Teleology and functions

Teleology - life’s aspirations

It is a correct position that “true knowledge is knowledge by causes.” And causes again are not improperly distributed into four kinds: the material, the formal, the efficient, and the final. But of these the final cause rather corrupts than advances the

sciences, except such as have to do with human action. Francis Bacon, Novum Organon, aphorism 3

Ends, and domains of explanation

• Human intention and technology (techne =def “art”)– Psychological/cognitive (design)– Ethical

• Natural processes– Cosmic purpose– Physical processes (planetary orbits)– Living processes - 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)

Telos, a goal

• Telos = Greek for “goal” (fulfilment or completion, consummation, end)

• Plato: Mind is the cause for everything (External telos)

• 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 of plenitude)

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 for which it is changed)

Kant and teleology

• In the Critique of Judgement (1790) he argued that teleology was necessary to explain things that are “both cause and effect of itself”, particularly living things (§64)

• His was a natural teleology following natural laws

• Distinguished generic natural purposes from individual natural purposes

• Influenced many later biologists

Goals and purposes - where do they come from?• Traditional view:

– Goal-directed: change is targeted to attaining an outcome (an end)

– Goals come from:• External source: God (Platonic teleology)• Internal source: Inner nature (Aristotelian

entelechy)• External system <Natural Selection?>

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

The old and the new

Teleomatic, or end-

resulting

Teleonomic, or end-directed

Teleological,

or end-seeking

Teleological, or end-seeking

Teleonomic, or end-directed

Teleomatic, or end-

resulting

Cognitive

Functional

Lawlike

Idealist MechanistProcesses

Progress in evolution

• Inevitability• Net progress versus local progress• Eliminating progress• Social progress and biological

progress

Summary

• Modern teleology inverts the older kind

• Biological teleology is a by-product of adaptation

• Teleology is an explanatory strategy

Functions

What are they good for?

Why care?

“The organic world is full of functions, and biologists’ descriptions of that world abound in functional talk.” [Philip Kitcher]

• What biological things are functional?

• Are they functional in the things themselves?

• What function do functions have in explaining biological systems?

Naturalising teleological talk

• Functions used to mean “goals” or “goal-oriented behaviour”

• We want, after evolution, to see goals as natural results - evolution is not goal-directed.

• Can we speak of functions without thinking they are imposed from outside biology?

Philosophical Approaches

• Conceptual Analysis - finding out how some group uses a term. Useful for that, but tells us nothing else

• Scientific Analysis - how a scientist ought to use the term relative to a theory (e.g., evolutionary theory)

• Metaphysical Analysis - the nature of existing things, no matter how we use words or what works in a theory

Functions in biology

• Three versions1. Homeostatic (what keeps it like

that)2. Etiological (where it came from)3. Propensity (what it will do in future)And one compound version: the

Relational account (1 + 2).• Vestiges - what is a vestige?

Homeostatic functions

• AKA Causal Role or Systems-analysis functions. Var: Cummins functions, or Homeostatic Property Clusters

• “Homeostasis” = “keeping the same”• Something is functional iff it

contributes to the homeostatic maintenance of the organism or system of which the function-bearing trait is a component. [def]

Problems with Homeostatic functions

• Seems to require a prior knowledge (that it is interesting and needs explaining, e.g., the heart), or

• Assigns functions to uninteresting things (the function of clouds in the rain cycle)

• Hence needs an etiological account to restrict it to interesting biological functions

Etiological functions

• AKA Selective Effect functions. Var: Wright functions, or proper functions

• “Etiology” = account of the causal origin• Something is functional iff the appearance and

maintenance of that trait in the lineage of which the organism is a member is due to past contributions to the fitness of that lineage [def]

Problems with Etiological functions

• Not required to do a functional analysis (Harvey on the heart)

• Relies on knowledge or knowability of the evolutionary history of the trait

• Involves using a problematic concept - homology• What is the “proper” function of things? (Acorns

and squirrels): “Normal” versus “normal”

Propensity account

• Something is functional iff it has a propensity to contribute to the future fitness or survival of the lineage or organism [def]

• How do we know what something will encounter in the future?

• Mystery definition: “fitness” in the future

Modern History Account, and Vestiges

• Something is a function if it has been selected for in the recent past.

• Things can be retained for a while even if no selection in their favour (adaptation versus adapted distinction)

• Something can have had a function, but now doesn’t - a vestige

• Deselected for old function, newly selected for new function

Selection for function

• Function can persist when selection is relaxed

• Traits no longer adaptive are vestiges (Sober: were adaptations, are now not adaptive)

Selection for function

• Vestiges for one trait (A) can be co-opted as functions for another trait (B)

Normality Problem

• Something is a function when?• Is the function of acorns to reproduce

oaks, or feed squirrels?

• “Proper functions” - Millikan’s etiological account. Normal ≠ average or modal. Then what?

• Normal for the clade or species? Or homeostasis of that organism? Millikan - etiology

Relational Account

• Combination of etiology (E-functions) and homeostasis (C-functions)

• Trait X’s function in organism O is F in selective regime S iff having X is S increased O’s fitness in S. A C-function increases fitness in S to the extent that it maintains O until it can breed. [def]

• “Normal” is thus dependent on reproduction

Conclusion

• We can be pluralists and think there are at least 2 functions - E-functions and C-functions and they have different roles in explanations

• Or we can be monists and think that we can combine E- and C-functions

John’s view

• We may not have naturalised functions but we can speak of explanations as being good or bad representations of biology

• Functions are something that appears in an explanation, not in the biology itself. The question is: is it a good explanation? If it is, then it is a good function.