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Causal relations, constitutive relations, and interlevel experiments

Bert LeuridanCentre for Logic and Philosophy of Science

Ghent UniversityBert.Leuridan@UGent.Be

MaCitS 2009Canterbury

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Craver C.F. (2007), Explaining the Brain.Mechanisms and the Mosaic Unity of Neuroscience. Oxford: Clarendon Press.

CLAIM 1:Mutual manipulability is not a sufficient condition for constitutive relevance

CLAIM 2:This gives rise to further inferential challenges for (interlevel/intralevel) experimental practice(problem of underdetermination)

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Outline

1. Mechanisms

2. Intralevel causal relations

3. Interlevel constitutive relations

4. Mutual manipulability not sufficient for constitutive relevance4.1. parthood as spatial containment: virus and general4.2. causal feedback in biology4.3. measuring synchronicity4.4. causal-constitutive propagation

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1. Mechanisms

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Mechanisms• A mechanism is

a set of entities and activities organized such that they exhibit the phenomenon to be explained. (Craver 2007, 5)

• More precisely

Entities are the components or parts in mechanisms. They have properties that allow them to engage in a variety of activities. [...] Activities are the causal components in mechanisms. [...] Finally, the entities and activities in mechanisms are organized together spatially, temporally, causally, and hierarchically [...] The behavior of the mechanism as a whole requires the organization of its components [...]. (Craver 2007, 5-6)

(Carl Craver (2007) Explaining the Brain. Mechanisms and the Mosaic Unity of Neuroscience. Oxford: Clarendon Press.)

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Mechanisms

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

A phenomenon (top) and its mechanism (bottom) (from Craver 2007, p. 7)

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2. Intralevel causal relations

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Mechanisms

• Question: How should activities be characterized?

• Answer: Woodward’s manipulationist theory of causation

(Craver 2007, chapter 3)

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Intralevel causation

• Manipulationism:The central idea is that causal relationships are distinctive in that they are potentially exploitable for the purposes of manipulation and control.

More specifically, variable X is causally relevant to variable Y in conditions W if some ideal intervention of X in conditions W changes the value of Y (or the probability distribution over possible values of Y). (Craver 2007, 94)

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Ideal (etiological) interventions

X S Y

U

I C

(Craver 2007, p. 97)

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Ideal (etiological) interventions

An ideal intervention I on X with respect to Y is a change in the value of X that changes Y, if at all, only via the change in X.

More specifically, this requirement implies that:

(I1) I does not change Y directly;

(I2) I does not change the value of some causal intermediate S between X and Y except by changing the value of X;

(I3) I is not correlated with some other variable M that is a cause of Y; and

(I4) I acts as a ‘switch’ that controls the value of X irrespective of X’s other causes, U.

(Craver 2007, 96; adapted from Woodward and Hitchcock 2003a)

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Mechanisms

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

A phenomenon (top) and its mechanism (bottom) (from Craver 2007, p. 7)

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3. Interlevel constitutive relations

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Interlevel constitutive relations

• Question: how should constitutive relations be characterized?

• Answer: – Negative: constitutive relations are not causal!– Positive: constitutive relevance as mutual manipulability

Craver (2007, chapter 4)Craver & Bechtel (2007) “Top-down causation without top-down causes,” Biology and Philosophy 22: 547-563.

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Constitutive relations

Constitutive relations are not causal:1. Symmetry: All constitutive relations are

symmetric; (most) causal relations are asymmetric

2. Synchronicity: All constitutive relations are synchronic; if causes must precede their effects, causal relations are diachronic

3. Logic: mechanisms and their components are not distinct; causal relations ought to involve distict relata

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Mutual manipulability

Question: When is a part of S a component in the mechanism of S’s -ing? (Craver 2007, 140)® When is a part constitutively relevant?® Not all parts are components!

Craver: Working Account (sufficient condition)[A] component is relevant to the behavior of a mechanism as a whole when one can wiggle the behavior of the whole by wiggling the behavior of the component and one can wiggle the behavior of the component by wiggling the behavior as a whole. The two are related as part to whole and they are mutually manipulable. (Craver 2007, 153)

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Mutual manipulability

X is a component of the mechanism for S’s -ing if:

• (i) X is part of S;

• (ii) in the conditions relevant to the request for explanation there is some change to X’s -ing that changes S’s -ing; and

• (iii) in the conditions relevant to the request for explanation there is some change to S’s -ing that changes X’s -ing.

(Craver 2007, 153)

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Mutual manipulability

• (CR1) When is set to the value 1 in an ideal intervention, then takes on the value f(1). (Craver 2007, 155)– [Moreover] there should be an ideal intervention on X's -ing

that changes the value of S's -ing under the conditions (CR1a) that the intervention, I, leaves all of the other dependency relations in S’s -ing unchanged and (CR1b) that other interventions have removed the contributions of other redundant components. (Craver 2007, 156-157)

• (CR2) [I]f is set to the value 1 in an ideal intervention, then takes on the value f(1). (Craver 2007, 159)

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Ideal (interlevel) interventions

An ideal intervention I on with respect to is a change in the value of that changes , if at all, only via the change in . This implies that:

(I1c) the intervention I does not change directly;

(I2c) I does not change the value of some other variable * that changes the value of except via the change introduced into ;

(I3c) that I is not correlated with some other variable M that is causally independent of I and also a cause of ; and

(I4c) that I fixes the value of in such a way as to screen off the contribution of ’s other causes to the value of .

(Craver 2007, 154)

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Ideal (interlevel) interventions

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

I

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Ideal (interlevel) interventions

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

I

(I4C)

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Ideal (interlevel) interventions

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

I

(I4C)

M

(I3C)

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Ideal (interlevel) interventions

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

I

(I4C)

M

(I3C)

(I2C)

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Ideal (interlevel) interventions

S-ing

X11-ing

X22-ing

X33-ing

X44-ing

I

(I4C)

M

(I3C)

(I2C)

(I1C)

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4. Mutual Manipulability not sufficient

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Constitutive relevance (recap)

X is a component of the mechanism for S’s -ing if:• (i) X is part of S;

• (ii) in the conditions relevant to the request for explanation there is some ideal intervention to X’s -ing that changes S’s -ing; and

• (iii) in the conditions relevant to the request for explanation there is some ideal intervention to S’s -ing that changes X’s -ing.

Claim: is this not a sufficient condition for componency

start: when is X part of S?

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Parthood as spatio-temporal containment?

Question: when is X part of S?(NOT “when is X a component of S?”

Suggestion: when X is spatio-temporally contained in S

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Parthood as spatio-temporal containment?

The virus and the general:When a virus kills a general, this seems to be an interlevel causal interaction. [...] However, the general and the virus are not at different mechanistic levels. The virus is not a component in any of the myriad mechanisms composing the general. This is simply a case where things of different sizes interact. (Craver and Bechtel 2007, 556)

In practice: virus seems constitutively relevant• token virus spatially contained in token general• virus’s presence/absence and general’s presence/absence are mutually

manipulablevirus general : evidentgeneral virus : cf. the mass extinction of stock to suppress epidemics in agriculture

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More than a toy-example

• Virus & General: toy-example• However:– examples of causal feedback are legion in the biological,

including neuroscience, and the social sciences: mutual manipulability

– causal feedback is even considered one of the motors generating biological complexity and higher level phenomena – the very phenomena Carl Craver wants to explain (Mitchell forthcoming, 34-44).

– (Note: causal feedback in figure 1.1, Craver 2007, 7)

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Tree of problemsIF X part of S AND X and S mutually manipulable, THEN X component of S

Virus a component of the general?

Parthood as spatial containment

Solution 1:virus and general distinct

Solution 3:Relation is diachronic

Begs the question Causal-constitutive propagation

Solution 2:Distinct notion of parthood

Which?

Measuring synchronicity

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Measuring synchronicity

Causal,Time-lag

Causal,Time-lag

Causal,Time-lag

Causal,Time-lag

Even if constitutive relations are synchronic, they may look like diachronic relations in practice

Craver (2007, 146)

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Causal-constitutive propagation

• Even if constitutive relations are synchronic, they may look like diachronic relations in practice

• Bottom up:do(i=i

*) =’: constitutive, synchronic

do(i=i*) j =g(i*): causal, diachronic

j=g(i*) =’’: constitutive, synchronic

• Top down: analogously• This is not a case of redundancy/recovery! And it is

not ruled out by CR1a and CR1b

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Causal-constitutive propagationS-ing

=f(’1, ’2, ’3)

X11-ing1=’1

X22-ing2=’2

X33-ing3=’3

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Causal-constitutive propagationS-ing

=f(1*, ’2, ’3)

t

X11-ingdo(1=1*)

X22-ing2=’2

X33-ing3=’3

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Causal-constitutive propagationS-ing

=f(1*, g(*1), ’3)

t

X11-ingdo(1=1*)

X22-ing2=g(1*)

X33-ing3=’3

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Causal-constitutive propagationS-ing

=f(1*, g(*1), g’(g(1*)))

t

X11-ingdo(1=1*)

X22-ing2=g(1*)

X33-ing3=g’(g(1*))

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Causal-constitutive propagation

• An intervention on Xi’s i-ing induces, diachronically, a change in S’s -ing

• An intervention on S’s -ing induces, diachronically, a change in Xi’s i-ing

• Xi is spatially contained in S

• Is Xi a component of S?

• Or are Xi and S mutually causally related?

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Conclusion• Mechanisms involve intralevel causal relations and interlevel

constitutive relations– Both are characterized by means of ideal interventions

• Claim 1: mutual manipulability (+ parthood) not sufficient for constitutive relevance

• Claim 2: problem of underdetermination in experimental practice: suppose that– X is spatially contained in S– X and S are mutually manipulable– Question:

• is X a component of S?• or are X and S mutually causally related

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References

• Craver (2007), Explaining the Brain : Mechanisms and the Mosaic Unity of Neuroscience. Oxford: Clarendon Press.

• Craver and Bechtel (2007), “Top-down causation without top-down causes,” Biology and Philosophy 22: 547-563.

• Mitchell (forthcoming), Unsimple Truths: Science, Complexity and Policy. Chicago: University of Chicago Press.

• Woodward (2003), Making Things Happen. A Theory of Causal Explanation. Oxford: Oxford University Press.

• Woodward and Hitchcock (2003), “Explanatory Generalizations, Part I: a Counterfactual Account,” Nous, 37: 1-24.

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Argument from symmetry

• I endorse the claim that all constitutive relations are symmetric

• But some Woodward-causal relations are symmetric : – Ideal gas law– Causal feedback in biological/social sciences

• Therefore:– Argument from symmetry shows a distinction at the

conceptual level– But provides no way to distinguish between symmetric

causal relations and constitutive relations

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Argument from synchronicity

• I endorse the claim that all constitutive relations are synchronic• But some Woodward-causal relations are synchronic :

– ideal gas law? – pendulum?

• Problems:– Problem of measuring synchronicity– Problem of causal-constitutive propagation

• Therefore:– Argument from synchronicity shows a distinction at the conceptual

level– But provides no way to distinguish between synchronic causal

relations and constitutive relations

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Argument from non-distinction

• I endorse the claim that all causal relations must involve distinct relata

• Therefore:– The argument provides a way to distinguish

between causal relations and constitutive relations: if X and Y are related as part and whole, none is a cause of the other

– Problem: how do we know that X is part of Y?

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A note on etiological invariance

• If invariance under interventions is to count as a sufficient condition for causal relevance (Woodward)

• Then it should be complemented with the addendum that the relata are not related as part and whole (not currently in Woodward)

• Otherwise: constitutive relevance implies causal relevance