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  1. 1. Teleology and functions
  2. 2. Teleology - life’s aspirationsIt is a co rre ct po sitio n that “true kno wle dg e is kno wle dg e by cause s. ”And cause s ag ain are no t im pro pe rly distribute d into fo ur kinds: them ate rial, the fo rm al, the e fficie nt, and the final. But o f the se the finalcause ra the r co rrupts than advance s the scie nce s, e xce pt such as haveto do with hum an actio n. Francis Bacon, No vum O rg ano n, aphorism 3
  3. 3. Ends, and domains ofexplanation• Human intention and technology (te chne =def “art”)– Psychological/cognitive (design)– Ethical• Natural processes– Cosmic purpose– Physical processes (planetary orbits)– Living pro ce sse s - we are restricting ourselves to this• Naturalising goals, the modern program– To find ways in which goals can be made natural• Anthropomorphism (seeing the world as we see ourselves)
  4. 4. Telos, a goal• Te lo s = Greek for “goal” (fulfilm e nt or co m ple tio n,co nsum m atio n, e nd)• Plato: Mind is the cause for everything (Externaltelos)• Aristotle: “that for the sake of which” (Internal telos)– Four causes: material, formal, efficient, final• Christian thought: Providence– God foreordains all and designed all• The Great Chain of Being: the world must be full(principle o f ple nitude )
  5. 5. Aristotle’s finalism• Four aitia (usu. trans. “causes”, better“explanations”):– Material (that which is changed)– Efficient (that which changes matter)– Formal (that to which it is changed)– Final (that fo r which it is changed)
  6. 6. Kant and teleology• In the Critiq ue o f Judg e m e nt (1790) he argued thatteleology was necessary to explain things that are“both cause and effect of itself”, particularly livingthings (§64)• His was a natural teleology following natural laws• Distinguished g e ne ric natural purposes fromindividualnatural purposes• Influenced many later biologists
  7. 7. Goals and purposes - wheredo they come from?• Traditional view:– Goal-directed: change is targeted toattaining an outcome (an e nd)– Goals come from:• External source: God (Platonic teleology)• Internal source: Inner nature (Aristotelianentelechy)• External system <Natural Selection?>
  8. 8. Goals and purposes• Modern view (Pittendrigh/Mayr):– Goal-directed systems (teleological)• I go to the fridge [in order] to find milk– Goal-seeking systems (teleonomic)• My digestive system processes my milk– Goal-attaining systems (teleomatic)• I drop the milk due to gravity
  9. 9. The old and the newTeleomatic,or end-resultingTeleonomic,or end-directedTeleological,or end-seekingTeleological,or end-seekingTeleonomic,or end-directedTeleomatic,or end-resultingCo g nitiveFunctio nalLawlikeIdealist MechanistPro ce sse s
  10. 10. Progress in evolution• Inevitability• Net progress ve rsus local progress• Eliminating progress• Social progress and biological progress
  11. 11. Summary• Modern teleology inverts the older kind• Biological teleology is a by-product ofadaptation• Teleology is an explanatory strategy
  12. 12. FunctionsWhat are the y g o o d fo r?
  13. 13. Why care ?“The organic world is full of functions, andbiologists’ descriptions of that world aboundin functional talk.” [Philip Kitcher]• What biological things are functional?• Are they functional in the things themselves?• What function do functions have in explainingbiological systems?
  14. 14. Naturalising teleological talk• Functions used to mean “goals” or “goal-oriented behaviour”• We want, after evolution, to see goals asnatural results - evolution is not goal-directed.• Can we speak of functions without thinkingthey are imposed from outside biology?
  15. 15. Philosophical Approaches• Conceptual Analysis - finding out how somegroup uses a term. Useful for that, but tells usnothing else• Scientific Analysis - how a scientist o ug ht touse the term relative to a theory (e.g.,evolutionary theory)• Metaphysical Analysis - the nature of existingthings, no matter how we use words or whatworks in a theory
  16. 16. Functions in biology• Three versions1 . Ho m e o static (what keeps it like that)2. Etio lo g ical(where it came from)3. Pro pe nsity (what it will do in future)And one compound version: the Re latio nalaccount (1 + 2).• Vestiges - what is a vestige?
  17. 17. Homeostatic functions• AKA CausalRo le or Syste m s-analysis functions.Var: Cum m ins functions, or Ho m e o staticPro pe rty Cluste rs• “Homeostasis” = “keeping the same”• Something is functional iff it contributes to thehomeostatic maintenance of the organism orsystem of which the function-bearing trait is acomponent. [def]
  18. 18. Problems with Homeostaticfunctions• Seems to require a prior knowledge (that it isinteresting and needs explaining, e.g., theheart), or• Assigns functions to uninteresting things (thefunction of clouds in the rain cycle)• Hence needs an etiological account to restrictit to interesting biological functions
  19. 19. Etiological functions• AKA Selective Effect functions. Var: Wrightfunctions, or proper functions• “Etiology” = account of the causal origin• Something is functional iff the appearance andmaintenance of that trait in the lineage ofwhich the organism is a member is due to pastcontributions to the fitness of that lineage [def]
  20. 20. Problems with Etiologicalfunctions• Not required to do a functional analysis (Harveyon the heart)• Relies on knowledge or knowability of theevolutionary history of the trait• Involves using a problematic concept - homology• What is the “proper” function of things? (Acornsand squirrels): “Normal” versus “normal”
  21. 21. Propensity account• Something is functional iff it has apropensity to contribute to the future fitnessorsurvival of the lineage ororganism[def]• How do we know what something willencounter in the future?• Mystery definition: “fitness” in the future
  22. 22. Modern History Account, andVestiges• Something is a function if it has beenselected for in the recent past.• Things can be retained for a while even if noselection in their favour (adaptation versusadapted distinction)• Something can have had a function, but nowdoesn’t - a vestige• Deselected for old function, newly selectedfor new function
  23. 23. Selection for function• Function can persist when selection isrelaxed• Traits no longer adaptive are vestiges(Sober: were adaptatio ns , are now no tadaptive )
  24. 24. Selection for function• Vestiges for one trait (A) can be co-opted as functions for another trait (B)
  25. 25. Normality Problem• Something is a function whe n?• Is the function of acorns to reproduce oaks,or feed squirrels?• “Proper functions” - Millikan’s etiologicalaccount. Normal ≠ average or modal.Then what?• Normal for the clade or species? Orhomeostasis of that organism?Millikan - etiology
  26. 26. Relational Account• Combination of etiology (E-functions) andhomeostasis (C-functions)• Trait X’s function in organismOis F inselective regime S iff having Xis S increasedO’s fitness in S. A C-function increasesfitness in S to the extent that it maintains Ountil it can breed. [def]• “Normal” is thus dependent on reproduction
  27. 27. Conclusion• We can be pluralists and think there areat least 2 functions - E-functions and C-functions and they have different rolesin explanations• Or we can be monists and think that wecan combine E- and C-functions
  28. 28. John’s view• We may not have naturalised functions butwe can speak of explanations as being goodor bad representations of biology• Functions are something that appears in anexplanation, not in the biology itself. Thequestion is: is it a g o o d explanation? If it is,then it is a good function.