1. How the Growth of Success stopped Theory Change
4/16/ Oct-05
How the Growth of Success stopped Theory Change
Ludwig Fahrbach
Universität Düsseldorf

2. Overview Realist: Anti-realist: My reply:
4/16/ Oct-05
Overview
Realist:
“Successful theories are true.”
Anti-realist:
“The history of science is full of counterexamples, i.e., successful, but false theories.”
My reply:
All of these counterexamples enjoyed only comparatively low degrees of success.
Our current best theories enjoy much higher degrees of success.

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1. The Realism Debate

4. The success-to-truth principle*
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The success-to-truth principle*
If a scientific theory is empirically successful, then it is approximately true.
A theory is empirically successful, iff
the predictions deduced from the theory by scientists fit with the observations gathered by scientists, and
there are no serious cases of non-fit.
In what follows:
“true” short for “approximately true”
“successful” short for “empirically successful”
best theories at some point in time = most successful theories at that time

5. The positions* The realist endorses the success-to-truth principle
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The positions*
The realist
endorses the success-to-truth principle
therefore accepts our current best (i.e. most successful) theories as true (e.g., theory of evolution, germ theory of disease, etc.)
The anti-realist
rejects the success-to-truth principle
is agnostic about or rejects (important parts of) our current best theories

6. The arguments The realist supports the success-to-truth principle with
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The arguments
The realist supports the success-to-truth principle with
the no-miracles argument
The anti-realist attacks the success-to-truth principle with
the argument from the underdetermination of theories by all possible evidence
the pessimistic meta-induction (PI, for short)

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The PI*
The past of science is full of once successful scientific theories that were accepted for some time, but later shown to be false.
These theories constitute counterexamples to the success-to-truth principle; they undermine it.

8. Laudan’s list of successful, but refuted theories
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Laudan’s list of successful, but refuted theories
the crystalline spheres of ancient and medieval astronomy
the humoral theory of medicine
the effluvial theory of static electricity
the ‘catastrophist’ geology (including Noah’s deluge)
the phlogiston theory of chemistry
the caloric theory of heat
the vibratory theory of heat
the vital force theories of physiology
the electromagnetic ether
the optical ether
the theory of circular inertia
theories of spontaneous generation

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2. Degrees of success

11. Grading the notion of success*
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Grading the notion of success*
Scientific theories vary with respect to their degree of success.
The degree of success of a theory increases, iff the passed tests increase in number and quality. In general, this is the case
if scientists are able to derive more predictions from the theory
if the derived predictions become more precise
if the derived predictions of the theory gain in variety
if scientists gather more data
if the gathered data are more precise
if the gathered data gain in variety

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success
scientific fields

13. 4/16/ Oct-05
success
scientific fields

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Main thesis*
Among theories with very high degrees of success (e.g., our current most successful theories) almost no refutations have occurred.
Practically all successful refuted theories enjoyed rather low degrees of success.

15. * Examples of theories with very high degrees of success:
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Examples of theories with very high degrees of success:
the periodic system of elements
the theory of evolution
“Fixed stars are like our sun.”
“All organisms consist of cells.“
the conservation of energy + mass
“Water is H2O.“
“The brain is a net of neurons.“
And so on

16. * current best theories refuted theories scientific disciplines
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success
realm of stability
current best theories
refuted theories
scientific disciplines

17. 4/16/ Oct-05
How realism is saved*
Refined success-to-truth principle: “If a theory enjoys a high degree of success, it is true.”
The refined success-to-truth principle is not undermined by counterexamples.
Refined realism: “The refined success-to-truth principle is correct.”
Refined realism is saved from the PI.

18. 4/16/ Oct-05
The big boost*
Consider how the degrees of success of the best theories has increased over the history of science.
The big boost: By far most of that growth occurred in the recent past, i.e., in the last few decades.
(More generally, during the history of science the degree of success of the best theories has very roughly grown exponentially.)

19. 3. Five Indicators of Success
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3. Five Indicators of Success

20. First indicator: the exponential growth of scientific work*
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First indicator: the exponential growth of scientific work*
Since 1700, the number of scientific publications has doubled every years.
The same holds for the number of scientists. -∞
1960
1980
2000

21. The other four indicators
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The other four indicators
In general, the success of theories increases, when
the computing power increases,
the amount of data increases,
the data have more variety,
the data have a higher degree of precision.

22. Second indicator: computing power*
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Second indicator: computing power*
Benefits of computing power:
Computing power is needed to derive observable predictions from the theory, e.g. to solve equations numerically. Predictions can then become more numerous, more varied and more precise.
Automated gathering of data
Storing of data
Searching in data
Simulations
Etc.

23. Growth of computing power
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Growth of computing power
growth of manpower
better mathematical and computational methods
better instruments (abacus, logarithmic tables, etc.)
in the last 50 years power of computers doubling every 2 years

24. More on the benefits of computing power
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More on the benefits of computing power
„It is now possible to assign a homework problem in computational fluid dynamics, the solution of which would have represented a major breakthrough or could have formed the basis of a Ph.D. dissertation in the 1950s or 1960s.” (Tannehill et al. 1997, p. 5, quoted by Paul Humphreys 2004, Extending Ourselves, p. 49)

25. Third indicator: amount of data*
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Third indicator: amount of data*
The amount of data in many scientific fields grew at least proportionally to manpower.
In the last few decades, the gathering of data has become more and more automated.

26. Fourth indicator: diversity of data*
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Fourth indicator: diversity of data*
100 years ago:
light microscope
Today:
many types of light microscopes (polarization, fluorescence, phase contrast, ect.)
many types of electron microscopes
some types of scanning probe microscopes
some types of acoustic microscopes
Etc.

27. Fifth indicator: precision of data*
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Fifth indicator: precision of data*
In many scientific fields, every new generation of instruments has led to an (often dramatic) improvement of the precision of data.
Example: In the 1980s GPS increased the precision of distance measurements in geology 100fold.

28. Unification and Success
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Unification and Success

29. Did the increase in success happen
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How precisely has the growth of the five indicators led to a big boost in success for our best theories?
Did the increase in success happen
in a considerable number of big steps (e.g. by novel predictions)?
in a high number of medium-sized steps?
in a very high number of small steps?
all of the above?
Answer (work in progress):
depends on the scientific field and theory
typically all of the above, i.e., a lot of overkill [

30. 4/16/ Oct-05
Core theories
Many of our current best theories have strong unifying power.
This means that a lot of work in their respective fields are applications of them.
Call such a theory a “core theory in its field”. -

31. The accumulation of small and intermediate successes
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The accumulation of small and intermediate successes
Due to the growth of scientific work, computing power, amount of data, etc., the number of such applications of the core theories has increased enormously.
In many such applications the core theory enjoyed small or moderate successes.
These small or moderate successes accumulate to a very high overall amount of increase in success.
Examples: The periodic system of elements enjoyed small or moderate successes in millions of applications.

32. How the Big Boost Supports the Main Thesis
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How the Big Boost Supports
the Main Thesis

33. big boost current best theories refuted theories scientific fields
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success
realm of stability
current best theories
big boost
1920
refuted theories
scientific fields

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The refuted theories*
Practically all examples of successful, but refuted theories presented in the philosophical literature are older than 80 years.
If in the last 80 years there had been some refuted theories among the best theories, then they would have been sufficiently salient for philosophers to present them. -

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Theories of light
1900
1800
2000
1700

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Theories of light
1900
1800
2000
1700
1980 -

37. Objections Early theories with very high success
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Objections
Early theories with very high success
Refutations of theories in the last few decades

38. Conclusion* In the last few decades there was a big boost of success.
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Conclusion*
In the last few decades there was a big boost of success.
The best theories of the recent past received that boost, while none of them was refuted.
No refuted theory received the big boost.
Hence, the inference from very high success to truth has no counterexamples.

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THE END