scientific rationality, formal or informal

8/11/2019 Scientific Rationality, Formal or Informal

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The British Society for the Philosophy of Science

Scientific Rationality, Formal or Informal?Author(s): Jiang TianjiReviewed work(s):Source: The British Journal for the Philosophy of Science, Vol. 36, No. 4 (Dec., 1985), pp. 409-

423Published by: Oxford University Presson behalf of The British Society for the Philosophy of ScienceStable URL: http://www.jstor.org/stable/687400.

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2/16


3/16

410

Jiang

Tianji

ation

of the

standard

conception

of

scientific

rationality.

Kuhn's

heretical

conception

will

be vindicated

against

charges

of

irrationalism in

section

3,

and

other

models of

informal

rationality

will be

briefly

discussed in

section

4.

2

STANDARD

CONCEPTION OF

SCIENTIFIC

RATIONALITY

Logical positivists

and

Popperians

have believed that

science

proceeds

by

following

a

distinctive

method,

the scientific

method,

and

rationality

is

nothing

other than

acting

in

conformity

with the

norms of this

method.

They

have

aspired

after an

explicit

formalisation of

rationality.

In

their

opinion,

rationality

is identified with commitment to this formalisable

method.

From Mill

to

Carnap

and

Hempel,

influential

philosophers

of science

have

continued to believe that

some

thing

like a

formal method

('inductive

logic')

underlies

empirical

science and that

continued work

might

result

in

an

explicit

statement of this

method,

a formalisation of

inductive

logic

comparable

to the

formalisation of

deductive

logic

which was

achieved

by

Frege

and others. If

such a method were

discovered,

then

scientific

rationality

would be identified with

the

possession

and

employment

of this

method. This influential view was voiced

by

I. Scheffler as follows:

Underlying

historical

changes

of

theory,

there

is

... a

constancy

of

logic

and

method,

which unifies each scientific

age

with that which

preceded

it

and

with

that which

is

yet

to follow.

Such

constancy comprises

not

merely

the

canons

of

formal

deduction,

but also those criteria

by

which

hypotheses

are confronted

with

the test

of

experience

and

subjected

to

comparative

evaluation

(Scheffler

[19671, PP.

9-1o).

Proponents

of this view admit that 'we do not .

..

have

explicit

and

general

formulations

of

such

criteria at the

present

time',

but

they

insist

that criteria

'are embodied

clearly

enough

in

scientific

practice

to enable communication

and

agreement

in a wide

variety

of

specific

cases

(and such)

communication

and consensus

indicate that there is a

codifiable

methodology underlying

the

scientific

enterprise'

(ibid.).

It was

assumed

that there are

universal

principles

of

theory-acceptance

implicit

in

scientific

practice

at least since the time modern science

began;

in

other

words,

there

is a

rationality implicit

in the work of natural scientists

since about the time

of

Newton,

this

explains

why

this work is so successful.

It is

possible

that these criteria of

rationality

are not well-understood

at a

given

time and

incorrectly applied

on occasion. But it was further assumed

that

by

i800

or

1850,

this

rationality

was

fully operative

in the work of

major

natural

scientists,

so that we could

speak

of 'the'

scientific

method.

Thus for

logical positivists,

it was assumed that scientific

rationality

takes

the form of a

logic.

It

is, therefore,

formal. It is

given

once and

for

all;

it

never

develops

or

changes.

This was not to

say

that

all

scientists

employ

it


4/16

Scientific Rationality,

Formal or

Informal?

41I

equally

well. But

the

assumption

was that there is a norm of

rational

procedure

which

all scientists

should

endeavour to

comply

with and

all

philosophers

should

endeavour to

disclose.

Logical positivists

have at-

tempted

at an

explicit general

formulation

of the

principles

of

rational

acceptance.

Take

Hempel's

logic

of

confirmation,

for instance. In his

'Studies in

the

Logic

of

Confirmation',

Hempel

is

engaged

in a

search

for

'general objective

criteria

determining

whether

.

..

a

hypothesis

H

may

be

said to be

corroborated

by

a

given

body

of evidence E'

(Hempel

[19651,

p. 6).

His aim

in the

essay

is to

provide

definitions of

the

concepts

of confirmation

and disconfirmation which

characterise those relations

in a

purely

formal

way:

the criteria of confirmation 'should

contain no reference to

the

specific

subject

matter of the

hypothesis'

(ibid.

p.

Io).

For

Hempel,

one

ought

to

be

able to tell

simply

by

looking

at the

logical

forms of a

hypothesis-sentence

and an evidence-sentence whether the confirmation relation holds between

them,

just

as

one

can tell

simply

by inspecting

the

logical

forms of

premise-

sentences

and the

conclusion-sentence whether the

implication

relation

holds between them.

The

search,

then,

is

for formal

syntactic

criteria

of

confirmation

analogous

to the

formal criteria for the

validity

of

deductive

arguments.

What

would count as evidence for an

hypothesis

is determined

by

the form of

hypothesis-sentences

and

evidence-sentences,

not

by

their

content.

The

situation seems from

an

epistemological point

of

view ideal: the

justification of hypotheses becomes a very straightforward matter. But, alas,

reality

has

a

way

of

eluding

the

ideal,

for

actual evidential

relations

in

science

are

not

captured by

such

analysis

of

confirmation.

The

analysis Hempel

provides

is

of a

formal,

syntactic

relation between

sentences. This

relation

holds

only

between

sentences

containing

the same

predicates.

But most

interesting

scientific

theories

are not

evidentially supported

by

statements

containing

the

same terms as

occur in

the

theory,

but

by

statements

containing

quite

different

kinds of

terms.

Therefore

the

Hempelian

approach

is

applicable

only

to

a

restricted set of

evidential

relations,

the

relation between observation statements and theories which are merely

generalisations

of

observation

reports.

Generally

speaking,

the

logical

positivist

account of

theory-acceptance

is

oversimplified.

In

his inductive

logic

Carnap

treats all

logical

consequences

as

having

the

same

evidential

relationships

to the

hypothesis they

support:

no

distinction

is drawn

between

those known

in

advance

and the

'novel'

ones.

It

would

be

very

difficult for him to

incorporate

such a

distinction

into

his

scheme,

because there

is no

way

to know

by

a

simple

inspection

of

an

observation

statement whether

it

would

count

as

'novel'

or

not.

Only

the

history of the theory in question can tell one that. But the positivists have

adopted

a

very

abstract

model of

rationality

in

which

only

the

formal

structure of a

theory

and

the

empirical

evidences

drawn from it are

relevant

to

theory

evaluation.

They paid

no

attention to the

prior

historical

development

of

a

theory

and the

different

degrees

of

support

conferred

by


5/16

412

Jiang Tianji

different

sorts

of

evidence

upon

it.

According

to

their intuitive

principles

based

on

an a

priori

notion

of

evidence,

all

accepted

consequences

lend the

same

degree

of

support

to the

theory

or the same

degree

of disconfirmation

if

they

are refuted. What

they emphasised

is

the

mere fact that

theory

and

evidences

are

deductively

related.

They

can

easily

set

up

a

postulational

system

of

plausible principles

of

evidence,

the trouble

is that this does

not

apply

to what

actually

goes

on

in

science.

It is now

generally

agreed

that,

in

actual

scientific

practice,

what counts

most of all in favour

of a

theory

is not

just

its success

in

prediction

but

its

'dynamical

character' or its

'fertility',

its

ability

to meet

anomaly

in a creative and fruitful

way.

This is

something

which

manifests

itself

only gradually

over

the course of

time;

one cannot

attest

to it

until the

theory

has

survived

many

tests and been extended

in

illuminatingly

new

ways.

Time

plays

an

essential role

here. Whether such

actual evidential

relations

can be

formalised

or

not,

we have

yet

to see.

Popper

and

Popperians

have

attempted

to

formulate

a more

complex

model of

rationality

than

that of

logical

positivists.

But with

them

they

shared

the

assumption

that

there are norms

of the scientific

method,

an

unchanging

set of intuitive

principles

underlying

validation

in science.

According

to

Popper,

a scientist

ought

to

act in accordance

with the dictates

of

the method

of falsificationism:

propose

testable

theories;

not

investigate

ad hoc

theories;

accept

that

theory

for further

theoretical and

practical

purposes,

which is best

corroborated;

select

a

simpler hypothesis

because

it

is

more testable

than a less

simple

one;

and so on.

Popper

has

claimed that his

method

will

give

us

a better chance

to achieve the

goal

of

epistemic progress.

In this

model of

rationality,

three

criteria

are offered

for rational

theory-

choice:

first,

the

criterion

of

prior

appraisal;

second,

the criterion

of

posterior

appraisal,

and

third,

the criterion

of

appraisal

for theories

which

are known

to be

false.

The

notions

of

empirical

content

and

explanatory

power,

etc.,

are defined

in

purely

logical

terms

by

Popper.

In

his

explication

of

empirical

content

(or

falsifiability),

one

important

problem

concerns

the

measurement

or com-

parison

of contents.

There

are

objections

that content

comparison

is

impossible

because

contents

of

theories

are not subsets

of each

other.

But

Watkins

still

attempts

to show

that

at least

the idea

of

comparing

empirical

content-a

pre-testing

concept-can

be

rescued.

As

to

theory

testing,

Popper

thinks

that

only

a novel

fact

can

really

support

a

theory.

Thus

he introduces

the ideas of

background

knowledge

and

severity

of a test

to account

for

the distinction

between

'evidence'

known

in

advance

and

verified

prediction

of a novel

fact,

a

distinction

which cannot

be made in

Carnap's

theory

of confirmation. The

logical

relation of

deducibility

cannot

of

itself

convey

this

difference;

a

temporal

analysis

of

some

kind is needed.

But

success

in

novel

prediction

is not

fertility.

Fertility

is not

a matter of

prediction

at

all.

He concedes the

importance

of

time

order

in

theory appraisal

but

never

quite

comes

to

viewing

fertility

as a criterion

of

appraisal.


6/16

Scientific

Rationality,

Formal or

Informal?

413

Finally,

Popper's

formal

concept

of

verisimilitude

will

allow

two

false

theories

to

be

compared

with

respect

to their

truthlikeness,

the

theory

with

more

truth-content

or

less

falsity-content

is

to

be

preferred.

However this

concept

of verisimilitude

has come under criticism from D. Miller

and

P.

Tichy,

and

it

seems

that

a

precise

definition of

verisimilitude couched

in a

formalised

language

will

never

be

possible,

because truth-contents

and

false-contents

are

not

comparable.

Therefore,

both

the

problem

of

pre-

testing

measurement

of content

and the

problem

of

post-testing compara-

tive

verisimilitude

have met with severe technical

difficulties,

and the

concept

of

degree

of corroboration

will

not be

very

useful

if all

theories have

been refuted

or are

bound

to

be

refuted.

The

model of

Popper's

thus has its

own unsolvable

difficulties,

not to

speak

of its

inapplicability

to

theory-

choice

in

actual

scientific

practice.

Now we come

to

Lakatos's

improvement

of the

Popperian methodology.

Lakatos

took

one

step

further

in

insisting

that

the

unit for

appraisal

is not the

theory

taken at a moment

of

time but the

theory

considered

in

terms of

its

entire historical

career,

what he

called

a

'research

programme'.

He

had two

main criteria for

the

appraisal

of

scientific

research

programmes.

One is

increase

in

empirical

content,

at least some of which

has been

experimentally

confirmed. The other is

the

idea that a research

programme

is better than

a

competitor

if it has more

heuristic

power, potential

for

creating

'evidential

support',

i.e.,

if it

makes

possible

the construction

of

a

sequence

of

theories

with

increasing

'evidential

support'. Roughly,

a

research

programme

is

fruitful

if it

can lead to a

series

of

theories which

produce

novel

knowledge.

It

appears

that

heuristic

power

is

scarcely

more than

the

capacity

to

generate

increase in

successful

prediction.

Urbach has

attempted

to

show that the

heuristic

power

of a

research

programme

can

be

objectively

determined. For

Lakatos,

a research

programme

is

better

than

its rival if it has

more

'evidential

support'

and more heuristic

power,

i.e.,

power

to

create theories

with

'evidential

support'.

Thus

everything hinges,

again,

upon

the

idea of

'evidential

support'.

But

prediction

failures

are not

relevant to the

appraisal

of

research

programmes.

A

major

problem

for

Lakatosians is

how

to rule

out ad

hoc evidential

support.

Worrall

suggests

that

those facts which

have been

used

in

the

construction of the

theory

in

question

cannot

'support'

the

theory.

Worrall

maintains

that

it can

be

objectively

determined

whether a fact was

used

in

constructing

a

theory.

If

a

fact has

been used once in

a

theory,

then

the

same

fact

can

only

be

explained

ad

hoc

by

that

theory-a

fact cannot

be used twice.

Lakatos

comes

near

to

the

criterion of

fertility

with his

emphasis

on the

historical

development

of a

programme,

but

not

quite;

it

seems what is

sought

in a

'good'

development

is mere

increase

in

successful

prediction.

Of

course Lakatos

put emphasis

on

the

importance

of

heuristics for the

development

of science. But

this heuristic is said

to set a

'pre-conceived'

plan

for

the research

programme.

And heuristic

power

is

reduced

to

power

to

generate

increase in successful

prediction.

Thus the

principal

criterion


7/16

414

Jiang

Tianji

for

rational

theory-choice

is excess

evidential

support,

not

different from

what

is

dictated

by

falsificationism:

chose the

best corroborated

theory.

Just

like

falsificationism,

its

formal

approach

to

rationality

cuts

itself off

from the

particularity

and

peculiarity

of the historical

situations where

scientific

theory-choices

take

place. Necessarily,

what

appears

to

be

development

of a

theory (a

scientific

research

programme)

is

really

a

sequence

of

classes

of

propositions (theories)

logically

related to one another as

specified

by

method.

The

fertility

of a

theory,

on

the other

hand,

refers to the

theory's

proven ability

to

take

up

new forms which are not

deducible from the

previous

versions,

but which are

suggested by

them,

according

to Ernan

McMullin's account

(see

his

[1976], pp. 398-402).

The

important

relation-

ship

then becomes that of

suggestion,

holding

between a

previous

and a

later

version of

the same

theory.

It is a

very significant

fact

that,

as McMullin

points

out,

this

suggestion

relation is not a

purely logical

one,

but

necessarily

dependent

on

the historical record. The

fertility

of a

theory

would then be

conceived in

terms

of

the

developmental

transformations it has

undergone

to solve new

problems,

where later

formulations are

not

inferable from

previous

ones,

but

suggestible by

them in the

light

of the

historically

available evidence. We cannot

hope

to state

precise

rules

for

the relation of

suggestion.

But Lakatos did believe that the

methodology

of scientific

research

programme

can

be

characterised

by general

rules

that

would be

binding

and

consciously

or

instinctively

observed

by

scientists.

Lakatos

and Lakatosians claimed with the

help

of case studies that the

evaluative criteria

which scientists

actually

use

are those described

by

the

methodology

of scientific research

programmes.

It was claimed that when

scientists

fail to

conform to

Lakatos'

methodology

it

is because of

external

pressures.

That is to

say,

when

they

are

acting rationally, they

act

in

accordance

with

the

dictates of this

methodology;

when

they

are

acting

irrationally,

then

they

deviate

from them. Therefore this

methodology

is an

explicit

formulation

of the universal rational

method

underlying

empirical

science. Lakatosians

expressed

views about the

constancy

of scientific

method

just

like those

of

logical positivists

as

voiced

by

I.

Scheffler.

Elie

Zahar,

for

instance,

has

this to

say:

MSRP

entails

that

the

presystematic

methodology

instinctively

used

by

scientists in

judging

individual achievements

did not

change

very

much

over the

centuries,

say

from the

time of

ancient

Greece

until

the

present day.

MSRP

does not

of course

presuppose

absolute

stability,

but

it nonetheless

implies

that deviations

from

its

norms

have

been

in

the

nature

of

local fluctuations

very

different

in

magnitude

from

large

scale

scientific revolutions.

This

stability thesis, namely

that

there have

been

no

methodological

upheavals

on

a

par

with scientific

revolutions,

may prove

too

strong.

Still

the

stability

thesis is

to

my

mind

a

very interesting

working

hypothesis

which

ought

to be

investigated.

.

.

.

Many people

have a

strong feeling

that intuitive

methodology,

like intuitive

logic,

has

been

largely

stable

(Zahar

[1982]).

He seemed to

imply

that Lakatos'

methodology

is this

instinctive meth-


8/16

Scientific

Rationality,

Formal or

Informal?

415

odology

made

explicit,

that is

why

scientists

would

tacitly

subscribe

to it

if

they

are not

under

external

pressures.

From

what

is described

above,

it

follows that

Popper

no less than

Carnap,

and Lakatos no less than earlier

Hempel,

would

equate rationality

with

formal

rationality.

Formal

rationality

was

regarded

as actual

rationality

in

science, i.e.,

as

explicit

statement of the

rationality implicit

in

scientific

practice.

Their models of

rationality

are based on the

following

assumptions:

I.

There is a

unified

scientific method or

methodology

which has

been

instinctively

used

by

almost all scientists in all

ages

or at least from

the

time when real science

began.

This

is

the

doctrine of

unity,

universality

and

stability

of

method.

2.

The instictive

methodology

or

implicit rationality

can

be formulated and

formalised,

even

if

we do not

yet

have

such

a

formulation at the

present

time. This is the

theses of

formalisability

of method.

3.

The formal method or

formalisable method can be used to achieve

our

objectives

in

science,

be

it

the

discovery

of

truth,

epistemic

progress,

explanation

and

understanding, prediction

and

technological

control,

problem-solving,

and

what not. This is the thesis of

rationality

of

method.

4.

The formal or

formalisable

method also serves as

a

demarcation

criterion

between

science and

other human

pursuits,

between science

and non-

science or

pseudo-science.

It is

the

defining

characteristic of

science.

This

is the

thesis of

essentiality

of

method. From

this it is

concluded

that the

formal method can

serve as

the

very

definition of

rationality.

3

VINDICATION

OF

KUHN'S

CONCEPTION OF

INFORMAL

RATIONALITY

This standard conception of rationality is rejected by Thomas Kuhn, the

leading proponent

of a

more

complex

view of

scientific

rationality.

Kuhn has

challenged

all

the above

assumptions

of the

standard

conception.

According

to

the

standard

conception,

the

crux of

rationality

is

the

acceptance

or

rejection

of

beliefs on

the basis of

evidence.

Whether

the

inductive

support

of

logical

positivists,

the

corroboration of

Popper

or

the

evidential

support

of

Lakatos,

all

these

are more or

less

formalised

accounts of

evidential

relations

holding

between

the

theory

being

tested

and

observations.

Rationality

of

the

decisions of

scientists

consists in

the formal

relationships

they bear to logic, on the one side, and to empirical facts on the other.

Experience

and

logic

can

determine

uniquely

the

acceptance

or

rejection

of a

theory.

For

Kuhn,

this is

possible

only

in

normal

science for

determining

the

validity

of an

articulation or an

application

of

an

existing theory.

Whole

theories

or

paradigms

cannot

be

judged by

the same sort of

criteria that

are

employed

when

judging

a

theory's

individual research

applications,

he

said:

EE


9/16

41

6

Jiang

Tianji

Observation and

experiment

can and

must

drastically

restrict

the

range

of

admissible

scientific

beliefs,

else there would be no

science. But

they

cannot alone determine a

particular body

of

scientific belief.

An

apparently arbitrary element,

compounded

of

personal and historical accident, is always a formative ingredient of the beliefs

espoused by

a

given

scientific

community

in

a

given

time

(Kuhn

[1972], p.

4).

Because of this

arbitrary

element,

the outcome of

theory

choice cannot

be

dictated

by

logic

and

experiment

alone. Therefore

any

formal

account

of

evidential

relations would not

apply

to actual scientific

practice. Objecting

to the

positivist

and

Popperian

models

of

rationality

Kuhn

said,

both

of

them assume

that 'the

problem

of

theory-choice

can be resolved

by

techniques

which are

semantically

neutral.

The

observational

consequences

of both theories are

first stated in a shared basic

vocabulary

(not necessarily

complete

or

permanent).

Some

comparative

measure

of their

truth/falsity

count

then

provides

the basis

for a choice between them. For

Sir Karl

Popper

and his

school,

no less than for

Carnap

and

Reichenbach,

canons of

rationality

thus

derive

exclusively

from those of

logical

and

linguistic

syntax'

(Kuhn

[1970],

p. 243).

Their

assumption

of the

rationality

and

essentiality

of a formal

method for

theory

evaluation is

radically rejected by

Kuhn.

Now come to Kuhn's

positive

views

on

theory

choice.

First,

he

affirms

that

theory

choice

is

definitely

rational,

there

being good

reasons

of the sort

usually

described

for

choosing

between

competitive

theories.

Second,

these

reasons constitute

values to be used

in

making

choices rather

than rules of

choice.

There cannot be

any

shared

algorithm

by

the

use

of which

all

members

of a scientific

group

will reach the same decision.

On the

contrary,

accuracy, simplicity,

scope,

fruitfulness,

and so

on,

constitute a shared

ideology

for the

group.

Scientists who share

the same

ideology

may

nevertheless

make different

choices in the same

concrete situation.

Group

behaviour

will

be

affected

decisively by

the shared

commitments,

but

individual

choice

will be a function

also of

personality,

education,

and

prior

pattern

of

professional

research.

Therefore individual scientists

will not all

apply

the same values

in the same

way.

Even

if

they agree

about

the

importance

of the various

values,

there

would

remain

the

problem

of

combining

them all

into one

precise

overall criterion

which would

de-

termine

which of

two

competing

theories

to

accept.

But

there

is no

unanimity

at all as

to the relative

weights

that

are to be

assigned

to different

values

in the overall

comparison

of theories.

Third,

the choice

between

competing

theories

lies

in the hands

of the

group

of

specialists.

These

specialists

share the

same commitments.

Even

though they

don't share

precise

criteria for

theory

choice,

and even

though

their

preference

is

determined

in

part

also

by idiosyncratic

factors,

there does

in

fact,

in the

process

of

a

controversy

over

the relative

merits of

two

competing

theories,

eventually emerge

a consensus

leading

to

the

acceptance

of one of

the

rivals.

Though

there are

no

explicit

rules

of

acceptance

for

Kuhn,

he neverthe-

less

offers what amounts

to a

justification

for the

group

behaviour

in

theory


10/16


Formal or

Informal?

417

choice. Here

Kuhn

argues

that scientists'

modes of behaviour as

exemplified

in

theory

choice

have certain

essential

functions:

'In the absence

of alternate

mode

that would

serve

similar

functions,

scientists

should behave

essen-

tially

as

they

do

if their concern

is to

improve

scientific

knowledge'

(Kuhn

[1970],

p. 237).

Kuhn

regards

all behaviour essential to scientific

develop-

ment as

rational;

since

scientific behaviour

in

theory

choice

conduces to the

improvement

of scientific

knowledge,

this

is also an

argument

in favour

of

the

claim that scientific

activity

is

rational.

Now

the

crucial

question

is: is

theory

choice

as characterised

by

Kuhn

really

rational? There

are at least

several

objections.

First, many

philosophers

insist that

an action

ordecision

in science

cannot

be

considered

rational unless

it is based

on

logical

or

methodological

rules

which are

objective

in the sense that

different scientists

following

the same

rules

and

provided

with

the same

information

will

arrive

at

the

same

decision.

The basic

assumption

is that

all

rationality

should be

equated

with

formal

rationality.

Since

Kuhn would not have

anything

to do with such

rules,

decision

as to which of the

competing theory

is

to be

chosen cannot be

based

on

logic

or

methodology,

but rather based

on a value

system

or

ideology,

the

application

of which

in

a concrete

situation

will

not lead

to

unanimous decisions

by

different

scientists.

Personal

factors

have to

be

taken

into

account,

and

what

actually

determines

a

decision

is individual

judgement

rather

than

general

rules. But

according

to the

objection,

such

personal

factors

dependent

on

historical

contingencies

are

irrelevant

to

rational

theory

choice. Since for

Kuhn,

scientists

actually rely

on

sub-

jectivistic

and

psychologistic

criteria

for

choosing

between

competing

theories,

such choice

is not

rational,

it is irrational. Kuhn is accused

of

irrationalism.

This

objection

is

untenable.

On

Kuhn's

view,

both the shared values and

personal

factors are relevant

to

individual

decisions.

Because

perception

and

judgement

are

involved

in

applying

values in a concrete

situation,

each value

can be

judged

quite differently,

individual

variability

in decisions is

naturally

to be

expected.

But individual decisions are

not

final,

they

generally

take risks

and

might

be

wrong.

Still

they

are not

irrational,

because

they

are not

made

arbitrarily

without reasons.

And

they

do

not violate

any

accepted

rules

because

there

are

no

such

binding

rules in

scientific

practice.

What is

important

is

the unanimous decision

belatedly

reached

in

a

group.

Neither

individual choice

nor

group

choice is based

on what is

called sub-

jectivistic

and

psychologistic

criteria,

though psychology

is not irrelevant

because

theory

choice is a human

activity,

and occurs

not

in the 'world

3'

of

Popper,

but in this real world of our scientists.

Second,

from

the

standpoint

of the

objectors,

consensus

eventually

emerging

within the

group

of

scientists,

leading

to

the

acceptance

of a

paradigm,

is not a

rational decision

either,

for

according

to their

conception

of formal

rationality,

the

consensus criterion

is not

objective,

but sub-

jectivistic. Only

the

logical positivists' degree

of

confirmation

or

inductive


11/16

418

Jiang

Tianji

support

and the

Popperian comparative degree

of

corroboration are

objective

criteria

for

theory

choice.

They

seem

to think

that

for

Kuhn

a

group

of scientists

may

choose

any theory they

like so

long

as

they agree

in

their

choice

and therefore enforce it.

This,

of

course,

would

be sub-

jectivistic.

But

nothing

of the

sort is

implied

in

Kuhn's

concept

of

consensus. On Kuhn's

view,

when a

group

of

specialists

reach a

unanimous

decision,

it

is

never

arbitrary,

but must be based on

good

reasons.

It

may

be

a

conclusion reached

at the end of a

process

of

deliberation

or

argumentation,

or

it

may

be

more or less

easily

arrived at as a

result

of the

relative

unanimity

of the

professional judgements

of

these

specialists.

Therefore

the consensus

among

scientists is

objectively

arrived

at,

and is at least

partly

a

product

of

objective

social conditions

and

institutions.

As

Kuhn

well said:

Recognition

of the

existence

of

a

uniquely

competent professional group

and

acceptance

of

its

role

as the exclusive arbitor

of

professional

achievement has further

implications.

The

group's members,

as individuals and

by

virtue

of their

shared

training

and

experience,

must be seen as

the

sole

possessors

of the

rules

of

the

game

or

of

some

equivalent

basis

for

unequivocal judgements

(Kuhn

[1972], p. 168).

Why

should scientific

communities be able to reach

a

firm

consensus

unattainable

in other fields like

art and

philosophy?

According

to

Kuhn,

science

is

the

only

field that

shows

progress

in

increasing

the

number

and

precision

of the solved

problems.

The nature of scientific communities

'provides

a virtual

guarantee

that

both

the

list of

problems

solved

by

science

and

the

precision

of individual

problem-solutions

will

grow

and

grow'.

At

least,

the nature

of

the

community

provides

such a

guarantee

if

there

is

any

way

at

all

in

which

it can

be

provided.

What

better

criterion

than the decision

of

the

scientific

group

could

there be?

(Kuhn

[1972],

p. 170).

If

for

Popper,

'there is

nothing

more rational than .

. .

the method of science'

(Popper

[1972],

p. 27),

then,

Kuhn

should have

said,

'there

is

nothing

more

rational than the decision of a

scientific

group'.

But

unlike

logical

positivists

and

Popperians

for whom

inductive

support

or evidential

support

would

be the

sole

or at least the

principal

criterion

for

theory

acceptance,

the

ability

to solve

empirical problems

is for Kuhn neither

the

unique

nor an

unequivocal

basis

for

paradigm

choice

by

a scientific

group.

There can be

no criterion of that

sort,

and no

criterion is needed.

The

group's

decision is based

on

examples

of

what

a scientific

theory

achieves

and

on

judgements

of value.

That is

why

there is no formal

rationality,

informal

rationality

is

all we have.

Third,

there

are still some other

philosophers

who would

neither

denounce Kuhn's

model of

theory

choice as

irrational,

nor concede

that it is

rational.

According

to

them,

'any

kind of

action,

including

scientific

choice,

can

be called

rational

only

if it

can be

causally

linked

to

deliberation

or

reasoning

aimed at

achieving

specific

ends.

Scientific

theory

choice

as

characterized

by

Kuhn would not be rational

in this sense but would

rather

be akin to...

latently

functional behaviour

patterns,

which

serve a

function


12/16

Scientific

Rationality,

Formal or

Informal? 419

they

were

never

chosen to

fulfill'

(Hempel

[I981]).

I think what

Hempel

emphasises

here is

correct,

the

question

whether

an action is rational or

non-

rational

hinges

on this

point:

whether

or not it involves a

process

of

deliberation.

A

spontaneous,

unconscious

action is

non-rational. But

a

deliberate

and considered

judgement,

even

when it is

not the conclusion of

a

cogent

reasoning,

can

be

rational. We should not

suppose

that the

judgements

of a

scientific

group

on

the

comparative

merits of

competing

theories cannot be

causally

linked to

any

deliberation at

all.

The

drux

of the

matter is:

how

extensive

and detailed a

process

of

deliberation

is

required

before it can confer

rationality upon

the

action

that

will

ensue from

it.

If

it

were demanded that

a

scientist

knows

what his alternatives

are,

and he

knows what

the

possible

outcomes

of

these alternatives

are,

and he also

knows what his

preferences

are

among

the

possible

outcomes

(that

is,

if it

were demanded that he must know

what

alternatives will

maximise his

expected utility,

before

his

choice

can

be

rational),

then choices of an

individual scientist are seldom rational.

By

the

same

token,

group

choices

are

very

seldom

rational,

because we cannot

expect any

scientist to know

all

this.

But

why

should

we

demand

of

a

scientist or a

group

of scientists this

knowledge

of all

alternatives

and

especially

of

all

the

possible

outcomes

of

them?

Actions

of

scientists,

including

theory

choice,

can

be rational

if a

less

extensive

and less

careful deliberation is

required.

The

theory

choice as

characterised

by

Kuhn is not rational in

the

utility-maximisation

sense of

rationality.

What is

at

issue is

the

problem

of formal versus

informal

rationality.

The

standard

conception

of

scientific

rationality

identifies

rationality

with

formal

rationality,

commitment to a

formal

method

of

science.

Logical

positivists

and

Popperians

have

attempted

to

'explicate'

scientific

pro-

cedures

as

governed

by

explicit

and

precise

rules. The

acceptance

or

rejection

of

a

theory

is

rational

if it can

be

justified by

some of

these

rules,

otherwise

it

would be

irrational or

non-rational. This

overly

narrow and

abstract

conception

of

rationality

would

relegate

most scientific

decisions

and

beliefs

to

irrationality.

The

contributions of

Thomas Kuhn

consist in

the

liberalisation of

rationality.

Formal

rationality

becomes

only

a

part,

and

may

be an

unimportant

part,

of

rationality,

because scientific

method

in

an

especially comprehensive

and

momentous

context,

namely

in

regard

to

scientific

revolutions

and

theory

change,

cannot be

characterised

by

explicit

general

rules

to

be

observed

by

practising

scientists. It is

obvious that

where

formalisation

of scientific

procedures

is

impracticable

or

unsuccessful,

there

people

have to

rely

on

informal

rationality.

But is it

true that

where

a

formal

method

exists,

no recourse to informal

rationality

is

needed?

Kuhn

seemed

to

imply

this in

what

he said:

That

part

of his

(Karl

Popper's) writing

which

seek

an

algorithm

for

verisimilitude,

if

successful,

would

eliminate all need for

recourse to

group

values,

to

judgements

made

by

minds

prepared

in a

particular

way (Kuhn

[1970],

p.

238).


13/16

420

Jiang

Tianji

I

think that

this is incorrect.

It is

highly unlikely

that

a

complete

formalisation of all scientific

procedures

would be

forthcoming,

and even if

we

got

such

a

formal

method,

in

applying

it

we cannot

dispense

with human

intelligence

and

judgement.

4

OTHER MODELS OF

INFORMAL RATIONALITY

While Thomas

Kuhn

has

established,

in

a more

or

less

descriptive

way,

that

theory

choice is under the

sway

of

informal

rationality, Hilary

Putnam

provides

a

powerful argument against

the

formalisability

of scientific

rationality.

His

central idea

is

that

the

need for an

informal element

is

indispensable for any formal method. The formalised scientific method

depends

on

inputs

which are not formalisable. Take

the

Bayesian

Approach

for instance.

In

computing

the

degree

of

support

of

various

hypotheses

using

the

Bayesian

theorem,

as

'inputs'

we need not

only

the

computable

likehoods,

but also the

prior probabilities

of

the various

hypotheses,

i.e.,

the

'subjective degrees

of belief'

assigned

by

scientists to those alternative

hypotheses

prior

to

examining

the

observational evidence.

It

turns out that

difference

in

the

prior probability

function can lead to violent difference

in

the

actual

degrees

of

support assigned

to

theories.

Putnam

draws

the

conclusion that formal rationality does

not

guarantee

real and actual

rationality.

If

one starts out

with a 'reasonable'

prior probability

function,

then one will

only assign degrees

of

support

to 'reasonable'

hypotheses,

but

if one's

prior probability

function is

'unreasonable',

then

one's

assignment

of

degrees

of

support

to various

hypotheses

will be 'irrational'. This

prior

probability

metric

represents

the scientists'

antecedent beliefs about

the

world.

It

seems

that one

of the

inputs

to the method itself is a set

of

substantive

factual beliefs

(or

degrees

of of

belief).

The

need

for an informal

element is similar

in

other

approaches.

Therefore

it

is

not

possible

to

draw

a

sharp

line between

the content

of

science

and the method

of science. Both

Putnam and

Shapere

lay

stress

on the

dependence

of scientific

method

upon

scientific

beliefs,

and

maintain that scientific

method

changes

constantly

as

the content

of science

changes.

If

the

method of science

changes

constantly,

then the traditional

belief

in a

universal

stable method

is untenable

and the

attempts

to

formalise

it

would

be doomed

to failure.

Putnam has this

to

say,

The

hope

for

a

formalisable

method,

capable

of

being

isolated

from actual human

judgements

about

the contents

of

science

(about

the

world),

and

capable

of

actually

being

stated

seems

to have

evaporated

(Putnam

[1981]).

If from

the

constancy

of

scientific

method

the ideal

of formalisation

is

derived,

and as a result

the

praises

of formal

rationality

are

sung,

and formal

rationality

is identified

with

the

very rationality

itself,

then

from

the

changeability

of scientific

method

we should

be convinced

that

complete

formalisation

is

hopeless

and

informal

rationality

must

be restored to

its


14/16


Formal or

Informal?

421

legitimate

status.

During

the

period

from fifteenth to seventeenth

century,

when new science was

originated

and

developed, general methodological

maxims instead of precise formal rules were put forward by scientists and

philosophers

for the

guidance

of scientific

inquiry.

In

the

application

of

general

maxims to

particular

cases

intelligence

and

judgement

are

required,

thus

it

was informal rather than formal

rationality

that

prevailed

in

scientific

practice

of

that

period.

After a

long

tradition of

attempts

at formalisation

from

Mill

to

Carnap

and

Popper,

it was

Polany

and

Kuhn,

in

the

years

around

i960,

who

first threw off the

tyrannical yoke

of formal

rationality

imposed by logical positivists

and

Popperians. Polanyi

is

sceptical

of the

degree

to

which the skill of

theory-assessment

which

develops historically

in

the scientific

community

can be made

explicit

either

by

scientists

or, post

factum,

by philosophers.

In

his

view,

scientific

rationality

can

never be made

fully

explicit

or even rendered

unambiguous

in

outcome. Kuhn

claimed

that

decision

in

theory-choice

is

based on

ideology

rather than on

logic.

There

cannot be

any algorithm

for

theory-choice

which will

dictate the same

decision for all

members of the

group.

The

upshot

of all this is to

replace

formal

rationality by

informal

rationality.

Other models of informal

rationality

include both

the inferential and the

noninferential ones.

Shapere's

discussion of

principles

of

reasoning

as

having

a central

role

in

many

scientific decisions between

competing

theories

or lines of research is a

clarification of the

functioning

of informal

reasoning

in

scientific

practice.

These

principles

of

reasonable scientific

research are

not formal

rules,

the

reasons

they

provide

for

seeking

a certain

type

of

theory

are of course

not

conclusive.

Shapere

said,

'that

the

reasons were not

logically

conclusive did

not

make them

any

the

less reasons-and

good

ones,

relative to the state of

science

at

that time-nor

did

it

make action in

accordance with

them

any

the

less rational'

(Shapere

[19741,

p.

409).

Therefore

in

accounting

for the

rationality

of scientific

discovery

as well as of

justification

our one

recourse is

to

informal

rationality.

The

non-inferential

models of informal

rationality

are

emphasised,

besides

Kuhn

and

Putnam,

by Polanyi,

Grene,

Toulmin and

Wartofsky.

It

is a form of rational

judgement

modelled on

judgement

in

the

law,

in

medical

diagnosis

and

in

aesthetic

appraisal;

this form

of

informed,

skilled

judge-

ment involves

the

application

of

general

maxims or

directive to

particular

cases,

but it is not

rigorously

rule-determined. It is

rational

in

the

sense that

judgements may

be

defended

by citing

particular

cases,

previous

appli-

cations of the

maxims and the

like.

Wartofsky

wants to

resurrect a

historical

alternative

conception

long

overshadowed

by

the

standard

conception

of

rationality.

This

is the

'heuristic tradition'

involving

'craftsmanlike skill

in

judgement'

and

'tinkering'.

The scientific

theorists

tinker with

ideas

(see

his

[1980]).

This

kind

of

down-to-earth

tinkering

found

in

crafts

allows for

creative

innovation

in

science.

Thus

this

model of informal

rationality

would make

scientific

behaviour both

creative and rational.


15/16

422

Jiang

Tianji

5

CONCLUSION

We

have seen that the standard

onception

f scientific

ationality,

he

model of formal and abstract rationality, is divorced from scientific practice.

This normative

conception

is

in conflict with the historical

fact that

standards

of

rationality

change

over time.

It is the

assumption

of fact-value

dichotomy

that renders the standard

conception

seemingly

invulnerable.

But

starting

from

Kuhn and

others,

philosophers

are

increasingly coming

to

agree

that scientific

rationality

includes an informal

part

whose

importance

is estimated

differently by

different

philosophers.

Both

extreme

positions-

the identification

of

rationality

with a formal

method or the

complete

neglect

of formal

rationality-seem

to be

incorrect. Thomas

Kuhn

gives

formal

rationality its due in normal science. Hilary Putnam would think that each

functioning

of scientific

rationality

includes a formal

part

and an informal

part.

This 'liberation'

of

rationality

from

formal

logic

or normative

methodology

is a

good thing.

Let

us

quote

Kuhn

again:

The

man who

embraces

a new

paradigm

at an

early stage

must often do so

in

defiance

of the

evidence

provided by problem-solving.

... There

must also be

a

basis,

though

it need be

neither rational nor

ultimately

correct,

for

faith in

the

particular

candidate

chosen.

Something

must make

at

least a few scientists

feel that the new

proposal

is on

the

right

track

...

(Kuhn

[1972],

p. 158).

For

Kuhn,

belief or faith

in a

theory's

promise

is a most

important

factor

relevant

to

theory-choice,

but

the faith need

not be based on a rational

inference

(and

thus

would be

rejected by

the standard

conception

of

rationality

as

irrational),

but based

on a rational

judgement

or an

insight:

the

scientists

feel that

the new

proposal

is

on the

right

track.

Only specialists

can

make

such a

judgement.

Even

if the

judgement

is sometimes

inarticulate

or

turns out to be

wrong,

might

we

say

that

it

is

irrational?

I think not. The

liberalisation

of

rationality

must

be extended

to

the

point

of

including

such a

judgement among the rational ones.

Wuhan

University

People's

Republic

of

China

REFERENCES

HEMPEL,

C.

G.

[1965]:

Aspects

of

Scientific

Explanation

and

Other

Essays

in

the

Philosophy

of

Science.

HEMPEL,

C. G.

[1981]:

'Turns

in the Evolution of Problem

of

Induction',

Synthese, 46,

p.

402.

KUHN,

T.

[I970o]:

Reflections

on

My

Critics',

in I. Lakatos

and

A.

Musgrave

(eds.),

Criticism

and the Growthof Knowledge.

KUHN,

T.

[1972]:

The Structure

of

Scientific

Revolutions,

2nd ed.

LAKATOS,

I. and

MUSGRAVE,

A.

(eds.)

[I970o]:

Criticism

and the

Growth

of

Knowledge.

MCMULLIN,

E.

[1976]:

'The

Fertility

of

Theory

and

the Unit

of

Appraisal

in

Science',

in R.

S.

Cohen et

al.

(eds.),

Essay

in

Memory of

Imre

Lakatos.

POPPER,

K.

[1972]:

Objective

Knowledge.

PUTNAM,

H.

[198

1]:

'The

Impact

of Science

on

Modern

Conceptions

of

Rationality',

Synthese,

46, p.

375.


16/16


Formal or

Informal?

423

SCHEFFLER,

I.

[1976]:

Science

and

Subjectivity.

SHAPERE,

D.

[1974]:

'Discovery, Rationality

and

Progress

in

Science:

A

Perspective

in the

Philosophy

of

Science',

in

K.

Schaffer and

R.

Cohen

(eds.),

PSA

1972.

WARTOFSKY,

ARX

W. [I980]: 'Scientific Judgement: Creativity and Discovery in Scientific

Thought',

in

T. Nickles

(ed.),

Scientific

Discovery:

Case Studies.

ZAHAR,

E.

[1982]:

'Feyerabend

on

Observation and

Empirical

Content',

British

Journalfor

the

Philosophy

of

Science,

33,

P. 407.

scientific rationality, formal or informal

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