The Problem of Induction in Science

The Problem of Induction

Inductive reasoning goes from the particular to the general, from the observed to the unobserved.

Practical Problems

• How many observations are enough?
• Even well-confirmed hypotheses can later turn out to be wrong.
• Most scientists believe they really are discovering the fundamental laws of the universe, yet we have observed only a minute fraction of the universe.

Theoretical Problem

Science is supposed to be an empirical discipline that makes no claims beyond what is observed. However, this would stop any hypothesis from going from the particular to the general.

Key Thinkers and Scientific Method

Karl Popper (1902-94)

Rejected theories that tried to explain everything.

Alfred Adler (1870-1937)

Believed that human beings are dominated by feelings of inferiority.

Isaac Newton (1643-1727)

Predicted that attractive forces would collapse the universe.

Dmitri Mendeleyev (1834-1907)

Came up with the periodic table by arranging elements according to their atomic weights.

Charles Darwin (1809-82)

Theory of evolution required the Earth to be hundreds of millions of years old to allow enough time for species to evolve.

Lord Kelvin (1824-1907)

The leading physicist of the day, calculated that the Earth was no more than 100 million years old.

Popper's Conjectures

Popper concluded that it is impossible to test all possible cases to prove a hypothesis.

• Scientists should try to disprove a given hypothesis.
• If it cannot be proved to be false, it should be provisionally accepted.
• It can never be absolutely accepted unless all possible situations are tested.
• A better theory may be presented in the future.

Auxiliary Hypotheses

Theories should not be immediately rejected when falsified, as counter-evidence may be incorrect.

Examples of Theory Change

• Uranus did not behave as predicted by Newton's laws. So, Neptune was predicted and was later found.
• Mercury's behaviour could not be explained by Newton's laws. So, Vulcan was predicted, but did not exist. This led to a Scientific Revolution, and Newtonian laws were replaced by the theory of Relativity.

Philosophical Views

Empiricist

Tend to reject the theory: experience is the main source of knowledge.

Rationalist

Tend to stick with a beautiful theory: reason is the main source of knowledge.