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Contingency, Constraints and the Boundaires of Explanation
A commentary on “the contingency theses”
Vivette García DeisterPhD Student
UNAM
What am I commenting on? Commentary
Of the contingency literature spurred (in part) by Beatty (1995)
In the light of Hamilton’s (2005) critiques
As a means to point to the repercussion of contingency-centeredness
For the problem of drawing the boundaries of explanation
Overview Commentary has two parts:
1. Review part of the contingency literature (using Beatty and Hamilton as book ends)
2. Suggest that the constraints literature can inform the discussion about how to draw the boundaries of explanation
Prelude: the “contingency theses”
There is a problem with drawing the boundaries of explanation by way of laws
The contingent-necessary dichotomy is misinformative about the power/depth/scope of a generalization
Contingency plays an important role in scientific explanations
There are better and worse ways of representing contingency and incorporating it in explanations
Part 1: Review of the contingency literature Beatty’s thesis, captured in his most
often-cited passage, is this: “[A]ll distinctively biological
generalizations describe evolutionarily contingent states of nature…This means that there are no laws of biology. For, whatever ‘laws’ are, they are supposed to be more than just contingently true” (Beatty 1995, p. 46).
Part 1: Review of the contingency literature Two authors address Beatty’s
concerns and conclusions in ways that are particularly informative to the problem of how to draw the boundaries of explanation: Sandra Mitchell (2003) James Woodward (2003)
Part 1: Review of the contingency literature Mitchell takes up Beatty’s verdict
about biology’s failure to produce scientific laws due to contingency
She replaces the accidental-necessary dichotomy with the contingent-stable continuum Pragmatic laws
Part 1: Review of the contingency literature Hamilton (2005) has detected a
patent difficulty in comparing degrees of stability when drawing a continuum, “since it is not clear how to compare the degree of stability of regularities in any fine-grained or principled way” (Hamilton 2005, p. 69). Problem of commensurability
Part 1: Review of the contingency literature Woodward explores the
implications that Beatty’s conclusion has for an account of explanation Move away from the nomothetic
conception of explanation “Invariance is the kind of stability that
matters”
Part 1: Review of the contingency literature Woodward’s account only applies
to mathematical representations of systems that can be manipulated and intervened upon in principle Problem of tractability
Expanded by Waters (2005) to investigative strategies in genetics
Explored by Mitchell (2005) in the context of developmental research programs
Part 1: Review of the contingency literature Notions of constraint
Beatty, Mitchell: contingency draws the boundaries of explanation by limiting constraining the attainment of laws
Nomic inhibition (Hamilton 2005) Woodward: account of explanation
should comply with epistemological constraints
Modular representation (Hamilton 2005)
Interlude: lessons learned The strategy for drawing the
boundaries of explanation is not the strategy for asessing the attainment of laws
Contingency-centeredness presents commensurability/tractability difficulties
Footnote Commensurability Qualitative
aspects of contingency (Martínez, tomorrow night)
Tractability We could benefit from a robust account of abstraction (Winther, tonight)
Part 2: taking constraints seriously Motivations for the focus on
constraints (1) Originates with a project that is
meant to limit the power of natural selection as the canonical cause of evolution
Project of drawing the boundaries of explanation by assessing causal roles, rather than nomic roles
Part 2: taking constraints seriously Motivations for the focus on
constraints (2) Literature on constraints takes
evolutionary contingency into account in a non-trivial sense according to which the origin of constraints is itself evolutionarily contingent and accounts for their taxon specificity
Part 2: taking constraints seriously Motivations for the focus on
constraints (3) For over two decades,
representatives of the constraints literature have engaged and tackled the problem of commensurability/tractability
Part 2: taking constraints seriously Identifying sources of constraint and
means to distinguish among them (e.g., Alberch 1982, Maynard-Smith et. al., 1985)
Recommending ways to establish and test constraint hypothesis (e.g., Alberch 1985, Vogl and Riensel 1991)
Developing methods for their quantitative assessment (e.g., Cheverud et. al. 1985)
Evaluating their feasibility and explanatory power (Mary McKitrick 1993)
Part 2: taking constraints seriously Ongoing debate is not merely
terminological What is the relationship between
selection and constraint? Limits of selection as cause or as
restriction of phenotypic change Causal contribution of constraints
Part 2: taking constraints seriously First strategy: conceptual
separation Constraints are seen “as manifested
in their effects on selection, implying that constraint is one thing and selection another” (Schwenk and Wagner 2003, p. 53)
Endorsed by Maynard-Smith et. al.’s (1985) notion of developmental constraints
Part 2: taking constraints seriously Developmental constraints are
“biases on the production of variant phenotypes or limitations on phenotypic variability caused by the structure, character, composition, or dynamics of the developmental system” which “undoubtedly play a significant role in evolution” (Maynard-Smith et. al. 1985, p. 265)
Part 2: taking constraints seriously Second strategy: conflation
Consists in “identifying constraint with a particular evolutionary outcome or pattern,” thus concluding that “the responsible mechanism is, by definition, ‘constraint’” (Schwenk and Wagner 2003, p. 53)
McKitrick’s (1993) notion of phylogenetic constraints endorses/emends this view
Part 2: taking constraints seriously Phylogenetic constraints are
“any result or component of the phylogenetic history of a lineage that prevents an anticipated course of evolution in that lineage” (McKitrick 1993, p. 309)
Part 2: taking constraints seriously Proponents of both the separation and
conflation approaches agree that: There is a void in the explanatory work
that selection can (should?) do and a notion of constraint is bound to occupy it
There are epistemological requirements of constraint tractability that must be met by a working definition of constraint
Part 2: taking constraints seriously Proponents of both the separation
and conflation approaches agree that:
A working definition of constraint must refer to local mechanisms (or processes) examined at a specified developmental stage and they must apply to a limited range of taxa
The acquisition of constraints is itself evolutionarily contingent
Part 2: taking constraints seriously Schwenk and Wagner´s (2003) analysis
of the separation strategy “[T]he failure to generate phenotypic
variability during development cannot be temporally or mechanistically separated from the action of selection” (p. 54)
“[A] dichotomous approach leads to a highly restrictive notion of constraint that does not satisfy the needs of many evolutionists for a constraint concept” (p. 54)
Part 2: taking constraints seriously Schwenk and Wagner´s (2003) analysis
of the conflation strategy Sympathetic towards it, provided that the
circumstances in which selection acts as a constraint are specified contextually
By establishing a set of fixed points (specifying factors) around which constraint can be organized, they propose a strategy to draw the boundaries of operation of constraint and outline its explanatory power
Preliminary conclusions Pointed to an ongoing debate in
biology where a strategy for drawing the boundaries of explanation is being sought
Debate addressed by both biologists and philosophers of biology
Preliminary conclusions Proposed strategy is not meant to
solve the commensurability/tractability difficulties of contingency
Engages and tackles these difficulties in its own domain
It does not shelve Beatty’s evolutionary contingency thesis
More coming up
If you want to know what constraints can do for the contingency literature, stick around for Sandra Mithchell’s talk, after lunch...
Acknowledgements CONACYT project 41196-H:
Filosofía de las prácticas científicas, for funding
Members of the Griesemer lab at UC Davis, for input
Sergio Martínez and Andrew Hamilton, for discussion
You, for attending this session