Scientific Realism

OHear: Chap. 6

Positivism

Emphasis on verification or falsification: testability

an informative statement or theory should make an observable difference

i.e., it should be compatible with certain possible observations
and incompatible with others

things that don't pass muster

religious doctrines, political ideologies, ethical codes: Heaven discovered!
metaphysical principles: important in the history of science, but untestable

materialism: everything is made of matter
atomism: matter is made of tiny indivisible particles
mechanism: no action at a distance
determinism: every event has a cause

guiding metaphysical principles may be accorded a heuristic role in the context of discovery

All genuine knowledge is base on sensory experience: Empiricism

on the deliverances of our five senses
not revelation or not the unaided power of reason
verification and falsification mean perceptual verification and falsification

Humean slant on causation

only correlation or "constant conjunction" can be verified
the supposed necessary connection is unobservable and untestable

Anti-Essentialism

no distinction between

accidents: features that happen to go together: Humans have appendices.
essences: features that supposedly have to go together: Humans have brains.

all regularities are equal except for "quantitative differences" such as differences

for their constancy: some more regular than others
and their coverage

Hostility to unobservable theoretical entities.

CON: Hasn't the postulation of such entities played a major role in scientific progress?

from genes (which were unobservable) to (unobservable) DNA
from atoms to their parts (electrons, protons, & neutrons) to their parts (leptons? quarks?)

CON: Aren't today's unobservables tommorow's observables?

It seems there's no sharp discinction between observable and theoretical
So, why have a cow about it?

PRO: Aren't some things inherently unobservable?

van Frassen's candidates: space-time, fields, elementary particles, alternative possible states of affairs
the diminishing returns argument

Hostility to metaphysics

significance of guiding metaphysical convictions downplayed as

heuristic or attitudinal
context of discover stuff

Inference to the Best Explanation

Scientific Realism: we are warranted in believing the unobservables posited by best explanatory scientific theories really exist.
Argument from the best explantion

if a theory explains the data better than any other theory
we have good reason to think it true
which means we have good reason to think that whatever unobservables it posits really exist

Rejoinder: may be unclear which explanation is best

subjectivity worries: that goodness, like beauty is "in the eye of the beholder"
standards

simplicity
accuracy
applicability

may conflict

simplest theory might not be most accurate
most applicable theory might be either of the two

the computational pain might outweigh the gain in accuracy
or vice versa

Will be unundecidable in principle which unobservable positing theory really is best

aforementioned difficulties in deciding which explantion is best and
can't compare which theories posits correspond to reality since the reality is unobservable
finally, more fundamentally, it can be doubted that explanatory power evidences truth

why should simplicity, accuracy, and applicability of a theory
bespeak its correspondence to reality

maybe reality ain't simple
false theories may perform admirably in predicting & explaining

Newton's theory of gravity.
Ptolemaic theory of the solar system.

was completely false
bore no relation to what what actually up there in the sky
but was predictively & explanatorily quite a good theory

Concerning the fluidity of the observed-inferred distinction

Fictionalist can allow extentions of the senses by instrumental assistance

what's crucial is that the instrument should be tracking some real feature of the environment
cross checking gives some assurance of this: e.g., similarity of images from

MRI
ultrasound

And still insist that some things -- e.g. van Frassen's canditates -- are forever on the unobservable side of the line

Bas van Frassen

"All we are entitled to assert by any evidence which supports a hypothesis about the unobservable is that things are as if there were forces or photons, or whateve the unobservable entities in question are." (118)
"The mere fact that postulating unobservable entities provides some explanatory account of some observed regularity is in itself no reason for belief in the entities." (118)

Scientific Laws and the Representation of Reality

Underdetermination argument

Theory is underdetermined by observational data

for every finite data set
there are infinitely many theories which will predict/explain that data
all these will save the phenomena or be empirically adequate

Anti-Realist Conclusion: Empirical adequacy is no reason to think

that the model proposed by theory: i.e. the unobservable mechanisms posited to capture the phenomena
is true: i.e., represents any corresponding realities

Empirical inaccuracy issues: raise doubts extending even to how totally, precisely, or well theories capture their supporting data

Theories are useful idealizations not accurate representations

Newton's first law: "Every body continues in a state or rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it."
Newton's Law of Universal Gravitation says every body in the universe attracts every other with a force proportional to the product of their masses and inversely proportional to the square of their distance one from the other.
Follows from UG that there are no bodies -- without forces impressed upon them -- such as the first law describes

Modern scientific demand for mathematical precision

it may well be doubted that reality is as tidy and orderly as our theories would have it
mathematical precisiion seems a methodological requirement
not a substantive "discovery"

not as if the world really is mathematically governed
rather we have decided to see it, as it were, through mathematical glasses

Peirce: `the most refined comparisons' or measurements of physical quantities

"fall behind the accuracy of bank accounts" and are more on a par with
"upholsterer's measurements of carpets and curtains"

we characteristically fudge the data to make them exhibit the regularity our theories require of them

so-called "bridge principles" tell us how to apply the theory in specific circumstances
ad hoc corrections and the like

Nancy Cartwright's Conclusions

none of these accuracy issues militates against the possibility that

science discovers genuine empirical regularities
and even new entities or phenomena

but they do militate against the classical absolutist scientific ideal

that the aim of science is always the production of more general, accurate, and comprehensive accounts of a whole given level of existence
ultimately culminating in the grand ideal totally accurate theory of absolutely everything.

this ideal may be unattainable not due to our cognitive & life-span limitations (which all allow)

but because nature itself is mathematically untidy
and can't be divided into clearly demarcated natural kinds

concluding suggestion: perhaps everything we really want from science can be had without assuming this ideal

The Absolute View of the World

Focusing in on the issue

What it's not

Not the general skeptical issue of whether there's a mind independent world (pace Berkely)
of which it's possible to have genuine knowledge (pace Hume)
or of whether it's possible to know anything at all (pace Descartes)

The issue

accepting our sensorily and culturally given account of the world as a starting point
to what extent can we go beyond this starting point to achieve

knowledge of things as they are in themselves
apart from our particular perspectives

personal
cultural
biological

to what extent we can get at objective realities behind the subjective appearances

Copernican example

plainly seems to us from our prescientific perspective

that we stand still
and the sun & moon and stars move across the sky

Copernican hypothesis tell us

the way things really are
is different than the way they seem

The Claim on Trial

science produces descriptions of reality
increasingly less relative to our subjective standpoint
and increasingly more absolute and objective
science reveals entities and properties

causally more fundamental
than the entities and properties naturally & culturally given.

Manifest Image vs. Scientific Image (Sellars): the Relation at Issue

Manifest image: the world as it it naturally and culturally given to us or as it appears

sensory qualities: colors, sounds, smells, tastes, etc.
entities: mid-size dry goods

Scientific image: this portion of the world as science describes it

colorless electro-chemical processes
occurring in our visual apparatus (in the case of colors)

Received -- scientifically realistic -- view

the world as it really is does not contain color as a fundamental property
color and the experience of color are due to the interaction of more basic properties that science describes

color itself: optics (wavelength, reflective indices, etc.)
color experience: electrochemistry of the retina and other visual apparatus

Convergence Argument

We know that certain species with whom we cohabit this globe

have sensory capacities we lack

echolocation: bats
magnetic direction finders
dogs: range of sounds & odors ndectectable by us

so their manifest images must be different than ours

We can easily imagine other scientifically minded species

with radically different sensoria & manifest images
nevertheless converging, with us, towards a shared scientific image

We thus arive at the idea of an absolute conception of the world

i.e., of the world as it is in itself
independently of any particular mode of perceiving
to which all particular modes of perceiving could be related

Further Expectations & Allegiances

essentialism: since this absolute conception will "carve nature at the joints", i.e., pick out the truly causally salient features
reductionism: the manifest image properties and objects will be explained in terms of or reduced to properties of and relations between entities in the scientific image
unity of science: similary high level scientific properties and entities will be explained in terms of or reduce to properties of and relations between entities recognized by the lower level -- more basic -- sciences

psychology reduces to neurophysiology
neurophysiology to biology
biology to chemistry
chemistry to physics

Reservations About the Absolute Picture Just Envisaged

It's more of a philsophical ideal regulative of inquiry than a scientifically justified thesis supported by observational evidence or entailed by accepted scientific theories and laws.
Even if there is a way the things absolutely and in itself independently of any observers or their perspectives and sensory equipment

inaccessible to us
even unapproachable

Even if there is not a way things are absolutely and in themselves independently of any observers or their perspectives

science might still be an intellectually worthwhile in revealing regularities within our images

naively manifest
scientifically manifest

and practically beneficial in yeilding useful technological applications

Partial Views: Shröedinger's Cat

Scenario

There's a room -- a gas chamber -- rigged with a geiger counter
along with a quantity of radioactive material that has 50% chance of undergoing nuclear decay thus giving off radiation in the next hour.
The geiger counter is rigged to a device that will cause the release of cyanide gas: if the counter clicks, the pellet falls.
There's this cat in the room.

The puzzle: quantum mechanical indeterminacy meets physical & common-sense determinacy

According to the quantum mechanical description we cannot speak definitely of the decay-nondecay of the nucleus at a given time

the state of the system is represented as a superposition of possible value

decay
nondecay

it's not in a state of nondecayed/decayed but in an inderminate state

50% decay
50% nondecay

analogy: How was the weather yesterday

not "it rained" or "it didn't rain" but
there was a 50% chance of rain

According to common sense (and the cat)

it's dead or alive and not in some indetermediate state
at the end of the hour

Shröedinger's issue: how to reconcile these

the particle being in neither definite state
the state of the cat being causally dependent on the state of the particle
the cat being either definitely alive or definitely dead after an hour

Proposed solutions

Wigner: the intervention of the consciousness of the observer causes the "collapse of the wave packets" into a single definite state

EXPOSITION

the observer looks in and the cat -- which previously was not definitely either -- either lives or dies
mind-matter interaction is a problem for understanding the very physics of the world (not just psychology)

CRITICISM

surely the cat is alive or dead prior to my looking in (the incredulous stare)
difficult to accept the consequence that "`in the thousands of millions of years before conscious life emerged in the world -- and still today in those extensive parts of the universe where no conscious life has yet developed -- no wavepacket has ever collapsed, no atom for certain decayed" (J. Polkinghorne as cited by O'Hear, p. 138)
the mechanism whereby this is supposed to happen -- say in the cat case -- is underdescribed

Copenhagen interpretation: superimposition is eliminated and definiteness achieved when things are sufficiently large

EXPOSITION

the quantum-mechanical description is to be read as saying nothing about an individual state: Larry has one child.
speaks only of the decay/non-decay ratio in a sample: Average US adult has 2.3 children.
fictionalist tack (O'Hear, p. 139)

"The superposition of states is not taken literally
the fuzziness is to be regarded as a function of our theories rather than of reality itself."

CRITICISM

the explanation isn't explanatory: it just redescribes the problem
the mechanism whereby this is supposed to happen -- say in the cat case -- again is unspecified
fictionalism seems to many a considerable price to pay: implication

some parts of our world are inherently unknowable
all we can do is produce probablistic and fuzzy descriptions of it

COMMENT (LH)

if the story is that really something definite -- but unknowable -- is happening at the quantum level
then there's no mechanism required for how things become definite
the question becomes how they become knowable

Related Phenomena & Issues

wave-particle duality as shown by slit-screen experiments
Heisenbergian uncertainty having to do with the simultaneous meaurement of a particle's

velocity
position

Hidden variable approach: the indeterminacy is merely epistemis & things are determined one way or another by factors presently unknown

EXPOSITION

In the slit screen case: there are both

particles (which can be seen)
and associated waves (inferrable from the interference effects)

Shröedinger's Cat: as yet unknown forces determine the exact moment of decay
"God doesn't play dice with the universe."
And there's no problem of determinacy arising out of indeterminacy; there is no indeterminacy.

CRITICISM

unsimple:

where the undeterministic interpretation has one thing: wave-or-particle
Bohm's hidden variable approach has two

ad hoc

whenever there's indeterminacy
we postulate X: the unknown indeterminacy-be-gone factor

has not found great favor among physicists

Wheeler and Graham's many worlds hypothesis: each of the indeterminate things definitely happens in some world or another

EXPOSITION

there's worlds in which the cat dies & in ones in which it lives
in those world's where it dies there's a

1st minute world: pellet dropped in the first minute
2nd minute world: pellet dropped in the second minute

CRITICISM

intrinsic implausibility (the incredulous stare, again)
unhelpfulness: doesn't explain why the cat dies in this world
problems about cross-world identity: compare essentialism

is there a world in which I am seated here and now?
is there a world in which I went into auto repair instead of philosophy?
is there a world in which I am a woman?
is there a world in which I am a chimpanzee?
is there a world in which I am a fish?
a daffodil?

Morals of the Discussion

Escapes are too costly

consciousness hocus pocus
antirealism
inelegant & flawed hidden variable approach
wild & crazy multiple worlds approach

So we are left with Shröedinger's problem

how to integrate different theoretical pictures

of an inderminate micro-world
of a determinate macro-world

into a single unified picture.

Shröedinger's puzzle a very drammatic illustration of a more general reconciliation problem
Cautionary conclusion: "We should be wary of thinking that we are close to an absolute picture of the world, in which all the elements mesh smoothly and seemlessly." (143)

further details to be worked out
an impossible dream . . . stop trying to reconcile the unreconcilable

theoretical diversity
multi-theory-ism