Elaborating functional decompositions in mechanistic explanations

1. Elaborating functional decompositions in mechanistic explanations Dingmar van Eck, 09-11 September 2009, Canterbury, UK

2. Outline • Analysis: the concept of role function in mechanistic explanations • Challenges: - inter-level integration mechanistic explanations - specifying several role functions of a single entity simultaneously • Solution: “engineering style” functional decompositions of role functions

3. Background: refining Cummins’ concept of function • Organization underspecified • Details mechanistic organization: isolated and contextual descriptions of X’s φ-ing • Cummins concept of function ambiguous: capacity described in isolation vs. contextual role

4. Role functions and context Isolated description of a φ-ing of an X Role function description of a φ-ing of an X “Expelling blood” “Contracting” “Pumping blood” “Distributing oxygen and nutrients”

5. Inter-level integration: descriptive perspectives on X’s φ-ing Ψ +1: X’s φ-ing,Contextual 0: X’s φ-ing,Isolated -1: P’sρ-ing, Constitutive

6. Inter-level separation • Explanations in neuroscience: multi-level nested mechanistic explanations • Nested explanations: relate contributions of organizedactivities at lower and higher mechanistic levels  relate role function descriptions • Isolated descriptions: not organized, hence not part of mechanistic explanations  disconnect relationship between ρ-ing Ps, φ-ing Xs, Ψ-ing Ss

7. Inter-level separation Ψ Isolated description not part of mechanism for S’s Ψ-ing  -1 mechanistic explanation disconnected from +1 mechanistic explanation

8. Describing several role functions of a single entity simultaneously • Role function descriptions “contextual to degrees”: • E.g., In different contexts role function of contracting described as expelling blood, pumping blood, or oxygen and nutrients distribution • Organization concept unfit to describe role functions (and their relationships) of a single entity concurrently: • Contribution/role refers to other entities and activities • no (hierarchical) functional organization • Nesting mechanistic explanations as a possible solution  drawback: not role functions of the same X’s φ-ing anymore

9. Engineering style functional decompositions • Sub functions hierarchically and temporally ordered by their functional input and/or output • Ordering defines a functional organization: • Capturing contribution sub function to other sub function(s) and to overall function

10. Engineering functional decompositions Functional decomposition power screwdriver

11. Functional decomposition of “pumping blood” Pumping blood Import blood Transport blood Expel blood Relax Contract

12. Elaborating a functional decomposition Pumping blood Import blood Transport blood Expel blood Relax Contract

13. Conclusions • Recasting isolated descriptions of X’s φ-ing assub functions in a functional decomposition of a role function • Specifying relationships between several role functions of a single entity simultaneously by means of functional decompositions • Benefits: • Inter-level integration • More precise descriptions and ascriptions of role functions (and their relationships)