Mechanisms, Sciences

1. Mechanisms in the Sciences:
A Gentle Introduction
Federica Russo
Dipartimento di Studi Umanistici, Università di Ferrara

2. Overview
The received view and a possible consensus
The rise of mechanisms in phil sci
The mechanism debate in the sciences
Mechanisms and …
Explanation
Functions
Causal assessment
Evidence
Practical use: mechanisms and the evidence hierarchy
2

3. THE RECEIVED VIEW
3

4. Machamer, Darden and Craver:
‘Mechanisms are entities and activities organized such that they are
productive of regular changes from start or set-up to finish or
termination conditions.’ (Machamer, Darden and Craver 2000 p3.)
Glennan:
‘A mechanism for a behavior is a complex system that produces that
behavior by the interaction of a number of parts, where the
interactions between parts can be characterized by direct, invariant,
change-relating generalizations.’ (Glennan 2002b pS344.)
Bechtel and Abrahamsen:
‘A mechanism is a structure performing a function in virtue of its
component parts, component operations, and their organization.
The orchestrated functioning of the mechanism is responsible for
one or more phenomena.’ (Bechtel and Abrahamsen 2005 p423.)
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5. A POSSIBLE CONSENSUS
5

6. Illari & Williamson:
A mechanism for a phenomenon is composed of entities
and activities organized so that they are responsible for the
phenomenon.
Illari & Williamson give up on:
Regularity
Start up, finishing conditions
Complex system
Mechanistic explanation:
Identification of the phenomenon
Identification of entities and activities involved
Identification of the organisation
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7. WHY MECHANISMS?
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8. Physical (causal) connections
Process theories of causality
Salmon-Dowe approach
A development of Russell-Reichenbach
(world-lines, at-at theory)
Salmon: ‘put the cause into because’
The because is given by the physical, causal process
(Ontic explanation)
8

9. Processes in biology?
MDC (2000, p. 7):
Although we acknowledge the possibility that Salmon’s
analysis may be all there is to certain fundamental types
of interactions in physics, his analysis is silent as to the
character of the productivity in the activities investigated
by many other sciences. Mere talk of transmission of a
mark or exchange of a conserved quantity does
not exhaust what these scientists know about
productive activities and about how activities effect
regular changes in mechanisms.
9

10. Processes in social science?
Russo (2009, p.26):
The need to look directly at social scientists’ work was motivated by a
possible difference between causal claims that involve reasonably clear
causal mechanisms and causal claims that do not. I went through five case
studies, and it turned out that none of them contains concepts typical of
aleatory causality in order to get an understanding of causal relations—to
borrow Salmon’s terminology again. Instead, statistical causality is
definitively preferred. However, to prefer statistical causality does not ipso
facto rule out mechanisms from the causal talk. […] the question is not
whether or not we aim at identifying causal mechanisms, rather, how do
we come to identify them. Causal mechanisms are not identified
through causal processes and interactions, but, according to the
social scientists’ practice, they are statistically modelled.
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11. MECHANISMS IN THE SCIENCES
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12. Biology and neuroscience
Bechtel, Craver, Darden, MDC, …
Functional individuation
Mechanistic explanation
Decomposition / re-composition
…
12

13. Social science
Analytical sociologists, Little, Russo (&
Mouchart, Wunsch), …
Mechanisms and
Methodological individualism
Statistical modelling
Social regularities
Human action
Social ontology
…
13

14. MECHANISMS AND EXPLANATION
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15. Explanation
Ontic and epistemic mechanistic explanations
Craver, Bechtel (biology / neuroscience)
Illari: ‘reconciliation’ of the ontic and epistemic
Explain … how?
Organisation, recursive decomposition
Backwards, downwards, or upwards
15

16. Aetiological (mechanistic)
explanation in social science
Structural-modelling explanations
16

17. Self-rated health in the Baltic countries 1994-1999
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18. What are the causes of self-rated
health in the Baltic countries in
the ‘90s?
X Y
Joint probability distribution
P(Ed, Soc, Phy, Loc, Psy, Alc, Self)
Recursive decomposition:
P(Self|Alc, Psy, Loc, Phy)
P(Alc|Ed, Psy, Phy)
P(Psy|Loc, Soc, Phy)
P(Loc|Ed)
P(Phy) P(Soc) P(Ed) 18

19. Here, explanation is
mechanistic explanation
epistemic rather than ontic
Mechanistic explanation is successful insofar as it
spells out the functioning of the mechanism
Spelling out the functioning of the mechanism
means identifying the causes, their actions, and
their effects

20. MECHANISMS AND FUNCTIONS

21. Functional architectures and
social structures
1. Observe properties of a
social system
2. Infer the functional
structure
3. Work out the causal
mechanism (based on 2)
4. Confirm 2 based on 3

22. 22

23. Functions and functions
The role of a mechanism or of a component of a mechanism
Craver’s isolated descriptions
“But this leaves it ambiguous whether the function is the capacity, described
in isolation and simply ‘picked out’ by its contextual role, or, instead, the
contextual role by virtue of which the capacity is picked out. A complete
description of an item’s role would describe each of these . . . There is a
difference, after all, between knowing that spark plugs produce sparks and
knowing how that sparking is situated within the complex mechanisms of an
engine.” (2001)
Description of (the functioning of) a mechanism
Cummins’ role functions
“x functions as a φ (or, the function of x in s is to φ) relative to an analytical
account A of s’s capacity to ψ just in case x is capable of φing in s and A
appropriately and adequately accounts for s’s capacity to ψ by, in part,
appealing to the capacity of x to φ in s.” (1975)

24. Functions in S-M explanations
Functions are role-functions
For the mechanism and for its components
Mechanisms are described in a contextual way
Functions help build the conceptual model
They are the theoretical underpinnings of the causal
variables
A strong conceptual link between causes and functions

25. MECHANISMS AND
CAUSAL ASSESSMENT
25

26. Causal assessment
The Russo-Williamson Thesis
To establish a causal claim we typically need
evidence of mechanisms and of difference-making
An epistemological thesis about evidence for causal claims
First formulated for the health sciences,
but can be extended to other scientific contexts
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27. Arguments for RWT
Medical practice
Preamble of IARC monographs
History of medicine
Semmelweis and puerperal fever
Snow and cholera epidemic
Evidence in epidemiology
Hill’s guidelines
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28. EVIDENCE OF MECHANISMS
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29. Disambiguation
Mechanistic evidence vs
evidence of mechanisms
Difference-making evidence vs
evidence of difference-making
Evidence vs
evidence-gathering methods
Difference-making / Mechanisms
A conceptual distinction
In practice, highly intertwined
29

30. Categories of evidence of mechanism
C E
C E
1. That there is a specific
linking mechanism
2. That there is some kind of
linking mechanism or other
3. That there is no linking
mechanism
C E
30

31. What evidence of mechanism is
1. Evidence of the existence and nature of the entities and
activities of a linking mechanism, and their organization.
In vitro evidence
Animal experiments
Analogous mechanisms
Autopsy
Simulation
Even RCTs…
2. Evidence that suggests that a linking mechanism does not
or could not exist.
Well established knowledge
Energy constraints on biochemical mechanisms
Comparative studies
C E
C E
C E
31

32. Quality of evidence of mechanism
Pluses
Each independent method for
detection of entity/interaction
Each independent research group
confirming the result
More entities in the mechanism
found
More links in the mechanism
established
Analogous mechanisms known
Robust, reproducible in different
conditions
Minuses
Single method used for detection of
entity/interaction
Single research group confirming the
result
Fewer entities in the mechanism
found
Fewer links in the mechanism
established
No analogous mechanisms known
Fragile, not reproducible in slightly
varying conditions
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33. PRACTICAL (SCIENTIFIC) USE
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34. Mechanisms in the evidence hierarchy
The evidence hierarchy:
the pillar of EBM
The role of mechanisms
(from top to bottom)
‘Reinforced concrete’
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35. The analogy of reinforced concrete
Evidence: integration, not substitution
Difference making helps with masking
Mechanisms helps with confounding
Integration helps solve more problems, and better
Difference making and mechanisms help each other with
their respective weaknesses
The more integrated, the merrier
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36. TO SUM UP AND CONCLUDE
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37. Mechanisms:
a fertile field in phil sci
Mechanism debate from causation and explanation
Usefulness and interest
Not for mechanisms per se
But for mechanisms and other concepts
Mechanisms
Are embedded in modelling practices
Can help move forward methodological quarrels
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38. 38

39. Super selected bibliography
Bechtel, William (2006). Discovering Cell Mechanisms: the Creation of Modern Cell Biology. Cambridge University Press.
Bradford Hill, A. (1965). The environment and disease: association or causation? Proceedings of the Royal Society of Medicine, 58.
Clarke, B. (2011). Causality in medicine with particular reference to the viral causation of cancers. PhD thesis, Department of Science and Technology Studies,
University College London.
Craver, Carl (2001). Role functions, mechanisms and hierarchy, Philosophy of Science, 68(1).
Craver, Carl (2007). Explaining the Brain. Clarendon Press.
Cummins, Robert (1975). Functional analysis. Journal of Philosophy, 72.
Demeulenaere, Pierre (ed.) (2011). Analytical Sociology and Social Mechanisms. Cambridge University Press.
Franck R. (ed.) (2002), The explanatory power of models, Kluwer.
Glennan, Stuart (1996). Mechanisms and the nature of causation. Erkenntnis, 44, 49–71.
Illari, P. M. (2011). Mechanistic evidence: Disambiguating the Russo- Williamson thesis. International Studies in the Philosophy of Science, 25.
Illari, Phyllis (2013). Mechanistic explanation: Integrating the ontic and epistemic. Erkenntnis, 78.
llari, Phyllis McKay and Williamson, Jon (2010). Function and organization: Comparing the mechanisms of protein synthesis and natural selection. Studies in the
History and Philosophy of the Biological and Biomedical Sciences, 41.
Illari, Phyllis McKay and Williamson, Jon (2012). What is a mechanism?: Thinking about mechanisms across the sciences. European Journal of the Philosophy of
Science, 2.
Joffe, Michael (2013). The concept of causation in biology. Erkenntnis, 78.
Little, Daniel (2006). Levels of the social. In The philosophy of anthropology and sociology (ed. M. Risjord and S. Turner), pp. 343–371. Elsevier.
Machamer, Peter, Darden, Lindley, and Craver, Carl (2000). Thinking about mechasnisms. Philosophy of Science, 67.
Mouchart, Michel and Russo, Federica (2011). Causal explanation: Recursive decompositions and mechanisms. In Causality in the sciences (ed. P. M. Illari, F. Russo,
and J. Williamson). Oxford University Press.
Russo, Federica (2009). Causality and causal modelling in the social sciences. Measuring variations. Methodos Series. Springer.
Russo, Federica (2011b). Explaining causal modelling. Or, what a causal model ought to explain. In New Essays in Logic and Philosophy of Science (ed. M. D’Agostino,
G. Giorello, F. Laudisa, T. Pievani, and C. Sinigaglia). College Publications.
Russo, F. and Williamson, J. (2007). Interpreting causality in the health sciences. International Studies in the Philosophy of Science, 21(2).
Ruzzene, Attilia (2012). Meccanismi sociali nelle scienze sociali. APhEx, 5.
Salmon, W.C. (1984). Scientific Explanation and the Causal Structure of the World. Princeton University Press.
Wunsch, Guillaume, Mouchart, Michel, and Russo, Federica (2014). Functions and mechanisms in structural-modelling explanations. Journal for General Philosophy
of Science. 39