Transcript Chapter 2 PowerPoint

Theoretical Issues in Psychology
Philosophy of Science
and
Philosophy of Mind
for
Psychologists
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Chapter 2
Kinds of explanations
• 3 kinds of explanations
• Reduction
• Levels of explanation
• Reasons and causes
• Explanatory pluralism
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Explanation
Explanation is answering to a ‘why’ question.
Three kinds of explanations:
1) Nomological explanation (D-N model) answers
‘why’ by subsumption under a general law (‘covering
law’):
• sciences.
2) Hermeneutic understanding (‘Verstehen’) answers
‘why’ by reconstructing context, explicating meaning
and experience:
• humanities.
3) Functional explanation answers ‘why’ by finding
the function (‘what is it for’); mechanistic explanation:
• biology (engineering); biological psychology.
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Nomological explanation
law 1…………law n
condition 1… condition n
explanans
event (fact)
explanandum
• Subsuming an event (fact) under a general law.
• Or deducing an explanandum from an explanans.
• Prediction logically equals explanation.
Problem: doesn’t work for motives, reasons and actions.
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Nomological explanation
Example:
L1: Frustration causes aggression
L2: Football supporters whose club lost are
frustrated
C1: These supporters’ football club lost
---------------------------------------------------------E: These football supporters are aggressive
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Hermeneutic understanding
• Understanding and explicating human behavior
and texts.
• Describing meaningful relations in context.
• Interpreting individual cases (no laws).
• Motives and reasons (not causes).
• Actions (not movements).
• Hermeneutic circle of whole and parts.
Problem: no objectivity, not verifiable or falsifiable
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Explaining
Understanding
• Natural sc.
• Social sc./humanities
• Time-spatial events
• Causes
• Nomothetical
• Object / objectivism
• Method-oriented
• Generalising over
objective facts
Experimental,
biological psychology
• Actions
• Reasons (motives)
• Idiographical
• Subject / subjectivism
• Meaning-oriented
• Unique events
• Persons experience
Client-centered therapy,
psychoanalysis
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Reasons and causes in social science
• Explaining or understanding behavior?
• Action (rational, goal-directed, meaningful,motivated).
Or
• Movement (mechanical, causal, determined).
• Solution: multiple levels of explanation, understanding
and causal explanation can coexist.
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Functional explanations
•
•
•
What an item does, what goal it serves; not what it
is (made of).
Teleology (goal-directedness).
The presence of a trait is explained by its function,
e.g., mammals have a heart to pump blood.
•
Characteristic for biology: adaptive functions
selected in evolution.
•
Evolutionary psychology: function of jealousy,
cheater detection, etc. (see Ch. 9.2).
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Functional explanations
•
•
•
The presence of a trait is explained by its
function.
Adaptation (not physical causation, not
interpretation of meaning).
How system works, its design and
functioning (no laws, no causes, no
predictions).
Problem: danger of cheap, circular, pseudoexplanation (adaptationism).
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Mechanistic explanation
•
•
•
•
Extension of functional explanation.
A phenomenon is explained by the
orchestrated functioning of the
component parts of a mechanism.
E.g., heart (mechanism) pumping blood
(phenomenon) by muscles and valves
(components) together.
Interlevel: lower level of components
explains higher level phenomenon.
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Function
•
Etiological: the trait is selected in the past
for a specific effect:
 evolutionary explanation.
•
Causal role: the contribution a trait makes
to the capacity of the whole system:
 systemic, engineering explanation.
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Functionalism
Is a materialistic notion of mind
Behaviorism:
no mental terms and
things; only
observables.
Mind-brain Identity theory:
mind is brain; mental
terms have to be reduced
to brain terms.
Functionalism:
materialism without
reductionism.
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Functionalism
•
A mental process is a functional organisation of a
machine (e.g., brain), an ‘abstract’ organisation,
can be realised in different kinds of hardware.
•
‘Token materialism’: every function is realised in
something material.
•
No ‘type materialism’: realisation in different
kinds of material objects (computers, brains).
•
Therefore no reduction to neurophysiology.
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Materialism in history
1913 – ca1950
Behaviorism (behavior)
ca 1950
Identity theory (mind=brain)
1950 – 1985
Functionalism: ‘1st cognitive
Revolution’ (cognition)
1985 – present
‘2nd cognitive revolution’
(cognition, brain & behavior)
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Two forms of mind materialism
Type materialism of
the Identity theory:
‘I’m afraid when typical brain cells
are firing’
Token materialism of functionalism:
‘I’m afraid when my cognitive system is in a
certain functional state’
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Type and token
The tokens:
student A
student B
The type, the class:
students
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Problems of type materialism (IT)
according to functionalists
• We have insufficient knowledge of brains.
• Autonomy of psychology, no reduction
(identity) of psychological to neural
processes.
• IT is too ‘chauvinistic’: only human brains
can show intelligence; but how about a
chess computer?
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Functionalism
•
•
•
•
•
Mental states are functional states of
physical systems.
Functions have a causal role (cause other
mental states and behavior).
Functions are materially though multiply
realised.
Implementation is irrelevant for explanation.
Liberalism: computers, animals, aliens can
show intelligence.
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Criticism of biologically-oriented
Functionalists
•
This is machine functionalism: function is
stripped of goal-directedness and
adaptation.
•
Therefore: teleological functionalism;
biological functions, not abstracted from
implementation or environment.
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Reduction and reductionism
Reduction: explanatory strategy
Explain complex phenomena by reducing to elements;
chain of ‘why’ and ‘because’ going down from everyday
macro-objects to elementary particles.
Reductionism: ideology
Reality is nothing but matter in motion (‘nothing buttery’),
e.g., pain is firing of certain neurons;
e.g., altruism is nothing but the blind instinct,
programmed by a selfish gene.
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Theory reduction
Theory reduction: deducing a higher level theory from
more basic theories plus bridge laws (extension of D-N
explanation):
e.g., deduce thermodynamics (temperature and
pressure) from statistical mechanics (molecules).
Bridge laws connect theories, identifying terms (things)
across theories (e.g., temperature is average kinetic energy
of gas molecules):
e.g., associative learning deduced from synaptic
potentiation; Long Term and Short Term Memory
deduced from LTP (biochemistry); ‘neural alphabet’
(Kandel).
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Classical reduction
• Deducing higher level science from lower level;
requires connectability (bridge laws) and deducibility
sociology  psychology  neurofysiology  physics
complex  simple.
• ‘Unified science’ (positivism): same kind of
observations, same kind of explanations everywhere in
science, ultimately ‘ideal physics’.
• Basic theory incorporates higher level theory
e.g., Mendelian genetics subsumed under biochemistry
(DNA).
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Classical reduction
Deducing higher level science from lower level,
connected by bridge laws; smooth incorporation of
reduced (old) in reducing (new) theory.
Problem: Old theory usually false, concepts do not refer.
New theory corrects old, meaning of concepts changes.
Therefore, no bridge laws, no deduction.
Classical reduction fails as account of real scientific
progress works.
Then:
• eliminativism: drop old theory (and its world view);
• or functionalism: non-reductive materialism, autonomy.
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Non-reductive materialism
Multiple realisation: classical reduction impossible in
neuro-psychology: no bridge laws (type identities) between
mind and brain.
Supervenience: Mental processes determined by
(dependent on) material processes. No change in mental
states without change in neural process (i.e., no disembodied
mind).
Compatible with functionalism as theory about the mind:
• autonomy for psychology, no reduction;
• but also materialism, no dualism.
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Supervenience: the mental and the neural
mental
mental
no reduction
neural1 neural2 neural3
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neural
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Reduction vs elimination
Reduction: identification of higher level phenomenon with
lower level.
Retains ontology: the reduced phenomenon really exists
e.g., water is H2O; temperature is kinetic energy;
e.g., pain is (identical with) firing of certain neurons.
Problem: old theory false, meaning changes: no bridge
laws, no reduction.
Eliminativism: replacing higher level entities and theories
by more fundamental ones.
Replaces ontology: higher level entities do not really exist
e.g., talk of neural processes replaces ‘pain’,
‘consciousness’, ‘meaning’ etc.
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New wave reductionism, eliminativism
• Responds to failure of classical reduction: higher level
eliminated.
• Old reduced theory is to some degree false, obsolete, or
incomplete.
• Old reduced theory to some degree corrected or even
entirely replaced by lower level reducing theory.
• Functional, psychological theories only approximate,
coarse descriptions.
• Cognitive phenomena can better be explained by
neuroscience.
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Reduction vs levels
• Reduction in D-N-model: unification, psychology is
neuroscience.
• Eliminativism: psychology replaced by neuroscience:
• these are one-level stories.
• Alternative: multiple levels of explanation:
• explanatory pluralism, co-evolution of theories at
different levels.
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When classical reduction fails
1. Autonomy (functionalism), or
2. Elimination (more or less correction of the
reduced theory), or
3. Explanatory pluralism (McCauley)
coexisting theories, mutually influencing
each other top-down and bottom-up.
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Explanatory pluralism
• Multiple levels of explanation coexist and
coevolve.
• No autonomous levels (unlike functionalism),
but mutual selection pressure.
• No reduction or elimination.
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