Unit 1What can we know?

What is science?

•Write down what you think science is•Name five examples

• Science comes from the Latin word scientia which means knowledge. – Science gives us knowledge of reality. – This knowledge is objective, generalisable, controllable

The traditional view of science

• Philosophy comes from the Greek φιλοσοφία (philosophia) which means love of wisdom.

• Philosophy studies general and fundamental problems.

• The philosophy of science can help us reflect on the nature of science.

Ont

olog

y

What is reality?

Epist

emol

ogy

What can we know about reality?

Met

hodo

logy How do

we get to know this? So

ciol

ogy

of s

cien

ce How does science actually work?

The definition of science effects real life

Rationalism and Empiricism

•Deduction•A prioriRationalism

• Induction•A posterioriEmpiricism

• Deductive reasoning goes from all (a general rule) to one (a specific case).

• Inductive reasoning goes from one (a bunch of single data) to all (a general conclusion).

• A priori= before experience• A posteriori = after experience

Rationalism and deduction

Descartes (1596-1650): Doubt your senses

What if there is no God, but just an evil demon tricking us

Then I might be sleeping, dreaming I am awake

Cogito ergo sum?

But the demon can never trick me into the idea I don’t exist.

Deduction

• Deduction is logical reasoning. • Deductive knowledge is a priori knowledge

that is known independent of experience. • Deductive arguments are purely logical.

a deductive inference

Standard example of a deductive inference:Premises All men are

mortal.Socrates is a man.

Conclusion Socrates is mortal.

Empiricism and induction

Induction

• Inductive knowledge is knowledge based on sensory experience.

• Inductive knowledge is a posteriori knowledge, knowledge that is gained by experience (that is, it is empirical, or arrived at afterward).

David Hume’s (1711-1776) fork

• Analytic: statements about ideas• Synthetic: statements about the world

• Example of an analytical sentence:All bachelors are unmarried.• Example of a synthetic sentence:All bachelors are bald.

Hume’s problem was that it is almost impossible to go from synthetic to analytic statements.

• Because we can never relate the analytic sentences to the real world it is meaningless, they only speaks about them self.

• Consider the example of the bachelor: it is a tautological sentence, it is always valid regardless of your data.

A thousand white swans

• Take the example of a white swan. Can we be certain that if we see a thousand white swans, that all swans are white?

• No. – Even if we have a thousand observations like: this

swan is white, we can never relate this to the rule all swans are white.

– Only if we would see every swan in the universe – now and in the future- which is impossible.

The fact that the sun has risen everyday up until now may not prove that it will rise tomorrow,

but surely it gives us a very good reason to think it will?