The Meaning of Meaning

Imagining visiting another planet with another lifeform on it but without knowing that it differs from what we already know is what Hilary Putnam, an American philosopher whose mind was not only full of philosophical but also of scientific questions, is introducing in his text ’The Meaning of Meaning’ as ’Twin Earth’.

Falling from the dark and gloomy clouds above of us, rain started to drop on our faces. We assume it is rain but in fact it is not. It has the same appearance, smell and feeling of rain that we know fom our earth but if we take a closer look we will notice that the rain from Twin Earth does not share the same chemical structure as the water we are familiar with. This raises the question of if what we perceive as the same is truly the same.
What we are dealing with is called intension and extension. Intension refers to a concept or meaning that one has in mind and extension refers to something that exists. Applied to Twin Earth, the intension “water“ is used as a substantive of the chemical formula “H₂O“ whereas its extension could be “rain“ or other known forms of this formula such as snow. Although the water on earth and Twin earth might have the same intension by a person from earth, the extension would differ since rain or snow do not exist because they contain of H₂O and not ’XYZ’, the chemical structure for Twin Earth’s water.