What’s In That Glass?
The linguists and scientists among you will hopefully find this of interest and/or amusement.
One recurring topic in philosophy of language and philosophy of mind, especially the analytic branches of those fields, is the question of what determines the meaning of the words a speaker uses. It should be a pretty uncontroversial assumption that a speaker can’t make words mean just anything. Otherwise we wouldn’t get to have fun correcting people on their use of ‘it’s’ and ‘its,’ ‘affect’ and ‘effect,’ and so on. So what’s the piece of linguistic magic that connects a particular utterance to a particular set of things or phenomena? Harvard philosopher Hilary Putnam argued in the 1970s that what the speaker intends or thinks the word means has no bearing on the actual meaning, and came up with a thought experiment designed to prove his case. It goes something like this:
Imagine a world somewhere that is exactly identical to Earth, right down to the population and languages spoken; call it Twin Earth. The only difference is that the colorless, tasteless liquid that fills rivers and oceans, boils at 212 degrees Fahrenheit, freezes at 32 degrees, makes up the majority of the human body, and is called ‘water’ by the Twin Earth equivalent of English-speakers, does not have a chemical composition of two atoms of hydrogen plus one of oxygen. Instead it has some bizarrely complex structure that we will abbreviate as XYZ. There is a substance with a chemical composition of two atoms of hydrogen plus one of oxygen on Twin Earth, but it’s an incredibly rare substance that has a black color and a tar-like consistency.
Now imagine that you somehow manage to take a trip to Twin Earth, and you’re pretty thirsty from the long journey. You ask your host for a glass of water. What are you really asking for? According to Putnam, you’re asking for the tarry stuff. You come from the community of Earth-English speakers, and the words you say still mean what they would on Earth, not what they would on Twin Earth.
OK, you may say, fair enough, but how does that make me ask for the tarry stuff instead of the clear stuff? Especially since my hosts will give me a glass of the clear stuff and think nothing of it? According to Putnam, what ‘water’ really means is not ‘the colorless, tasteless liquid that fills rivers and oceans, boils at 212 degrees Fahrenheit, freezes at 32 degrees, makes up the majority of the human body, and so on.’ ‘Water’ means ‘the substance with a chemical composition of two atoms of hydrogen plus one of oxygen,’ and that’s all there is to it. The former definition is a colloquial, secondhand kind of thing, one that’s vague and somewhat problematic at the edges. Add salt and food coloring to a glass of water, and it’s not colorless and tasteless anymore – is it still water? What about heavy water? Mineral water? We need something more precise.
What’s the essence of water, then, the thing that makes it what it is? According to our current scientific understanding, that would be its chemical structure. Relatively few of us have extensively studied the chemical composition of the stuff that comes out of our tap, so we defer to the experts who have, and when they tell us that water is made up of two atoms of hydrogen for every atom of oxygen, we defer to their knowledge and let it determine the extension of the word. (The extension of a word is the set of all the things and phenomena in the world that can be correctly referred to by that word.) Now, even before we knew the chemical composition of water, it had that chemical composition – its essence was always fixed, and so according to Putnam the meaning of the word ‘water’ was always fixed, and it was the job of our experts to determine what that essence was, not decide it for themselves.
The net result is that if our experts were to analyze the glass of liquid your Twin Earth hosts gave to you, they would discover that it was XYZ and not H2O, and they would tell you that, in fact, it wasn’t water. You were speaking a different language from your hosts, and it was a happy accident that the resulting error in translation resulted in you getting the kind of beverage you wanted. The funny thing is, since there are not in fact any experts analyzing the glass, both you and your hosts are unaware that you were really asking for the tarry stuff. Whatever was going on in your head – images of a glass of clear liquid, swimming pools, whatever – had absolutely nothing to do with the actual meaning of what you actually said. What mattered was the external conditions – the structure of the natural world, and the judgment of the experts who analyze that world. Putnam’s position, therefore, came to be known as externalism, and folks are still arguing about it today, even as it’s been refined and expanded through subsequent thought experiments. It all starts on Twin Earth with that glass of liquid, though, so that’s where I figured we’d kick off the conversation.
So what do you think?
About Dave Thomer
Born and raised in Philadelphia. Studied philosophy at Fordham University in the Bronx, where I made many great friends and met my wonderful wife. We moved back to Philadelphia, where I studied philosophy some more and became a teacher. Online and off, I'm looking for ways that we can be better citizens and build stronger communities.