p160 antirealismclassroomversion

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Goal of science:develop good

theories of the world.

Goal of science:develop good

theories of the world.

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Goal of science:develop good

theories of the world.

Goal of science:develop good

theories of the world.What makes a theory good?

What makes a theory good?

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Science aims for literally true

theories.

Science aims for literally true

theories.

Science aims for empirically adequate

theories.

Science aims for empirically adequate

theories.

Scientific Realism:Scientific Realism:

Scientific Antirealism:

Scientific Antirealism:

Realism vs. AntirealismRealism vs. Antirealism

Empirically adequate = Empirically adequate =

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Making true claims about all the observables

Making true claims about all the observables

(but claims about unobservables might

be false)

(but claims about unobservables might

be false)

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Is an aim of science literally true theories?

Is an aim of science literally true theories?

Grover Maxwell: YES!

Grover Maxwell: YES!

(Jones’ theory of disease)

(Jones’ theory of disease)

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Disease spread by:• bodily contact with sick person• contact with items handled by sick person

Disease spread by:• bodily contact with sick person• contact with items handled by sick person

Observations:Observations:

Another phenomenon with same pattern of spread: LICE

Another phenomenon with same pattern of spread: LICE

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Disease spread by “crobes” transmitted in the same ways lice

are transmitted.

Disease spread by “crobes” transmitted in the same ways lice

are transmitted.• Crobes too small to be seen.

• Halt spread of disease by halting spread of crobes.

• Crobes too small to be seen.

• Halt spread of disease by halting spread of crobes.

Jones’ conjectureJones’ conjecture

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• Predicts who will get sick.• Predicts who will get sick.• Suggests ways to stop spread of disease (“disinfection”).

• Suggests ways to stop spread of disease (“disinfection”).

Theory works!Theory works!

Should we believe in crobes?Should we believe in crobes?

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Maxwell: No principled line we could draw between

observable and theoretical entities.

Maxwell: No principled line we could draw between

observable and theoretical entities.Nothing disreputable about

crobes!

Nothing disreputable about

crobes!

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NOT a problem of observable vs.

theoretical entities.

NOT a problem of observable vs.

theoretical entities.

Problems with MaxwellProblems with Maxwell

Rather, observable vs. unobservable.

Rather, observable vs. unobservable.

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Rather, no data to determine whether they exist or not.

Rather, no data to determine whether they exist or not.

Antirealist doesn’t need to say

unobservable entities don’t exist.

Antirealist doesn’t need to say

unobservable entities don’t exist.

Problems with MaxwellProblems with Maxwell

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Argument from success of theory to

existence of crobes is logically flawed!

Argument from success of theory to

existence of crobes is logically flawed!

Problems with MaxwellProblems with Maxwell

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So, crobes exist!

So, crobes exist!

1. If there are crobes, and if crobes cause disease, then taking steps X to stop their

spread will reduce the incidence of disease.

1. If there are crobes, and if crobes cause disease, then taking steps X to stop their

spread will reduce the incidence of disease.2. Taking steps X is

followed by a reduction in the incidence of

disease.

2. Taking steps X is followed by a reduction

in the incidence of disease.

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So, my battery is dead.

So, my battery is dead.

1. If my battery is dead, then my car

won’t start.

1. If my battery is dead, then my car

won’t start.2. My car won’t

start.2. My car won’t

start.

Bad logic! (“Affirming the consequent”)

Bad logic! (“Affirming the consequent”)

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Can only get empirical evidence about

observables, not unobservables.

Can only get empirical evidence about

observables, not unobservables.

van Fraassen’s antirealism:Constructive empiricism

van Fraassen’s antirealism:Constructive empiricism

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van Fraassen’s antirealism:Constructive empiricism

van Fraassen’s antirealism:Constructive empiricismIf I accept a theory, I

believe the claims it makes about

observables are true.

If I accept a theory, I believe the claims it

makes about observables are true.Claims theory makes about unobservables

could be false.

Claims theory makes about unobservables

could be false.

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Detectable with unaided

senses.

Detectable with unaided

senses.

Observable:

Observable:

• some observables may not have been observed.• some things would be observable if they existed.

• some observables may not have been observed.• some things would be observable if they existed.

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Not detectable with unaided

senses.

Not detectable with unaided

senses.

Why aren’t crobes

observable?

Why aren’t crobes

observable?

What you see: consequences of arrangement of

instrument + sample

What you see: consequences of arrangement of

instrument + sample

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Duhem:Observations with

instruments assume theory of the

measuring device

Duhem:Observations with

instruments assume theory of the

measuring devicearrangement of instrument +

sample

arrangement of instrument +

sample

observables

(seen through

lens)

observables

(seen through

lens)

unobservables (causing what

is seen)

unobservables (causing what

is seen)

??

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Accepting a theory

Accepting a theoryRealist:

I believe all the claims the theory makes are true.Antirealist:I believe the claims the theory makes makes about observables are true.

Realist:I believe all the claims the theory makes are true.Antirealist:I believe the claims the theory makes makes about observables are true.

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Hacking’s middle position:

Hacking’s middle position:

“Entity Realism”: I believe all the entities the theory identifies really exist,

but some of the claims the theory makes about them may be false.

“Entity Realism”: I believe all the entities the theory identifies really exist,

but some of the claims the theory makes about them may be false.

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Hacking:Microscopes tell us

something is there, but may not show us just

what that something is like.

Hacking:Microscopes tell us

something is there, but may not show us just

what that something is like.

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What a microscope gives:

Map of the interaction between

specimen and imaging radiation.

What a microscope gives:

Map of the interaction between

specimen and imaging radiation.

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Features vs. artefacts:Features vs. artefacts:Features observed from sample using different types of radiation

Features observed from sample using different types of radiation due to real

features of sample

due to real features of sampleFeatures observed from one

type of radiation different using many different samples

Features observed from one type of radiation different using many different samples due to

instrumentdue to instrument

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Entity Realism: Entity Realism: We can believe that what we see with the microscope is caused by really existing entities.

We can believe that what we see with the microscope is caused by really existing entities.Why? Because we can manipulate those entities!Why? Because we can manipulate those entities!

Chiharas’ mitesChiharas’ mites

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Hard-core antirealist:Hard-core antirealist:• Claims the mites

exists (they’re observable).• Can’t know whether the mites have legs or not!• Can’t explain changes in movement in terms of leg-removal!

• Claims the mites exists (they’re observable).• Can’t know whether the mites have legs or not!• Can’t explain changes in movement in terms of leg-removal!

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What counts as a good explanation

anyway?

What counts as a good explanation

anyway?

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