Veni, Vidi, Induxi

Louis, Jessica, Sandra, Floris

UC 2002 Fall

Sci101 History & Philosophy of Science

Ladyman Chapter 1-2

Order of Appearance

i. Sandra (Background Information)ii. Jessica & Louis (Discussion)iii. Floris (Gruesome Theories)iv. Louis & Jessica (Discussion)

Background Information

Sandra

Scientific revolution• Aristotle

– deduction

• Bacon– induction

Deduction

All M are P

S is M

S is P

Induction

M1, M2, M3, Mn are P

All M are P

Hume

• Addressed problems of induction

• Cause and effect

Discussion

Jessica & Louis

Hume says:

In each case, the moral is that a priori reasoning and argument

gets us nowhere: "it is only experience which teaches us the nature and bounds of cause and

effect, and enables us to infer the existence of one object from that

of another.”

Gruesome Theories

Floris

The role of theories in inductive science.

Topic Outline

I. What are scientific theories?– Characteristics, Inner Mechanics

II. What can go wrong?– The role of theories in inductive

reasoning.– The ‘Grue’-paradox

Brainstorm

• Once again; brainstorm about

‘Theory’

“I (Ptolemy) designed my theory about the solar system to explain the observed movement of the planets and stars.”

Theory Characteristics I• A theory tries to explain

why certain events take place.

• Example:

Theory Characteristics II

• How do they go about explaining?• Compare:

– ‘This here is a chair.’ (hardly a theory)

– ‘There is a force on this chair.’• Can we directly see a force?

– Only its results.

• Scientific Theories postulate things that cannot be directly perceived.

Likewise,• Likewise, a generalised

rule cannot be perceived.• Causal relation:

– ‘If I drop this chair out of the window, it will fall to the ground.’

– We cannot directly ‘see’ this rule in nature; it rather is a pronunciation of our notion of regularity in accumulated perceptions of objects falling when dropped.

Results• Since we cannot directly perceive what

a theory postulates, therefore, in order to verify the theory, we can only look at the perceivable predictions it makes.

Theory (nice story)

Unperceivable Concepts

Generalised Rules

TheoreticalObservations

X1

X2

X3

X4

Xa

Xb

explain

predictXc

Xd

test X5

induction

deduction

ExampleThis thing falls, that thing falls to the ground.

Everything that is released falls to the ground.

Things fall because there is a gravitational force being applied to it (depending on size of attracting body).

In that case, things on the moon will fall at a different speed.

This thing falls at a different speed.Observatio

n

Generalised Rule

Theory

Problem about Scientific Theories

• But if the predictions are correct, then the theory does not have to be right (consider the fairy tale).

• Therefore, there are two kinds of problems:

I. We cannot verify all possible cases a theory covers. (Presented by Ladyman) (philosophy of science)

II. We cannot verify the theory in itself. (metaphysics)

Illustration Problem

• Being ‘grue’ means being green before 2005 and blue after 2005.

• Now we have a theory that says that all emeralds are ‘grue.’

• Every emerald we see seems to add up to the conclusion that this theory is correct.

Ockham’s Razor• William of

Ockham’s Razor:

‘If all things are equal, the most simple explanation is the right one.’

• By the way, he was a Medieval Philosopher.

Conclusions• Scientific theories are designed

to explain.• Scientific theories tend to

postulate concepts that cannot be directly perceived.

• Problems about induction:I. We cannot verify all possible

cases a theory covers. (presented by Ladyman)

II. We cannot verify the theory in itself.

Discussion

Louis & Jessica

Science is the religion of modern societies

Science is the religion of modern societies

Definition of religion (the concise Oxford dictionary):

• The belief in a superhuman controlling power, esp. in a personal God or gods entitled to obedience and worship

• A particular system of faith and worship• A thing that one is devoted to• Et cetera

Science is the religion of modern societies

Since scientific theory in itself cannot be observed, therefore it could be just a likely explanation. It takes a leap of faith to believe

that the theory is actually true.

The End• Have a nice break.

• A copy of this presentation is available for downloading at http://vanvugt.cjb.net