Scientific Realism
Van Fraassen’s Critique of Scientific Realism
Overview
I.
Defining
Scientific Realism
II.
Constructive Empiricism
III.
Defending the
Theory-Observation ‘Dichotomy’
IV.
Critiquing
Inference to the Best Explanation (IBE)
Defining
Scientific Realism
What
realism is not
Realism
defined
Constructive
Empiricism
Two
(overlapping) possibilities:
•
Science aims to be true, but only once properly (but not literally)
construed.
•
The language
of science should be literally construed, but its theories need not be true to
be good.
Two
antirealisms
Differences
between the two antirealisms
Option
1 (non-literal construals of theories): the quark
theory doesn’t really say
that quarks exist.
Rather statements like “Quarks exist” are useful “fictions” for
theory construction, instruments for organizing data,
making predictions and, generally soving set of problmes.
CE:
the quark theory says that quarks exist, but it would still be a good theory
even if quarks didn’t exist.
Constructive
Empiricism
On this view, science aims to give us theories which are empirically
adequate.
Acceptance of a theory involves as belief only that it is
empirically adequate. If we a
comfortable redefining “true” as to meaning nothing other that
“empirically adequate, then theories are or are not “true.” But this is clearly far afield from the old
(dare I say “quaint”) notion that scientific theories correspond to mind
independent realties or “the way the world really is.”
(Think of the uncommitted “past life regressionist therapist.)
Contrast with realism: Science aims to give us, in its theories, a literally
true story of what the world is like; and acceptance of a scientific
theory involves the belief that it is true.
Empirical
Adequacy vs. Truth
The
quark model would be false but empirically adequate if quarks “didn’t exist,” but everything it
said about observable things and events is true.
The challenge
But the CE theorist tunrs the tables on the SR:
What does “quarks exist” MEAN apart from “Quarks figuring prominently on
our most empirically adequate theories?”
“Saving the phenomena”
Applies
to future observations, unobserved but observable entities—in short, an
empirically adequate theory must save all phenomena.
Acceptance,
commitment, and belief
Acceptance
= pro-attitude toward a theory, consists of:
•
Belief = pro-attitude that statements in the theory are true;
•Commitment = pro-attitude to “confront any future
phenomena by means of the conceptual resources of the theory” (1069); more pragmatic than belief
•How
this bears on realism and CE
Both realism and CE demand that acceptance entails the belief that a
theory is empirically adequate
But realism demand “more,” also demands belief that the theory is true.
This accounts for the value of explaining phenomena by appeal to unobservables.
In place of this, CE claims that acceptance involves commitment.
As a result, the value of explanation is mostly pragmatic.
BvF
& the Theory-Observation Dichotomy
Van Fraassen replies to two potential objections to CE:
Mediation Objection: If
electron microscopes don’t yield direct observation, then neither does anything else.
Mutation Objection: “Unobservability in
principle” = “Observability under different circumstances”
BvF’s reply to the Mediation
Objection
“Granted that we cannot
answer this question [about how to classify observable and unobservable things]
without arbitrariness, what follows? That ‘observable’ is a vague predicate.’ (1073)
There
are no problems with vague predicates so long as there are clear cases of ‘observables’ and clear cases of ‘unobservables.’
A
clear case of an observable is anything seen with the unaided eye
A
clear case of an unobservable is a subatomic particle in a cloud chamber
So the
concept of unobservability, and hence antirealism, is intelligible.
Maxwell’s
“Mutation Objection”
The
theory approach to unobservability: A theoretical entity is unobservable in
principle if the theory positing it entails that it is unobservable.
Maxwell:
If we had different perceptual capacities, any entity that is unobservable in
this sense can be made observable. So there is no
difference between “unobservable in principle” and “observable under different conditions than our own.”
BvF’s reply to the Mutation
Objection (1074-1075)
This
is just punning on any concept involving “-able,” i.e., dealing with
possibility.
Ex. Is the Empire State Building “portable” because future architects
could be much more ingenious than we are?
The
proper frame of reference is with respect to what is observable by us,
our limitations as human beings.
Inference
to the Best Explanation (IBE)
Reminders
The
Ordinary Practice Argument
Smart’s First Argument
Smart’s Second Argument
Sellars’ Thought Experiment
The
Ultimate/No Miracle Argument
What
is IBE?
A
pattern of reasoning of the following form:
P
Q best explains P.
Therefore
Q.
Example:
I hear scratching in the wall; my
cheese disappears.
The best explanation of the scratching
and the missing cheese is that a mouse is in the house.
Therefore:
A mouse is in the house.
The Ordinary Practice Argument
BvF’s Rebuttal to the Ordinary
Practice Argument
“we are always willing to believe that the
theory which best explains the evidence, is empirically adequate.”
Smart’s First Argument
BvF’s Reply to Smart’s 1st Argument
Smart’s 2nd Argument (1078-1079)
BvF’s
Reply to Smart’s 2nd Argument
Sellars’ Thought Experiment (1079-1082)
BvF vs.
Sellars
The Ultimate/Miracle Argument
Theories are empirically adequate.
The
truth of theories best explains their empirical adequacy.
Therefore,
theories are true.
Van Fraassen’s Rebuttal to the Miracle Argument
Recap
Scientific
realism is the view that scientific
theories aim for truth, and acceptance involves the belief that it is true.
Constructive
empiricism is the view that theories aim for empirical adequacy, and acceptance
involves belief in empirical adequacy + commitment
There
are two kinds of argument for scientific realism:
The critique of the theory-observation
distinction
The use of IBE
Each
argument for scientific realism can be challenged.