Updated:    03 March 2000

 

The Realist Picture

 

 

       Start with observations

 

       Seek explanations

 

       Produce theories

 

       Explain by reference to the unobserved

 

 

       Inference to the best explanation

                   Galileo - mountains on the moon

                   Einstein - atoms via Brownian motion

                   Thomson - electrons via scintillations

 

 

       Confirm by successful novel predictions

1.

 


 

The theory provides a literally true (or truth-like) account of the underlying mechanisms in the world

 

 

Real realism –

 

truth as correspondence

or

reject reconstruals of truth (eg Peirce)

                  

 

Explanatory Realism

 

Verisimilitude

 

Aim of science is the truth-related aim of having theories of ever greater verisimilitude.

 

 

Problems:               meaning of approximate truth

                                                       evidence for it

2.

 

 

 

Observational success of science

 

 

Science uses IBE

 

 

Use IBE in your theory of science

 

 

What is it about today’s theories that enables them to give better predictions?

 

 

theories are more approximately true

 

 

advanced in contexts of Kuhnian scepticism

3.


 

 

Instrumentalism

 

 

Historical sources

 

 

Limited epistemic skepticism

 

How do you know about electrons ?

 

 

Experience is the source of all knowledge, don’t have experience of electrons.

 

 

Limited - knowledge of observable states

4.

 


 

Limited semantic skepticism

 

 

What do you mean?

 

 

 

Cannot give verbal definitions or ostensive examples for theoretical terms.

 

 

No more meaning than Hodge’s uninterpreted symbols

5.


 

Instrumentalism

 

 

       theories are just predictive tools

 

 

1. Semantic

 

       T-terms lack meaning

 

       T-sentences lack truth-values

 

 

2. Epistemological

 

T-terms have meaning and T sentences have truth-values.  But utterly unknowable.

6.


 

 

Constructive Empiricism

 

 

van Fraassen: The Scientific Image

 

 

aim of science: empirical adequacy

 

 

scientist does not believe a theory

 

 

scientist “accepts” a theory

 

 

       = believing in its predictive success

7.


 

 

Objections to Explanatory Realism

 

 

Nothing to explain.

 

 

Theories picked for predictive power. That is why they are predictively successful.

 

 

IBE

 

- question begging - instrumentalist challenges its use as an epistemic tool in science

 

- explanation not linked to truth

8.


 

 

no satisfactory account of verisimilitude (Laudan : Science and Values)

 

 

 

historical record is dubious (Laudan)

 

 

 

Underdetermination of theory by data.

9.


Constructive Empiricism

 

1.    semantic realism

 

2.         Not traditional scepticism

 

       IBE ok from observables to observables

 

Crucial to distinquish between:

       O and T

       O and non-O

 

       i) Schlick : O

                   absolute certainty

                   inner experience - sense data

 

       ii) Carnap - matter of degree

                   quickly, accurately, confidently decide

 

       iii) van Fraassen - biological basis - what humans could (if suitably located) settle by using unaided senses

10.


 

 

 

Local realism        

 

 

aim of science goes beyond that of empirical adequacy

 

 

Inference to the Best Explanation

 

global use

      

 

Argues for TV on the grounds that it provides best explanation of increasing observational successes of science

 

local uses

                  

Seeks to justify positing atoms, electrons etc

 

Miller “book length argument for realism”

11.


 

      

Underdetermination of theory by data

 

       Copernicus

       Ptolemy

 

 

see hand-out

 

Underdetermination by the actual available data

 

 

Threat to IBE ?

 

 

Agnostic realism

       - wait and see

12.


 

 

Undetermination of theory by all actual and possible data

 

 

For any theory T1 there is a theory T2 :

 

 

T1 and T2 are incompatible.

 

 

T1 and T2 are empirically equivalent

 

T1 and T2 are fare equally well on all other epistemic principles of theory choice.

13.

 


 

Strong UTD - applies to all theories

 

 

Weak - applies to some theories

 

 

Observationally omniscient God

 

 

What hope for realism?

 

 

Inter-Galactic Conference

 

Newton ...  Einstein

 

Notwen...   Nietsnie

14.