impulse traffic by virtue of their encompassing emergent properties. Individual nerve impulses and other excitatory components of a cerebral activity pattern are simply carried along or shunted this way and that by the prevailing overall dynamics of the whole active process (in principle – just as drops of water are carried along by a local eddy in a stream or the way the molecules and atoms of a wheel are carried along when it rolls down hill, regardless of whether the individual molecules and atoms happen to like it or not). ... The neurophysiology, in other worlds, controls the mental effects, and the mental properties in turn control the neurophysiology.” [after Kim in Andersen et al: 312f]

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Kim‘s argument against Sperry

Kim abstracts from this the following dual principle:

• Downward causation plus upward determination

But he doubts the coherence of maintaining both principles simultaneously.

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Downward Causation plus Upward Determination (DwC + UpD)

at t

a

W having M at t

causes

t fixed

WCollectiveUpward Determinationof W by the a‘sat t

having P at t

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Kim‘s argument against Sperry

Kim argues with the following principle:

Causal-power Actuality Principle: For an object, x, to exercise, at time t, the causal/determinative powers it has in virtue of having property P, x must already possess P at t. When x is being caused to acquire P at t, it does not already possess P at t and is not capable of excercising the causal/determinative powers inherent in P. (Kim:315)

Since causation is not instantaneous, DwC + UpD is untenable, given Kim‘s principle.

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Alwyn Scott‘s evaluation ofKim‘s argument

Scott on Kim (NSciP:304): That’s an unrealistic static view! The x and P above are really functions of time: x(t), P(t), and as such obey some dynamic regularity, say

d/dt x(t) = F(x,P)d/dt P(t) = G(x,P)

with F and G some some nonlinear functions of x and P. The emergent structures are not represented by x(t) and P(t), but by some asymptotically stable solutions x0 and P0 satisfying the system

0 = F(x0,P0)0 = G(x0,P0)

Thus x(t) x0, P(t) P0 , for t

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Logistic growth

# molecules (N)

Rate of increase dN/dt

Verhulst equation

dN dt

= N(1 N/No )

NoN(0)et

N(t) =No + N(0)(e 1)t

Not

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Verhulst functions with attractor

t

N(t)

No

50

Closed Causal Loops

Release of Energy

Dissipation of Energy

51

Neurodynamics

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Downward Causation

3 Concepts (Emmeche et al.): Week, Medium, Strong

• WDC: Molecules of an organism are governed by some non-linear dynamics with attractors and corresponding basins of attraction• MDC: WDC plus: emergent higher-level structures can modify the properties of their parts: e.g., through closes causal loops • SDC: MDC plus: upper level phenomena can modify the physical and chemical laws governing their constituents

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Freeman on Assimilation

“The body does not absorb stimuli, but changes its own form to become similar to aspects of stimuli that are relevant to the intent that emerged from within the brain.” (WF:27)

54Thomas Aquinas

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Nonlinear Dynamics and Thomas Aquinas

“The form of the input from the world is assimilated by the form of the AM pattern in the brain, leading from microscopic to mesoscopic scales . This process shows why the form of an input is not transferred or injected as information into the meaning structure of a brain. Instead, the brain creates an individualized pattern that is compatible with the history and goals of the organism. This is the basic cellular process of assimilation, the enactment of the unidirectional relation of the self to the world. The constructions revealed by the AM patterns result from what Aquinas called the imagination, and what I call the non-linear dynamics of neuron populations, and they relate to the meanings of the stimuli, not the unique and evanescent details of each

injection of sensory input.”

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Philosophy of Neuroscienceaccording to Freeman

• Materialist View

• Cognitivist View

• Pragmatist View

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Neurodynamics

A possible area of application taken from psychology:

Association psychology

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Association Psychology

“A discourse can develop in two different directions: The subject of the discourse can change into another subject by way of the similarity operation or the contiguity operation. The first operation could be called the metaphorical, the second the metonymical mode.”

R. Jakobson and M. Halle, Fundamentals of Language, 1971

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Attractor Dynamics in Associations

Association Operation Language Freud Area ?

similarity metaphorical paradigma symbolization

identification

contiguity metonymical syntagma condensation

displacement

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Free Will

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Henrik Walter‘s Criteria for Freedom of the Will

A person P has a free will just in case

• P has the capability to act differently

• P can give intelligible reasons for his/her actions

• P is the causal originator of his/her actions

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Action in the Causal Chain Picture

Originator of Action

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Conclusion

Given the picture of linear causality, there is indeed no room for the originator of action. So under this premise Kim is right, and there is no escape. Therefore:

We have to give up linear causality if we want to understand mental processes, mental causation, and free will. Neurodynamics and an altered concept of causality coming with it is a way to reconstruct the intuitive notion of free will and yet staying within a determistic framework.

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Downward Causation in Shakespeare

Hamlet, III.3

King:I like him not; nor stands it safe with usTo let his madness range. ...The terms of our estate may not endureHazard so near us as doth hourly grow Out of his brows.

=>

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Guildenstern:Most holy and religious fear it is To keep those many many bodies safeThat live and feed upon your majesty.Rosencrantz:The single and peculiar life is bound With all the strength and armour of the mind To keep itself from noyance; but much moreThat spirit upon whose weal depends and restsThe lives of many. The cess of majesty Dies not alone, but like a gulf doth drawWhat’s near it with it; or ‘tis a massy wheelFixed on the summit of the highest mount,To whose huge spokes ten thousand lesser thingsAre mortised and adjoined; which when it fallsEach small annexment, petty consequence,Attends the boisterous ruin. Never aloneDid the king sigh, but with a general groan.