Section 3.7
Teleology Naturalized
Questions
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5.
What is teleology?
Why are we striving to escape from it?
What are the remnants of teleology in
biology?
What are the possible explanations of
biological teleology?
How can we naturalize biological teleology?
What is teleology?
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Teleology is a form of explanation:
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Teleology explains phenomena by referring to
purposes, ends, aims, etc.
Teleology is an answer to “why?” and “what
for?” questions:
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Why do birds have wings?
Why do we have eyes?
What are cell phones for?
What is teleology?

Teleological explanations versus mechanical
explanations:
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Q: Why does rain fall?
M: Rain falls because evaporized water
condenses when temperature decreases and its
density increases. Hence, the gravitational force
over water drops exceeds ascending force of air.
T: Rain falls in order to water crops and nourish
living things.
What is teleology?

Some historical preliminaries of teleological
explanations:
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Plato: Everything was created by demiurgos. Since
demiurgos (god) created everything for a reason, everything
is at its best:
“This ordered world is of mixed birth; it is the offspring of a
union of Necessity and Intellect. Intellect prevailed over
Necessity by persuading it to direct most of the things that
come to be toward what is best, and the result of this
subjugation of Necessity to wise persuasion was the initial
formation of this universe (Timaeus, 48a trans by Zeyl).”
What is teleology?

Aristotle’s teleology:
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Like moves to like: For instance, a stone falls toward the
center of earth because they are both made up of same
essential ingredients.
Development of organisms from birth to adulthood is guided
by an intrinsic purpose. The adult organism is the purpose
of development.
Functional parts of organisms exist because of their benefits
to their possessors.
Pure chance can not explain the order we observe in
organic and inorganic worlds.
Why are we striving to escape from
teleology?

Findings of the sciences eliminated teleological
explanations from many fields of science:
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Newtonian physics explains movements of objects without
referring to purposes:
There is no purpose of a stone which falls down to earth. It
just obeys a law of nature.
Nature is not perfectly ordered. For instance, planets do not
follow circular orbits as once imagined by ancient Greeks.
Earth is not the center of the universe. Hence, the universe
is not centered around humans.
What are the remnants of teleology in
biology?
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Functions and functional explanation:
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Functional explanation is a remnant of
teleological talk because by assigning functions to
objects we answer a “what for” question.
For instance: “What is the function of DVDs?” can
be translated as “What are DVDs for?”
In the case of artifacts, there seems to be no
interesting problem. Artifacts are produced or
used for specific purposes: DVD’s are produced
and used for storing digital information.
What are the remnants of teleology in
biology?

What about biological traits?
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What is an hemoglobin molecule for? Is this
question a legitimate one? Can you sense any
problem about this question?
The problem is that hemoglobin molecules are not
designed by intelligent agents like humans.
When we say that “the function of hemoglobin
molecules is to carry oxygen to tissues” we must
be meaning something else.
What are the possible explanations of
biological teleology?

Creationist Explanation:
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An omnipotent God created all living things at once. Since
living things are products of an intelligent being, functions
they possess reflect God’s intentions.
In other words, we must analyze living things just as we
analyze artifacts. “What for?” questions are legitimate
questions.
For instance: What is hemoglobin for? can be answered by
the statement “It was designed by God to carry oxygen to
tissues.”
What are the possible explanations of
biological teleology?

What is wrong with the creationist approach?
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If we are to explain complexity and order in
nature, we should do it by using simpler means.
Even if we solve the problem of explaining natural
order, we need to explain how God achieved his
aims. The concept of God needs explanation too.
Organic world is full of imperfect adaptations.
We can observe the change in the living world
even in our lifetimes. Think of the evolution of HIV
in a few decades.
What are the possible explanations of
biological teleology?

Darwinian Explanation
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Functional traits of organisms are products of a
lengthy chain of natural events. The totality of
these natural events is called natural selection.
What is natural selection?
Organisms in a population may have different
traits: Birds have differing wing lengths, bacteria
have differing capacities of antibiotic resistance,
humans have different eye colors, etc.
Darwinian Explanation
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What is natural selection?
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Some of these differences are heritable. For
instance, resistant bacteria have resistant
offspring, tall parents have tall children, etc.
These heritable differences affect reproduction
rates of their owners. For instance, resistant
bacteria produce more offspring, tall parents
produce greater a number of children, long
winged birds have more offspring, etc.
Darwinian Explanation

What is natural selection?
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Having more offspring changes the composition
of the population in favor of fitter organisms. The
fitter trait increases in the population.
The function of a trait is the effect which helped
the trait to spread: The function of hemoglobin is
binding oxygen because binding oxygen is the
effect which caused the spread of hemoglobin
carrying organisms.
Darwinian Explanation
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Some conceptual distinctions:
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Adaptations versus adaptive traits : Adaptation refers to a
product of natural selection. A product of natural selection
may or may not have current utility. An adaptive trait is
currently beneficial to the organism.
For instance hemoglobin binds CO with a greater affinity
than it binds to oxygen. CO is a toxic agent. In some
circumstances, having hemoglobin may be detrimental to
the organism. But it is still an adaptation.
Adaptation is an historical concept, whereas adaptiveness
is not.
Darwinian Explanation
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Some conceptual distinctions:
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Ontogenetic adaptation versus phylogenetic adaptation:
Ontogenetic adaptation: Adaptive changes that occur during
the lifetime of an organism. For instance, a human infant’s
learning how to deal with physical objects is an ontogenetic
adaptation.
Phylogenetic adaptation: Adaptive changes that occur
during the genesis of a species. For instance, the growth in
brain size of primate lineage resulting in humans is a
phylogenetic adaptation process.
How can we naturalize biological
teleology?
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Etiological theories of function:
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Proponents of etiological theories claim that functional
explanations anwer the question “why is trait x present?”
Etiological theories try to demarcate accidental effects from
genuine functions. For instance, hearts make thumping
noises besides pumping blood. We don’t want to ascribe
functions to such accidental effects. But we need a ground
to distinguish functions from side-effects.
The ground for that distinction is provided by designer and
user intentions in the case of artifacts. For instance when
we ask “what is the function of that fan in my computer?” we
are asking why did the engineer put that fan in that specific
location.
How can we naturalize biological
teleology?

Etiological theories of function:
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In the case of organic functions we explain the presence of
the trait by referring to a specific effect that led to the
selection of the trait.
For instance “the function of hearts is to pump blood” can be
justified by the statement “the effect that lead to the spread
of hearts in an ancestral population was their ability to pump
blood”.
This way, we may demarcate functions from accidental
effects: Making thumping noises is not a function of hearts
because hearts are not selected for that effect.
How can we naturalize biological
teleology?

Causal-role theories of function
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Function ascriptions do not need to be historical
hypotheses.
The aim of function ascription is to analyze complex
systems into simpler parts.
Function=the contribution of simpler parts to a systemic
capacity.
For example, when we ask “what is the function of that fan
in my computer?” we are in fact asking “what contribution
does that fan make to the working of that computer”
How can we naturalize biological
teleology?

Causal-role theories of function
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Flowchart diagrams, abstract descriptions of electronic
circuits or assembly lines are best examples of this
approach. Consider the computer fan example I mentioned
before. The function of the fan is to cool the processor.
Cooling the processor is a capacity of the computer which is
achieved by the inner workings of the fan. The fan can be
decomposed into its simpler parts. These simpler parts
contribute to the cooling capacity of the fan, hence, one can
explain how the cooling capacity of the computer is realized
by means of analyzing relevant parts into simpler and
simpler capacities they have.